December 2015 Japan International Cooperation Agency Kokusai Kogyo Co., Ltd. THE PROJECT FOR GROUNDWATER RESOURCES ASSESSMENT IN THE MIDDLE AWASH RIVER BASIN IN THE FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA FINAL REPORT SUPPORTING REPORT The Federal Democratic Republic of Ethiopia Ministry of Water, Irrigation and Electricity
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December 2015
Japan International Cooperation Agency
Kokusai Kogyo Co., Ltd.
THE PROJECT FOR GROUNDWATER RESOURCES ASSESSMENT IN THE
MIDDLE AWASH RIVER BASIN IN THE FEDERAL DEMOCRATIC REPUBLIC OF
ETHIOPIA
FINAL REPORTSUPPORTING REPORT
The Federal Democratic Republic of EthiopiaMinistry of Water, Irrigation and Electricity
Composition of the Report
Executive Summary
Main Report
Supporting Report
Data Book
Geological and Hydrogeological Maps
This Report is prepared based on the price level and exchange rate of July 2015. The exchange rate is:
US$1.0 = ETB20.6298 = JPY123.80
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Lake Ziway
Lake Koka
Lake Yardi
Lake Ertele
Lake Abijata
Lake DendiLake Ala Semite
Lake Wenchi
Lake Dalay
Lake Goletsho
Awash Wenz
Abay
Ramis
J ema
Bilate Wabe Shebele Wenz
Wechti Wenz
MugerW
enz
Addis Abeba
Nazret
Yilu
Gola
Lemi
Mine
Guna
Meki
Dera
Kula
Rago
Bube
Robi
Hobe
Bu-i
Teji
Ambo
Doba
Erer
GotaBike
Hirna
Wanje
Akaki
Chole
Iteya
Arara
Suten
Ada-a
Kibet
Deder
Asela
Ramis
Ziway
Magna
ModjoHmero
Harew
Sheno
Fiche
Robit
Sagure
Diksis
Arerti
Agemti
Molale
Sodoma
Merewa
Woliso
Huruta
Hujufa
Tibila
Koshim
Ombole
Dilila
Bedesa
Godina
Ginchi
Asebot
Mesala
Chacha
Gewane
Dalocha
Chancho
Fulensa
Gelemso
Melkasa
Endibir
Roepeyh
Enewari
Meranga
Rukeyisa
Butajira
Gunchire
Dida Adi
Metehara
Aro Dimtu
Adis Amba
Tulu Bolo
Muke Ture
Haro Kile
Adis Alem
Harawacha
Tarma Ber
Welenchiti
Mucha Roba
Melka Jilo
Debre Sina
Goha Tsion
Debre Tsige
Arba Reketi
Midre Kebda
Bantu Liben
Addis Hiwot
Chefe Donsa
Debre Zeyit
Alem Ketema
Gojo (Jeldu)
Guba Koricha
Asebe Teferi
Shola Gebeya
Debre Birhan
Teferi Birhan
Anchar Bedeyi
Gebre Guracha
Ejere N Shewa
Sire W Hararghe
Arb Gebeya W Shewa
Abomsa (Tinsae Birhan)
Loko
Bofa
Arba
Muger
Eurdo
Koshe
Fetra
Duber
Beltu
Jihur
Sembo
Afdem
Dejen
Ejersa
Boreda
Segele
Kutara
Gebiba
Deneba
Fitale
Mezezo
Jebuha
Adulala
Ankober
Kechemo
Sululta
Ginager
Chifara
Mechara
Berehet
KurkuraDinkiti
Kachisi
Mendida
Tedo Ber
Delajebo
Jima Arsi
Alem Tena
Yemistina
Adami Tulu
Mama Midir
Sirtu Ager
Alem Gebeya
Melka Werer
Biyo Karaba
Tikur Chika
Hagere Sernay
Sheik Hussein
Melka Kunture
41°0'0"E
41°0'0"E
40°0'0"E
40°0'0"E
39°0'0"E
39°0'0"E
38°0'0"E
38°0'0"E
10°0
'0"N
10°0
'0"N
9°0'
0"N
9°0'
0"N
8°0'
0"N
8°0'
0"N
400000
400000
500000
500000
600000
600000
700000
700000
9000
00
9000
00
1000
000
1000
000
1100
000
1100
000
LegendStudy Area
Towns
\ Capital
!5 Regional Capital
!!! Major towns
!! Other towns
Major Rivers
Roads
Trunk
Link
Main Access
Feeder
Collector
New Proposed
Unclassified
0 5025km
´
LOCATION MAP
AbbayAwash
Wabi Shebele Aysha
Genale-Dawa
Tekeze
Omo-Gibe
Denakle
Baro-Akobo
Rift Valley
Mereb
Aysha
OROMIA
SOMALI REGION
AMHARA
AFAR
TIGRAY
SOUTHERN REGIO
50°0'0"E
45°0'0"E
45°0'0"E
40°0'0"E
40°0'0"E
35°0'0"E
35°0'0"E
15°0
'0"N
10°0
'0"N
10°0
'0"N
5°0'
0"N
5°0'
0"N
LegendStudy Area
Region
Major Basin 0 200 400100km
´
Addis Ababa
Project Area
Federal Democratic Republic of Ethiopia
Project Area
i
CONTENTS Location Map Contents List of Tables List of Figures Abbreviations Project Photo
Page:
1 Meteorology and Hydrology ................................................ 1-1
1.1 Review of meteorology data ............................................................................ 1-1 1.1.1 Meteorological observation network and items ................................ 1-1 1.1.2 Rainfall .............................................................................................. 1-2 1.1.3 Evaporation........................................................................................ 1-7 1.1.4 Temperature and other data ............................................................. 1-10
1.2 Review of hydrology data .............................................................................. 1-13 1.2.1 Hydrological stations in the middle Awash River Basin ................. 1-13 1.2.2 River flow ........................................................................................ 1-15
1.3 Hydrological analysis .................................................................................... 1-16 1.3.1 Introduction ..................................................................................... 1-16 1.3.2 River flow analysis .......................................................................... 1-19 1.3.3 Water balance analysis .................................................................... 1-24 1.3.4 Results of water balance analysis .................................................... 1-27
2 Geology ............................................................................... 2-1
2.1 Adama town, Mt. Boseti and its surrounding areas ......................................... 2-1 2.1.1 General .............................................................................................. 2-1 2.1.2 Geological unit .................................................................................. 2-4
2.2 Kone – Mt. Fentale and its surrounding areas ............................................... 2-24 2.2.1 General ............................................................................................ 2-24 2.2.2 Geological unit ................................................................................ 2-26
2.3 Mojo town – Arerti town – Debre Birhan town and its surrounding areas ............................................................................................................... 2-44 2.3.1 General ............................................................................................ 2-44 2.3.2 Geological unit ................................................................................ 2-46
2.4 Awash town – Asebe Teferi town and its surrounding areas ........................ 2-61 2.4.1 General ............................................................................................ 2-61 2.4.2 Geological unit ................................................................................ 2-62
2.5 Correlation of stratigraphy of each part of the study area ............................. 2-81
2.6 Correlation of stratigraphy with previous studies .......................................... 2-83
2.7 Geological structure ....................................................................................... 2-85 2.7.1 Fault system ..................................................................................... 2-85 2.7.2 Active structures .............................................................................. 2-85
2.8 Volcanic activity ............................................................................................ 2-86
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2.8.1 Characteristics of volcanic topography in the middle Awash River basin ....................................................................................... 2-86
2.8.2 Volcanic history in the middle Awash River Basin ........................ 2-89
3 Hydrogeology ...................................................................... 3-1
3.1 Topography ...................................................................................................... 3-1 3.1.1 General .............................................................................................. 3-1 3.1.2 Hydrographic system ......................................................................... 3-2
3.2 Satellite image analysis ................................................................................... 3-4 3.2.1 Satellite image ................................................................................... 3-4
3.3 Previous studies of hydrogeology .................................................................. 3-12
3.4 Groundwater potential ................................................................................... 3-29 3.4.2 Classification and characteristic of aquifers .................................... 3-33 3.4.3 Evaluation of aquifer potential ........................................................ 3-36
3.5 Water quality testing ...................................................................................... 3-37 3.5.1 Results of water quality testing ....................................................... 3-37 3.5.2 Analysis items and methodology..................................................... 3-43 3.5.3 Results of water quality testing ....................................................... 3-44
4 Geophysical Survey ............................................................ 4-1
4.1 Study area and objective of geophysical survey .............................................. 4-1 4.1.1 Study area .......................................................................................... 4-1 4.1.2 Objective of geophysical survey ....................................................... 4-1
4.2 Survey points ................................................................................................... 4-1 4.2.1 Number of survey .............................................................................. 4-1 4.2.2 Reconnaissance and selection of prospecting sites ........................... 4-2
4.3 Survey method ............................................................................................... 4-11 4.3.1 Vertical electric sounding (VES) ..................................................... 4-11 4.3.2 TEM electro-magnetic sounding (TEM) ......................................... 4-16
4.4 Survey analysis .............................................................................................. 4-20 4.4.1 Results of geophysical investigation ............................................... 4-20 4.4.2 Results of geophysical inversion analysis ....................................... 4-21 4.4.3 Comparison among VES, TEM and geology in the middle
Awash River Basin .......................................................................... 4-29 4.4.4 Hydrogeological interpretation by the results of geophysical
survey .............................................................................................. 4-31
5 Observation Well Drilling and Pumping Test ....................... 5-1
5.1 Purpose and methodology of well drilling ...................................................... 5-1 5.1.1 Purpose .............................................................................................. 5-1 5.1.2 Methodology...................................................................................... 5-1
5.2 Selection of drilling sites ................................................................................. 5-3 5.2.1 Summary of drilling work ................................................................. 5-5 5.2.2 Lithological conditions (Drilling result of observation
wells) ................................................................................................. 5-5 5.2.3 Results of geophysical logging ........................................................ 5-11
iii
5.2.4 Correlation of results between drilling and geophysical survey .............................................................................................. 5-17
5.3 Pumping test .................................................................................................. 5-34 5.3.1 Introduction ..................................................................................... 5-34 5.3.2 Step-drawdown test ......................................................................... 5-35 5.3.3 Continuous test ................................................................................ 5-43 5.3.4 Recovery test ................................................................................... 5-59 5.3.5 Conclusions of the pumping tests .................................................... 5-64
5.4 Hydrogeological aspects and prospects ......................................................... 5-66 5.4.1 Subsurface geology and physical logging at each site .................... 5-66 5.4.2 Summary of aquifer at each site ...................................................... 5-70
5.5 Results of water level monitoring .................................................................. 5-73 5.5.1 Outline ............................................................................................. 5-73 5.5.2 Water level monitoring results ........................................................ 5-74
6 GIS/DB for Groundwater Resources Assessment .............. 6-1
6.1 General ............................................................................................................. 6-1
6.2 Existing Groundwater Information System in Ethiopia .................................. 6-1 6.2.1 Current status of Ethiopia National Ground Water
Information System (ENGWIS) ........................................................ 6-1 6.2.2 Current status of a GIS/DB prepared in the previous JICA
project ................................................................................................ 6-2
6.3 Data collection and compilation ...................................................................... 6-3 6.3.1 Basic data........................................................................................... 6-3 6.3.2 Natural condition ............................................................................... 6-4 6.3.3 Social condition ................................................................................. 6-5 6.3.4 Groundwater information .................................................................. 6-6
6.4 Land use map ................................................................................................... 6-8
6.5 Outline of GIS/Database for the groundwater resource assessment ................ 6-9 6.6 System requirements/configurations ............................................................. 6-10
6.7 Interface of the GIS/DB ................................................................................. 6-11
6.8 Examples of utilization of GIS/Database ...................................................... 6-14
6.9 GIS Workshop for Groundwater Resources Assessment .............................. 6-17
7 Groundwater Modeling ........................................................ 7-1
7.1 General ............................................................................................................. 7-1
7.2 Area selection for the groundwater model ...................................................... 7-1 7.3 Structuring the groundwater model ................................................................. 7-2
7.3.1 Model domain .................................................................................... 7-2 7.3.2 Initial grid specification ..................................................................... 7-2 7.3.3 Layer specification ............................................................................ 7-3 7.3.4 Boundary specification ...................................................................... 7-4 7.3.5 Layer properties ................................................................................. 7-5 7.3.6 Parameter specification ..................................................................... 7-5
iv
7.4 Result of model calculation ........................................................................... 7-16 7.4.1 Dry cell ............................................................................................ 7-16 7.4.2 Final results of the model simulation .............................................. 7-17
8 Socio-Economic Survey ...................................................... 8-1
8.1 Introduction ..................................................................................................... 8-1 8.1.1 Background and objectives................................................................ 8-2 8.1.2 Methodology and survey items ......................................................... 8-2
8.2 Development plan and related laws ................................................................. 8-2 8.2.1 National level (Federal Democratic Republic of Ethiopia) ............... 8-2 8.2.2 Oromia Region .................................................................................. 8-5
8.3 Socio-economic conditions in the region ........................................................ 8-5 8.3.1 Population and demographic characteristics ..................................... 8-6 8.3.2 Local administrative divisions ........................................................... 8-9 8.3.3 Regional economy ........................................................................... 8-11
8.4 Results of the socio-economic survey ........................................................... 8-18 8.4.1 Interview surveys of woreda water supply situation ....................... 8-36 8.4.2 Interview surveys of target small town water supply system .......... 8-42 8.4.3 Sample household surveys .............................................................. 8-46 8.4.4 Other surveys ................................................................................... 8-54
9 Basic Survey for Water Supply Planning of Small Towns .................................................................................. 9-1
9.1 Introduction ..................................................................................................... 9-1 9.1.1 Background and objectives................................................................ 9-1 9.1.2 Methodology and survey items ......................................................... 9-1
9.2 Small town profiles .......................................................................................... 9-4
9.3 Results of water use survey ........................................................................... 9-13 9.3.1 Interview survey of water supply situation in Woreda .................... 9-13 9.3.2 Interview survey of water supply situation in small Towns ............ 9-14 9.3.3 Sample household survey ................................................................ 9-16
9.4 Analysis of survey results on existing water facility conditions ................... 9-26 9.4.1 Water supply conditions and hardship ............................................ 9-34 9.4.2 Current conditions of existing water supply facilities and its
issues................................................................................................ 9-39 9.4.3 Water sources .................................................................................. 9-51
9.5 Operation and Maintenance (O&M) of Water Supply Facilities .................. 9-51 9.5.1 Policies, rules, and regulations on O&M ......................................... 9-51 9.5.2 Current conditions of O&M in target small towns .......................... 9-59 9.5.3 Ability and actual performance of water committee/office
for O&M .......................................................................................... 9-62 9.5.4 Overall identified issues on management and O&M of
water supply facilities ...................................................................... 9-64
10 Environmental and Social Consideration .......................... 10-1
10.1 Introduction ................................................................................................... 10-1
v
10.2 Outline of the Project components ................................................................ 10-1
10.3 Outline of the water supply plans .................................................................. 10-1
10.4 Alternative for rural kebeles .......................................................................... 10-4
10.5 Environmental and social conditions in the Project area ............................... 10-5 10.5.1 Natural environment ........................................................................ 10-5 10.5.2 Environmental pollution .................................................................. 10-8 10.5.3 Social environment .......................................................................... 10-9
10.6 Classification of environmental category .................................................... 10-12 10.6.1 JICA category ................................................................................ 10-12 10.6.2 Category by Ethiopian guideline ................................................... 10-12
10.7 Environmental system and organizations in Ethiopia ................................. 10-13
10.8 Alternatives including zero options ............................................................. 10-14
10.9 Scoping ........................................................................................................ 10-17
10.10 TOR of environmental and social consideration ......................................... 10-18
10.11 Result of environmental and social impact assessment ............................... 10-18 10.11.1 Local economy (creation of unemployment) ................................ 10-18 10.11.2 Environmental and social impact by heavy vehicle ...................... 10-19 10.11.3 Local Conflict ................................................................................ 10-21
10.12 Environmental impact assessment (Preliminary EIA) ................................. 10-22
10.13 Mitigation .................................................................................................... 10-25 10.14 Environmental monitoring plan ................................................................... 10-25
10.15 Discussions with stakeholder ....................................................................... 10-28
10.16 Conclusion ................................................................................................... 10-28
11 Hydrology and Hydrogeology Analysis around Lake Beseka .............................................................................. 11-1
11.1 Introduction ................................................................................................... 11-1
11.2 The Lake Beseka Issues ................................................................................. 11-1 11.2.1 Current situation of Lake Beseka .................................................... 11-1 11.2.2 Water level of Lake Beseka and change in outflow ........................ 11-3 11.2.3 Irrigation plan and current situation around Lake Beseka ............... 11-8
11.3 Topography, geology and geological structure ........................................... 11-11 11.3.1 Topography.................................................................................... 11-11 11.3.2 Geology ......................................................................................... 11-17 11.3.3 Geological structure ....................................................................... 11-39
11.4 Hydrogeology .............................................................................................. 11-40 11.4.1 Aquifer classification and groundwater flow ................................ 11-40 11.4.2 Hydrogeological map and cross-sections ...................................... 11-48
11.5 Inflow situation of springs and irrigation water .......................................... 11-51 11.5.1 Ageing of spring inflow by satellite image analysis ..................... 11-51 11.5.2 Results of water quality testing ..................................................... 11-58 11.5.3 Estimation of irrigation return flow ............................................... 11-71
vi
11.6 Analyses on Groundwater Recharge and Movement for Lake Beseka Area ............................................................................................................. 11-91 11.6.1 Irrigation farms around Lake Beseka ............................................ 11-91 11.6.2 Return flow from the irrigation area .............................................. 11-91 11.6.3 The result of 1st analysis (criteria) ................................................. 11-92 11.6.4 The result of 2nd analysis (criteria) ................................................ 11-93 11.6.5 The result of 3rd analysis (Criteria) ................................................ 11-94 11.6.6 Estimation of the groundwater fluctuation in the irrigation
farms by model .............................................................................. 11-96 11.6.7 Comparison between the irrigation return flow and water
level rise in Lake Beseka ............................................................... 11-99
11.7 Discussions .................................................................................................. 11-99
APPENDICES
Minutes of Meeting (M/M)
M/M on the Inception Report
M/M on the Progress Report 1
M/M on the Progress Report 2
M/M on the Interim Report
M/M on the Draft Final Report
Confirmation Letters
Confirmation of Handing over of JICA Funded Equipment
Confirmation of Temporary Handover of Equipment
Confirmation of Return of Equipment
vii
List of Tables
Page: Table 1.1.1: Number of Meteorological Stations in the Middle Awash River
Basin .............................................................................................................. 1-2 Table 1.1.2: Monthly Mean Evaporation at 11 Observatories ........................................... 1-8 Table 1.1.3: Comparison between Annual Rainfall and Evaporation ................................ 1-9 Table 1.1.4: Period of Collection of the Climatic Data .................................................... 1-10 Table 1.1.5: Temperature, Relative Humidity, and Sunshine Hours at Several
Stations in and around the Middle Awash River Basin .............................. 1-11 Table 1.2.1: List of Hydrological Stations ....................................................................... 1-14 Table 1.2.2: Mean 10-day Runoff at Major Stations on the Middle Awash .................... 1-15 Table 1.3.1: Summary of Sub-basins ............................................................................... 1-18 Table 1.3.2: Selected Stations for BFI Calculation .......................................................... 1-22 Table 1.3.3: Calculated BFI Values from Flow Separation Analysis .............................. 1-23 Table 1.3.4: Thiessen Ratio for Selected 12 Stations’ Catchments .................................. 1-25 Table 1.3.5: Mean Annual Runoff and Rainfall for Selected Stations ............................. 1-25 Table 1.3.6: Annual Groundwater Recharge in 12 Stations’ Catchments ........................ 1-26 Table 1.3.7: Thiessen Ratio for Sub-basins ...................................................................... 1-28 Table 1.3.8: Result of Groundwater Recharge Estimation by Sub-basins ....................... 1-28 Table 1.3.9: Water Balance in Sub-basins ........................................................................ 1-29 Table 2.1.1: Stratigraphy in Adama Town-Mt. Boseti ....................................................... 2-2 Table 2.1.2: Geological Succession along Adama Town-Mt. Boseti ................................. 2-6 Table 2.1.3: Geological Succession along Lake Koka – Hurita Town – Sire
Town .............................................................................................................. 2-7 Table 2.2.1: Stratigraphy in Kone-Mt. Fentale and its Surrounding Areas ...................... 2-25 Table 2.2.2: Geological Succession along Kone-Mt. Fentale .......................................... 2-27 Table 2.2.3: Geological Succession along Mt. Fentale – Awash Town ........................... 2-28 Table 2.3.1: Stratigraphy in Mojo Town-Arerti Town-Debre Birhan Town and
Surrounding Areas ....................................................................................... 2-45 Table 2.3.2: Mojo Town-Arerti Town -Debre Birhan Town ........................................... 2-51 Table 2.3.3: Mojo Town – Chefe Donsa Town – Debre Birhan Town ............................ 2-52 Table 2.3.4: Arerti Town – Melka Jiro Town .................................................................. 2-56 Table 2.4.1: Stratigraphy in Awash Town-Asebe Teferi Town ....................................... 2-62 Table 2.4.2: Geological Succession of Mieso Town-Asebe Teferi Town-Arba
Bekete Town ............................................................................................... 2-68 Table 2.4.3: Geological Succession of Bordede Town – Bube Town – Belo
Town ............................................................................................................ 2-69 Table 2.4.4: Geological Succession of Adami Hara –Kora Town -Debala Town ........... 2-72 Table 2.4.5: Geological Succession of Asebot Town – Beka Town. ............................... 2-73 Table 2.4.6: Geological Succession of Awash Town – Mieso Town .............................. 2-75 Table 2.5.1: Correlation of stratigraphy in the study area ................................................ 2-82 Table 2.6.1: Correlation of stratigraphy with existing documents and maps ................... 2-84 Table 3.2.1: Satellite Image for Interpretation ................................................................... 3-4 Table 3.3.1: List of References ......................................................................................... 3-12 Table 3.3.2: Number of Data by Parameter in Well Database (with coordinates) ........... 3-16 Table 3.3.3: Existing Well Data in West Hararge Zone ................................................... 3-17 Table 3.3.4: Existing Well Data Around Lake Beseka .................................................... 3-19 Table 3.3.5: Existing Well Data in Arsi Zone .................................................................. 3-21 Table 3.3.6: Existing Well Data in East Shewa Zone, Amhara Region and others ......... 3-23
viii
Table 3.4.1: 1:2,000,000 Hydrogeological Map - Aquifer Classification and Definitions ................................................................................................... 3-35
Table 3.4.2: Modified Hydrogeological Map - Aquifer Classifications and Definitions ................................................................................................... 3-35
Table 3.5.1: Sampling List ............................................................................................... 3-39 Table 3.5.2: Previous Water Quality Standard of Ethiopia .............................................. 3-43 Table 3.5.3: New Water Quality Standard of Ethiopia and WHO ................................... 3-44 Table 3.5.4: List of Sampling Points in Dry Season 2015 ............................................... 3-62 Table 4.2.1: Summary of numbers of geophysical survey ................................................. 4-2 Table 4.3.1: Summary of the Electrodes Spacing by Schlumberger Array ...................... 4-12 Table 4.3.2: Specification of STING R1 .......................................................................... 4-13 Table 4.3.3: Specifications of TEM System ..................................................................... 4-18 Table 4.3.4: Sampling Gate Time Table........................................................................... 4-19 Table 4.4.1: Summary of the Resistivity Depends on the Different Lithology ................ 4-30 Table 4.4.2: Results of interpretation of each site ............................................................ 4-31 Table 5.1.1: Basic Specifications of the Observation Well ................................................ 5-1 Table 5.2.1: Outline of Observation Wells ......................................................................... 5-3 Table 5.2.2: Information of Observation Well Site ............................................................ 5-3 Table 5.2.3: Lithological Condition of AWBH-1 .............................................................. 5-5 Table 5.2.4: Lithological Condition of AWBH-2 .............................................................. 5-6 Table 5.2.5: Lithological Condition of AWBH-3 .............................................................. 5-6 Table 5.2.6: Lithological Condition of AWBH-4N ............................................................ 5-7 Table 5.2.7: Lithological Condition of AWBH-5 .............................................................. 5-7 Table 5.2.8: Lithological Condition of AWBH-6 .............................................................. 5-8 Table 5.2.9: Lithological Condition of AWBH-7 .............................................................. 5-9 Table 5.2.10: Lithological Condition of AWBH-8 ............................................................ 5-9 Table 5.2.11: Lithological Condition of AWBH-9 ............................................................ 5-9 Table 5.2.12: Lithological Condition of AWBH-11 ........................................................ 5-10 Table 5.2.13: Lithological Condition of AWBH-12 ........................................................ 5-11 Table 5.2.14: Specification of Borehole Logging ............................................................ 5-11 Table 5.2.15: Resistivity Values According to Depth at AWBH-1.................................. 5-11 Table 5.2.16: Resistivity Values According to Depth at AWBH-2.................................. 5-12 Table 5.2.17: Resistivity Values According to Depth at AWBH-3.................................. 5-13 Table 5.2.18: Resistivity Values According to Depth at AWBH-4N ............................... 5-13 Table 5.2.19: Resistivity Values According to Depth at AWBH-5.................................. 5-14 Table 5.2.20: Resistivity Values According to Depth at AWBH-6.................................. 5-14 Table 5.2.21: Resistivity Values According to Depth at AWBH-9.................................. 5-15 Table 5.2.22: Resistivity Values According to Depth at AWBH-11................................ 5-16 Table 5.2.23: Result of Chip Sample Observation of AWBH-1 ...................................... 5-18 Table 5.2.24: Result of Chip Sample Observation of AWBH-2 ...................................... 5-19 Table 5.2.25: Result of Chip Sample Observation of AWBH-3 ...................................... 5-21 Table 5.2.26: Result of Chip Sample Observation of AWBH-4N ................................... 5-22 Table 5.2.27: Result of Chip Sample Observation of AWBH-5 ...................................... 5-23 Table 5.2.28: Result of Chip Sample Observation of AWBH-6 ...................................... 5-24 Table 5.2.29: Result of Chip Sample Observation of AWBH-7 ...................................... 5-26 Table 5.2.30: Result of Chip Sample Observation of AWBH-8 ...................................... 5-27 Table 5.2.31: Result of Chip Sample Observation of AWBH-9 ...................................... 5-29 Table 5.2.32: Result of Chip Sample Observation of AWBH-11 .................................... 5-30 Table 5.2.33: Result of Chip Sample Observation of AWBH-12 .................................... 5-32 Table 5.2.34: Correlation of Resistivity Structure and the Results of Drilling in
Each Point ................................................................................................... 5-32
ix
Table 5.3.1: Specification of Pumping Test ..................................................................... 5-34 Table 5.3.2: Pumping Volume and Drawdown Volume of Step-drawdown Test
(1) ................................................................................................................ 5-36 Table 5.3.3: Pumping Volume and Drawdown Volume of Step-drawdown Test
(2) ................................................................................................................ 5-36 Table 5.3.4: Well Efficiency Calculation Result of AWBH-1 ......................................... 5-37 Table 5.3.5: Well Efficiency Calculation Result of AWBH-4N ...................................... 5-38 Table 5.3.6: Well Efficiency Calculation Result of AWBH-5 ......................................... 5-39 Table 5.3.7: Well Efficiency Calculation Result of AWBH-6 ......................................... 5-40 Table 5.3.8: Well Efficiency Calculation Result of AWBH-9 ......................................... 5-41 Table 5.3.9: Well Efficiency Calculation Result of AWBH-11 ....................................... 5-42 Table 5.3.10: Hydrologic Constant of Aquifer (1) ........................................................... 5-64 Table 5.3.11: Hydrologic Constant of Aquifer (2) ........................................................... 5-65 Table 5.3.12: Results of Water Quality Analysis during Pumping Tests ......................... 5-65 Table 5.4.1: Stratigraphic Sequence of Drilling Point (AWBH-1) .................................. 5-66 Table 5.4.2: Stratigraphic Sequence of Drilling Point (AWBH-1) .................................. 5-66 Table 5.4.3: Stratigraphic Sequence of Drilling Point (AWBH-3) .................................. 5-67 Table 5.4.4: Stratigraphic Sequence of Drilling Point (AWBH-4N) ............................... 5-67 Table 5.4.5: Stratigraphic Sequence of Drilling Point (AWBH-5) .................................. 5-67 Table 5.4.6: Stratigraphic Sequence of Drilling Point (AWBH-6) .................................. 5-68 Table 5.4.7: Stratigraphic Sequence of Drilling Point (AWBH-9) .................................. 5-69 Table 5.4.8: Stratigraphic Sequence of Drilling Point (AWBH-11) ................................ 5-69 Table 5.4.9: Stratigraphic Sequence of Drilling Point (AWBH-12) ................................ 5-70 Table 5.4.10: Summary of Aquifer and Drilling Wells (1) .............................................. 5-70 Table 5.4.11: Summary of Aquifer and Drilling Wells (2) .............................................. 5-71 Table 5.4.12: Characteristic of Groundwater Level of Each Well ................................... 5-71 Table 5.4.13: Results of Water Quality Analysis during Pumping Tests (1) ................... 5-72 Table 5.4.14: Results of Water Quality Analysis during Pumping Tests (2) ................... 5-72 Table 6.2.1: Summary of the Investigation regarding the ENGWIS.................................. 6-1 Table 6.2.2: Investigation result of the Current Status of ENGWIS .................................. 6-2 Table 6.3.1: Collected Basic Data ...................................................................................... 6-3 Table 6.3.2: Collected Natural Condition Data .................................................................. 6-4 Table 6.3.3: Collected Social Condition Data .................................................................... 6-5 Table 6.3.4: Collected Groundwater Information .............................................................. 6-6 Table 6.3.5: Collected Groundwater Resource Data .......................................................... 6-7 Table 6.5.1: Example of Required Data in Groundwater Resources Assessment
Works .......................................................................................................... 6-10 Table 6.6.1: System Requirements/Configurations for the GIS/DB ................................ 6-11 Table 6.7.1: Structure and content of the layers in the GIS/DB ....................................... 6-12 Table 6.9.1: Summary of GIS Workshop for Groundwater Resources
Assessment .................................................................................................. 6-17 Table 6.9.2: Questionnaire summary of the GIS workshop ............................................. 6-18 Table 7.3.1: Collected Transmissivity Data ....................................................................... 7-7 Table 7.3.2: Recharge within the Sub-Basin ...................................................................... 7-9 Table 7.3.3: Groundwater Usage Volume ........................................................................ 7-10 Table 8.1.1: Lowest Ranked Countries by Real GNI per Capita ....................................... 8-1 Table 8.1.2: Major Points and Socio-economic Survey Items for 30 Target
Towns ............................................................................................................ 8-2 Table 8.2.1: Succession of Real Economic Growth Rate in Ethiopia in recent
years*1) .......................................................................................................... 8-3 Table 8.3.1: Number of Ethiopian Population and Growth Rate in recent 3 years ............ 8-6
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Table 8.3.2: Population Census Data of each Ethiopian Regional State in 1994, in 2007, and in 2013 ...................................................................................... 8-6
Table 8.3.3: Population of Towns in the Project target area .............................................. 8-6 Table 8.3.4: Population of each 5 ages Category and Urban/Rural Category .................... 8-7 Table 8.3.5: Ratio of Ethnic Groups in Oromia Region ..................................................... 8-8 Table 8.3.6: Ratio of Religions in Oromia Region ............................................................. 8-8 Table 8.3.7: Ratio of Language in Oromia Region ............................................................ 8-8 Table 8.3.8: 18 Zones in Oromia Region ........................................................................... 8-9 Table 8.3.9: Working Population by Gender of the Primary Industry in Oromia
Region ......................................................................................................... 8-11 Table 8.3.10: Cropping Acreage of Major Grains in Oromia Region .............................. 8-12 Table 8.3.11: Number of Livestock in Oromia Region .................................................... 8-12 Table 8.3.12: Distance and Time between the Target Towns and Major
Towns/Cities ................................................................................................ 8-13 Table 8.3.13: Characteristics of legend between the target towns (for Access
Route Map) .................................................................................................. 8-14 Table 8.3.14: City/Town with less electricity coverage ................................................... 8-17 Table 8.3.15: Construction Period and Route for Ethiopia-China Railway Project
from Addis Ababa to Djibouti ..................................................................... 8-18 Table 8.4.1: 30 Target Small Towns in the Project Area ................................................. 8-19 Table 8.4.2: The Summary of the Results of the Socio-economic Surveys ..................... 8-19 Table 8.4.3: Survey Results of Socio-economy and Water Usage in 15 Woredas
over Target Towns ...................................................................................... 8-21 Table 8.4.4: Survey Results of Socio-economy and Water Usage in 30 Target
Towns .......................................................................................................... 8-25 Table 8.4.5: Results of the Sample Household Surveys of 30 Target Towns .................. 8-33 Table 8.4.6: Target Woredas List of 30 Target Towns in this Project ............................. 8-36 Table 8.4.7: Composition Ethnic Group in 15 Woredas for Target Towns ..................... 8-37 Table 8.4.8: Number of Schools in Woredas ................................................................... 8-38 Table 8.4.9: Numbers of Children and the School Attendance in Woredas ..................... 8-38 Table 8.4.10: Composition of Land Use Conditions in Woredas ..................................... 8-39 Table 8.4.11: Main Crops Yield of Agriculture in 2013 in Woredas ............................... 8-40 Table 8.4.12: Number of Livestock in Woredas .............................................................. 8-40 Table 8.4.13: Number of Agriculture and Livestock-related Facilities ............................ 8-41 Table 8.4.14: Number and Type of Water-related Diseases in Woredas ......................... 8-41 Table 8.4.15: Type and Number of Latrine Facilities in Woredas ................................... 8-42 Table 8.4.16: Main Crops Yield in 30 Target Towns ....................................................... 8-43 Table 8.4.17: Number of Livestock in 30 Target Towns ................................................. 8-44 Table 8.4.18: Number of Educational Facilities in 30 Target Towns .............................. 8-45 Table 8.4.19: The Number of Children and the School Attendance in 30 Target
Towns .......................................................................................................... 8-45 Table 8.4.20: Composition of Occupation of Household Survey in 30 Target
Towns .......................................................................................................... 8-48 Table 8.4.21: Water-related Disease Rank of 30 Target Towns ...................................... 8-49 Table 8.4.22: Type and Number of Sanitation Facilities in 30 Target Towns ................. 8-52 Table 8.4.23: Main Information Sources for Sanitation and Hygiene.............................. 8-52 Table 8.4.24: Sugar Factory and a Few Farms in the Middle Awash River Basin .......... 8-54 Table 8.4.25: Socio-economic Survey for Wonji-shoa Sugar Factory ............................. 8-56 Table 8.4.26: Socio-economic Information in Metehara Sugar Factory .......................... 8-58 Table 8.4.27: Social Information for Nura Hera Farm ..................................................... 8-61 Table 9.1.1: Survey Items on Existing Water Supply Facilities ......................................... 9-1
xi
Table 9.1.2: Actual Survey Schedule ................................................................................. 9-3 Table 9.1.3: Contents of Water Use Survey ....................................................................... 9-4 Table 9.2.1: List of Target Towns ...................................................................................... 9-4 Table 9.3.1: Population, Number of Users and Water Coverage Rate in Woreda ........... 9-13 Table 9.3.2: Number and Type of existing Water Source in Woreda .............................. 9-13 Table 9.3.3: Population, Number of Households and Number of Users .......................... 9-14 Table 9.3.4: Number of existing Water Supply Facilities by Water Source Type
of the Town ................................................................................................. 9-15 Table 9.3.5: Number of existing Water Taps and Water Meters ...................................... 9-16 Table 9.3.6: Existing Water Sources in Rainy and Dry seasons ...................................... 9-17 Table 9.3.7: People who Fetch Water .............................................................................. 9-17 Table 9.3.8: Type of Container for Fetching Water ......................................................... 9-17 Table 9.3.9: Distance, Time and Frequency for Fetching Water ..................................... 9-18 Table 9.3.10: Water Consumption by Purpose ................................................................. 9-19 Table 9.3.11: Amount to Pay for Water ........................................................................... 9-20 Table 9.3.12: Percentage of Respondents who Need Improved Water Supply
System ......................................................................................................... 9-20 Table 9.3.13: Water Supply Situation to be Improved ..................................................... 9-21 Table 9.3.14: Water Storage Conditions at Home ............................................................ 9-22 Table 9.3.15: Percentage of Respondents Trained in Hygiene Education ....................... 9-22 Table 9.3.16: Water Treatment Method ........................................................................... 9-23 Table 9.3.17: Percentage of Respondents or their Families who Suffered
Diarrhea within Two Weeks ....................................................................... 9-23 Table 9.3.18: Amount of Respondents who Have the Intention to Contribute ................ 9-24 Table 9.3.19: Percentage of Respondents with the Intension to Pay for Water ............... 9-24 Table 9.3.20: Amount of Respondents with the Intension to pay for Water .................... 9-25 Table 9.4.1: Survey Results on existing Water Supply Facilities’ Conditions and
its’ Operation & Maintenance Situation ...................................................... 9-27 Table 9.4.2: Comparison of Population Data ................................................................... 9-34 Table 9.4.3: Number of Users .......................................................................................... 9-35 Table 9.4.4: Water Consumption Volume ........................................................................ 9-36 Table 9.4.5: Water Consumption Volume from Water Supply Facility ........................... 9-38 Table 9.4.6: Types of Water Supply System .................................................................... 9-39 Table 9.4.7: Brand of Existing Engine of Generators and Pumps .................................... 9-41 Table 9.4.8: Operating Hour of Existing Pump ................................................................ 9-43 Table 9.4.9: Numbers of Water Points and Water Meters................................................ 9-45 Table 9.4.10: The Sufficiency Rate of Existing Water Supply Facilities to Water
Demand ....................................................................................................... 9-47 Table 9.4.11: Safe Water Consumption ........................................................................... 9-48 Table 9.4.12: Construction Ages of Borehole .................................................................. 9-49 Table 9.4.13: Used Years of existing Pump ..................................................................... 9-50 Table 9.4.14: Used Years of existing Diesel Generator ................................................... 9-50 Table 9.4.15: Water Tariff by Power Type ...................................................................... 9-50 Table 9.4.16: Main Water Source of Water Supply System in Target Small
Town ............................................................................................................ 9-51 Table 9.5.1: Comparison of existing Water Supply System Type ................................... 9-52 Table 9.5.2: Organizations related to Water Supply Service ........................................... 9-53 Table 9.5.3: Number of Staff and Budget of OWMEB .................................................... 9-55 Table 9.5.4: Number of Staff and Budget of ZWMEO .................................................... 9-56 Table 9.5.5: Number of Staff and Budget of WWMEO ................................................... 9-57 Table 9.5.6: Equipment in WWMEO ............................................................................... 9-57
xii
Table 9.5.7: Operation and Maintenance Management Organization, Meeting Situation and Income Record Documentation Situation ............................. 9-59
Table 9.5.8: Water Tariff of Target Towns ...................................................................... 9-61 Table 9.5.9: Type and Number of Staff of O&M Organization ....................................... 9-63 Table 9.5.10: Revenue, Expense and Remaining Funds (unit: birr) ................................. 9-64 Table 9.5.11: Sample of Technical Information Sheet ..................................................... 9-66 Table 10.3.1: Allocation of water supply amount between new and current
facilities ....................................................................................................... 10-2 Table 10.3.2: Outline of construction plan of new water supply facilities ....................... 10-4 Table 10.3.3: Outline of renewal plan of existing water supply facilities ........................ 10-4 Table 10.4.1: Implementation cost ................................................................................... 10-5 Table 10.5.1: Data on air temperature, relative humidity and sunshine hours
from weather stations in and around the Middle Awash River Basin ......... 10-6 Table 10.5.2: Population Census Data of each Ethiopian Regional State in 1994,
in 2007, and in 2013 .................................................................................... 10-9 Table 10.5.3: Ethnic composition in each woreda in the Project area............................ 10-10 Table 10.5.4: Religion in the Oromia region .................................................................. 10-10 Table 10.5.5: Language spoken in the Project area ........................................................ 10-11 Table 10.5.6: Planted area of agriculture productions .................................................... 10-11 Table 10.6.1: Applicability of Sensitive Characteristics and Areas on the
Environment and Society Designated by JICA Guidelines (April 2010) .......................................................................................................... 10-12
Table 10.7.1: List of projects that require a preliminary study ...................................... 10-14 Table 10.8.1: Impacts comparison between with- and without Project ......................... 10-14 Table 10.9.1: Scoping matrix ......................................................................................... 10-17 Table 10.10.1: Summary of items of environmental and social consideration .............. 10-18 Table 10.11.1: Standards on air pollution and noise/vibration in Ethiopia .................... 10-20 Table 10.12.1: Assessed impacts by the water supply plan ........................................... 10-23 Table 10.13.1: Mitigation measures for negative impacts ............................................. 10-25 Table 10.14.1: Environmental monitoring plan ............................................................. 10-26 Table 11.2.1: Water Intake Volume by Abadir Farm ..................................................... 11-10 Table 11.2.2: Water Intake Volume by Nura Hira Farm ................................................ 11-10 Table 11.2.3: Major Irrigation Schemes in the Lake Beseka Watershed ....................... 11-11 Table 11.3.1: Classification and Characteristics of Topography around Lake
Beseka ....................................................................................................... 11-11 Table 11.3.2: Geological stratigraphy around Lake Beseka and correlation with
other areas ................................................................................................. 11-39 Table 11.4.1: Existing Wells and JICA Wells with Columnar Section around
Lake Beseka .............................................................................................. 11-45 Table 11.4.2: Aquifer Unit Classification and Characteristics around Lake
Beseka ....................................................................................................... 11-47 Table 11.5.1: Data used for the Analysis........................................................................ 11-52 Table 11.5.2: Temperature Result during the Water Quality Survey (9th March
2014) .......................................................................................................... 11-57 Table 11.5.3: List of Sampling Points around Lake Beseka .......................................... 11-59 Table 11.5.4: List of Existing Water Quality Data (around Lake Beseka) .................... 11-60 Table 11.5.5: Results and List of Isotope Analysis ........................................................ 11-68 Table 11.5.6: List of Points for Tritium Analysis .......................................................... 11-71 Table 11.5.7: Irrigation Efficiency of Abadir by Previous Surveys ............................... 11-73 Table 11.5.8: Duration and Kc Values by Growth Stages.............................................. 11-75 Table 11.5.9: Effective Rainfall in Abadir Farm ............................................................ 11-76
xiii
Table 11.5.10: Annual Irrigation Efficiency in Abadir Farm ......................................... 11-76 Table 11.5.11: Mean Annual Water Balance in the Lake Beseka (ELSA 33.4
km2) ........................................................................................................... 11-79 Table 11.5.12: Mean Annual Water Balance in the Lake Beseka (ELSA 4 km2) ....... 11-79 Table 11.5.13: Sensitivity of ELSA to Climatic Conditions .......................................... 11-82 Table 11.5.14: Mean Annual Water Balance in the Lake Beseka with 35 MCM
Return Flow ............................................................................................... 11-83 Table 11.5.15: Mean Annual Water Balance in the Lake Beseka with 46.2 MCM
Return Flow ............................................................................................... 11-84 Table 11.5.16: Mean Annual Water Balance in the Lake Beseka with 102 MCM
Return Flow ............................................................................................... 11-84 Table 11.5.17: Mean Annual Water Balance in the Lake Beseka with 35 MCM
Return Flow (without loss “Y”) ................................................................ 11-87 Table 11.5.18: Mean Annual Water Balance in the Lake Beseka with 102 MCM
Return Flow (without loss “Y”) ................................................................ 11-87 Table 11.6.1: Estimated Return Flow from Irrigation to Lake Beseka by MoWIE ....... 11-91 Table 11.6.2: Water Intake Amount from Awash River to Each Irrigation Farm .......... 11-95
xiv
List of Figures
Page: Figure 1.1.1: Meteorological Stations in and around the Middle Awash River
Basin .............................................................................................................. 1-1 Figure 1.1.2: List of Rainfall Stations with Available Data ............................................... 1-3 Figure 1.1.3: Historical Trend of Annual Rainfall at Addis Ababa (1951–2011) .............. 1-4 Figure 1.1.4: Historical Trend of Annual Rainfall at Debre Zeit (1952–2011) ................. 1-4 Figure 1.1.5: Historical Trend of Annual Rainfall at Kulumsa (1972–2012) .................... 1-4 Figure 1.1.6: Isohyetal Map of the Middle Awash River Basin ......................................... 1-5 Figure 1.1.7: Seasonal Drifting of the ITCZ in Africa ....................................................... 1-6 Figure 1.1.8: Relationship between Elevation and Annual Rainfall Amount .................... 1-6 Figure 1.1.9: Historical Trend of Annual Rainfall in the Middle Awash River
Basin .............................................................................................................. 1-7 Figure 1.1.10: List of Evaporation Observatories with Available Data ............................. 1-7 Figure 1.1.11: Monthly Evaporation at Three Observatories ............................................. 1-8 Figure 1.1.12: Relationship between Elevation and Annual Evaporation .......................... 1-9 Figure 1.1.13: Climatic Zone Classification in the Middle Awash River Basin .............. 1-10 Figure 1.1.14: Historical Trend of Temperature at Addis Ababa (1951–2012) ............... 1-11 Figure 1.1.15: Historical Trend of Temperature at Debre Zeit (1953–2012) ................... 1-11 Figure 1.1.16: Monthly Temperature and Relative Humidity at Several Stations
in and around the Middle Awash River Basin ............................................ 1-12 Figure 1.1.17: Monthly Reference Evapotranspiration (ETo) in and around the
Middle Awash River Basin ......................................................................... 1-13 Figure 1.2.1: Mean 10-day Runoff Hydrograph at Major Stations on the Middle
Awash .......................................................................................................... 1-15 Figure 1.3.1: Procedure of the Hydrological Analysis ..................................................... 1-17 Figure 1.3.2: Basin Division for Groundwater Recharge Estimation .............................. 1-18 Figure 1.3.3: Precipitation and Process of River Water Formation.................................. 1-19 Figure 1.3.4: Location Map of Selected Stations for BFI Calculation ............................. 1-22 Figure 1.3.5: Examples of Base Flow Separation Results ................................................ 1-23 Figure 1.3.6: Relationship between Catchment Area and BFI Values ............................. 1-24 Figure 1.3.7: Relationship between Catchment Area and Runoff Coefficient ................. 1-26 Figure 2.1.1: Location map of outcrops ............................................................................. 2-3 Figure 2.1.2: Kelefa River (L-AB21) ................................................................................. 2-4 Figure 2.1.3: Tulu (L-AB07) (top left), Chefeko (L-AB08)(top light), Mt.Debeso
(L-AB09)(bottom) ......................................................................................... 2-5 Figure 2.1.4: Sire (L-AB35) (top), Boko (L-AB11) (bottom) ............................................ 2-8 Figure 2.1.5: Koka Dam (L-AB02) (top), Rukecha (L-MAD40) (bottom) ........................ 2-9 Figure 2.1.6: River Robi L-AB28) .............................................................................. 2-10 Figure 2.1.7: Bofa (L-AB25) (top left), Holly Spring (L-AB39) (top right),
Weleso River (L-AB43) (bottom) ............................................................... 2-11 Figure 2.1.8: Photos of Thin Sections of Sample Number140419-1 ............................... 2-12 Figure 2.1.9: Jogo (L-AB06) (top), West of Bofa Town (L-AB22) (bottom) .................. 2-13 Figure 2.1.10: Photos of Thin Sections of Sample Number 140414-1 ............................ 2-14 Figure 2.1.11: Photos of Thin Sections of Sample Number 140414-2 ............................ 2-15 Figure 2.1.12: Photos of Thin Sections of Sample Number 140414-5 ............................ 2-16 Figure 2.1.13: Photos of Thin Sections of Sample Number 140414-6 ............................ 2-17 Figure 2.1.14: Photos of Thin Sections of Sample Number140419-3 ............................. 2-18 Figure 2.1.15: Photos of Thin Sections of Sample Number140419-5 ............................. 2-19
xv
Figure 2.1.16: Northeastern Cliff of Gademsa Caldera (L-AB05) ................................... 2-19 Figure 2.1.17: Boru River (L-AB19) (top), Sire (L-AB37) (bottom) .............................. 2-20 Figure 2.1.18: Gambedra (L-AB38) ................................................................................. 2-21 Figure 2.1.19: Welensu (L-AB17) (left), Mt.Boseti (L-AB29) (right)............................. 2-21 Figure 2.1.20: Madiga, (L-MAD37) (top), Lake Koka (L-AB10) (bottom) .................... 2-22 Figure 2.1.21: Harorecha (L-AB32) (left), Haribona (L-AB42) (right) ........................... 2-23 Figure 2.1.22: Waka Bute (L-AB04) (top), Miesa (L-AB03) (bottom) ........................... 2-24 Figure 2.2.1: Bosena (L-KF02) Bokan ............................................................................. 2-26 Figure 2.2.2: Photos of Thin Sections of Sample Number 140415-4 .............................. 2-29 Figure 2.2.3: Southeastern Foot of Mt. Fentale (L-KF39) ............................................... 2-30 Figure 2.2.4: Sobebor (L-KF23) (top), Boru Alore (L-KF18) (middle) and
Dinbiba (L-KF30) (bottom) ........................................................................ 2-31 Figure 2.2.5: Photos of Thin Sections of Sample Number140417-5 ............................... 2-32 Figure 2.2.6: Dodose Use (L-KF20) (top) and Bogda (L-KF25) (bottom) ...................... 2-33 Figure 2.2.7: Kone (L-KF13) (top) and Ofe, Southwestern Foot of Kone Caldera
(L-KF03) (bottom) ...................................................................................... 2-34 Figure 2.2.8: Photos of Thin Sections of Sample Number 140415-2 .............................. 2-35 Figure 2.2.9: Korke (L-KF10) .......................................................................................... 2-36 Figure 2.2.10: Dinbiba (L-KF31) (top), Southern Foot of Mt. Fentale (L-KF30)
(bottom left) and Southern Foot of Mt. Fentale (L-KF34) (bottom right) ............................................................................................................ 2-37
Figure 2.2.11: Photos of Thin Sections of Sample Number 140415-3 ............................ 2-38 Figure 2.2.12: Photos of Thin Sections of Sample Number140417-1 ............................. 2-39 Figure 2.2.13: Photos of Thin Sections of Sample Number140417-2 ............................. 2-40 Figure 2.2.14: Photos of Thin Sections of Sample Number140417-4 ............................. 2-41 Figure 2.2.15: Boru Alore (L-KF21) ................................................................................ 2-42 Figure 2.2.16: Photos of Thin Sections of Sample Number 140415-1 ............................ 2-43 Figure 2.2.17: Dinbiba (L-KF29) ..................................................................................... 2-43 Figure 2.3.1: Balchi (L-MAD14) (top), Balchi (L-MAD15) (bottom) ............................ 2-46 Figure 2.3.2: Aroge Minjar (L-MAD29) (top and middle), Chifey (L-MAD12)
(bottom left), Gina Ager (L-MAD30) (bottom right) ................................. 2-48 Figure 2.3.3: Aroge Minjar (L-MAD29) (top), Balchi (L-MAD14) (middle left),
Zengo (L-MAD10) (middle right), Gobemsa (L-MAD25) (bottom) .......... 2-49 Figure 2.3.4: Gidm Asfa (L-MAD21) (top), Zongo (L-MAD10) (bottom left),
Megezeze (L-MAD24) (bottom right) ........................................................ 2-50 Figure 2.3.5: Mt. Bokan (L-MAD09) ............................................................................... 2-53 Figure 2.3.6: Samasembet (L-MAD11) ............................................................................ 2-54 Figure 2.3.7: Aroge Minjar (L-MAD29) .......................................................................... 2-54 Figure 2.3.8: Kunche (L-MAD06) ................................................................................... 2-55 Figure 2.3.9: Jolo (L-MAD41) ......................................................................................... 2-57 Figure 2.3.10: Chefe Donsa (L-MAD02) ......................................................................... 2-58 Figure 2.3.11: Mt. Zikwala (L-MAD41) .......................................................................... 2-58 Figure 2.3.12: Argoba (L-MAD04) (top), Lake Haro Meja (L-MAD01) (bottom
left), Lake Haro Kilole (L-MAD39) (bottom right) .................................... 2-59 Figure 2.3.13: Wubit Ager, Kersa River (L-MAD19) ...................................................... 2-60 Figure 2.3.14: Borchota (L-MAD23) ............................................................................... 2-60 Figure 2.3.15: Borchota (L-MAD23) ............................................................................... 2-61 Figure 2.4.1: Arba Rekete (L-AA59) (top), Komena (L-AA35) (bottom left) and
Cheleleka (L-AA09) (bottom right) ............................................................ 2-63 Figure 2.4.2: Huse Ridge (L-AA53) ................................................................................. 2-64 Figure 2.4.3: Photos of Thin Sections of Sample Number140416-1 ............................... 2-65
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Figure 2.4.4: Photos of Thin Sections of Sample Number140416-2 ............................... 2-66 Figure 2.4.5: Asebe Teferi (L-AA57) (top), Agemti (L-AA20) (bottom) ........................ 2-67 Figure 2.4.6: Gara Gumbi (L-AA06) (top) and Dalecha (L-AA46) (bottom) .................. 2-70 Figure 2.4.7: Type Locality (L-AA30) (top) and its Vicinity (L-AA29) (bottom) .......... 2-71 Figure 2.4.8: Type Locality (L-KF43) (top) and Gara Gumbi Rasa (L-AA10)
(bottom) ....................................................................................................... 2-74 Figure 2.4.9: Type Locality, Awash River (L-KF42) (top) and Komena
(L-AA40) (bottom) ...................................................................................... 2-76 Figure 2.4.10: Photos of Thin Sections of Sample Number 140416-4 ............................ 2-77 Figure 2.4.11: Type Locality, Riv. Jejeba (L-AA03) ....................................................... 2-78 Figure 2.4.12: Type Locality, Adami Hara (L-AA33) (top), Buri Korkoda Ridge
(L-AA22) (bottom left) and Awash Arba (L-KF40) (bottom right) ........... 2-79 Figure 2.4.13: Type Locality, Mt. Asebot (L-AA44) (top), Kulbas (L-AA38)
(bottom left) and Aneno (L-AA21) (bottom right) ..................................... 2-80 Figure 2.4.14: Awash River (L-KF41) ............................................................................. 2-81 Figure 2.7.1: “En Echelon” arrangement of the active volcano-tectonic axis
within the northern part of the Ethiopian rift (after Elc Electroconsult and Geotermica Italiana, 1987) ........................................... 2-86
Figure 2.8.1: Elevation Map of the Study Area ................................................................ 2-88 Figure 2.8.2: Stages in the Development of the Ethiopian Rift (after Kazmin and
Berhe, 1978) ................................................................................................ 2-89 Figure 3.1.1: Major Basins in Ethiopia .............................................................................. 3-1 Figure 3.1.2: The Central Sector of the MER .................................................................... 3-2 Figure 3.1.3: Digital Elevation Model of the Middle Awash River Basin ......................... 3-3 Figure 3.1.4: River System of the Middle Awash .............................................................. 3-3 Figure 3.2.1: SPOT Satellite Image .................................................................................... 3-5 Figure 3.2.2: ALOS Satellite Image ................................................................................... 3-6 Figure 3.2.3: SRTM DEM (Shaded Relief Model) ............................................................ 3-9 Figure 3.2.4: ASTER DEM .............................................................................................. 3-10 Figure 3.2.5: Topographical Information Map by Satellite Images ................................. 3-11 Figure 3.3.1: Yield and Drilling Depth in West Hararge Zone ........................................ 3-18 Figure 3.3.2: Yield and Drilling Depth in Arsi Zone ....................................................... 3-22 Figure 3.3.3: Yield and Drilling Depth in East Shewa Zone, Amhara Region and
others ........................................................................................................... 3-26 Figure 3.3.4: Location Map of Spring and Hand Dug Wells ........................................... 3-28 Figure 3.4.1: Relation between Yield and Depth of the Existing Wells .......................... 3-30 Figure 3.4.2: Groundwater Level Contour Map in West Hararge Area ........................... 3-31 Figure 3.4.3: Groundwater Level Contour Map in Amhara Area .................................... 3-32 Figure 3.4.4: Groundwater Level Contour Map in East of Lake Koka to Dera
Town ............................................................................................................ 3-32 Figure 3.4.5: Groundwater Level Contour Map in North to East of Lake Koka .............. 3-33 Figure 3.4.6: Groundwater Level Contour Map around Lake Beseka ............................. 3-33 Figure 3.5.1: Location Map of Sampling Points for Water Quality Testing .................... 3-38 Figure 3.5.2: Trilinear diagram ........................................................................................ 3-46 Figure 3.5.3: Trilinear Diagram (All Data) ...................................................................... 3-48 Figure 3.5.4: Trilinear Diagram (River Water) ................................................................ 3-49 Figure 3.5.5: Trilinear Diagram (Wells) ........................................................................... 3-50 Figure 3.5.6: Trilinear Diagram (Spring) ......................................................................... 3-51 Figure 3.5.7: Trilinear Diagram (Lake Water) ................................................................. 3-52 Figure 3.5.8: Trilinear Diagram (Others) ......................................................................... 3-53 Figure 3.5.9: Hexadiagram ............................................................................................... 3-54
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Figure 3.5.10: Distribution Map of Hexadiagram (All data: Data around Lake Beseka at upper left) .................................................................................... 3-56
Figure 3.5.11: Distribution Map of Hexadiagram (River water) ...................................... 3-57 Figure 3.5.12: Distribution Map of Hexadiagram (Wells) ............................................... 3-58 Figure 3.5.13: Distribution Map of Hexadiagram (Spring) .............................................. 3-59 Figure 3.5.14: Distribution Map of Hexadiagram (Lake Water) ...................................... 3-60 Figure 3.5.15: Distribution Map of Hexadiagram (Others) .............................................. 3-61 Figure 3.5.16: Location Map of Sampling Points along Awash River (Short
Rainy and Dry Seasons) .............................................................................. 3-63 Figure 3.5.17: The Hexa diagram of Short Rainy and Dry Season along Awash
River ............................................................................................................ 3-63 Figure 3.5.18: Trilinear diagram of Short Rainy and Dry Season along Awash
River ............................................................................................................ 3-64 Figure 4.1.1: Geophysical Survey Location Map ............................................................... 4-1 Figure 4.2.1: Detail Map of Investigation Site at AW BH-1 .............................................. 4-3 Figure 4.2.2: Detail Map of Investigation Site at AW BH-2 .............................................. 4-3 Figure 4.2.3: Detail Map of Investigation Site at AW BH-3 .............................................. 4-4 Figure 4.2.4: Detail Map of Investigation Site at AW BH-4 .............................................. 4-5 Figure 4.2.5: Detail Map of Investigation Site at AW BH-4N ........................................... 4-5 Figure 4.2.6: Detail Map of Investigation Site at AW BH-5 .............................................. 4-6 Figure 4.2.7: Detail Map of Investigation Site at AW BH-6 .............................................. 4-7 Figure 4.2.8: Detail Map of Investigation Site at AW BH-7 .............................................. 4-8 Figure 4.2.9: Detail Map of Investigation Site at AW B-8 ................................................ 4-8 Figure 4.2.10: Detail Map of Investigation Site at AW BH-9 ............................................ 4-9 Figure 4.2.11: Detail Map of Investigation Site at AW BH-10 ........................................ 4-10 Figure 4.2.12: Detail Map of Investigation Site at AW BH-11 ........................................ 4-10 Figure 4.2.13: Detail Map of Investigation at AW BH-12 ............................................... 4-11 Figure 4.3.1: Schlumberger Array Type ........................................................................... 4-12 Figure 4.3.2: Electric Investigation Instruments .............................................................. 4-13 Figure 4.3.3: Investigation Team ...................................................................................... 4-14 Figure 4.3.4: Example of VES Inversion Analysis by IX1D ........................................... 4-15 Figure 4.3.5: Concept of TEM Investigation .................................................................... 4-17 Figure 4.3.6: TEM Equipment .......................................................................................... 4-18 Figure 4.3.7: Example of Inversion Analysis of TEM Data by “IX1D” .......................... 4-20 Figure 4.4.1: Geophysical Investigation Work ................................................................. 4-21 Figure 4.4.2: Resistivity Structure Cross Sections at AW BH-1 (left) & BH-2
(right) ........................................................................................................... 4-22 Figure 4.4.3: Resistivity Structure Cross Sections at AW BH-3 (left) & BH-4
(right) ........................................................................................................... 4-23 Figure 4.4.4: Resistivity Structure Cross Sections at AW BH-4N (left) & BH-5
(right) ........................................................................................................... 4-24 Figure 4.4.5: Resistivity Structure Cross Sections at AW BH-6 (left) & BH-7
(right) ........................................................................................................... 4-25 Figure 4.4.6: Resistivity Structure Cross Sections at AW BH-8 (left) & BH-9
(right) ........................................................................................................... 4-26 Figure 4.4.7: Resistivity Structure Cross Sections at AW BH-10 (left: SW-NE,
right: NW-SE) ............................................................................................. 4-27 Figure 4.4.8: Resistivity Structure Cross Sections at AW BH-11 (left: SW-NE,
right: NW-SE) ............................................................................................. 4-28 Figure 4.4.9: Resistivity Structure Cross Sections at AW BH-12 .................................... 4-29 Figure 4.4.10: Groundwater resistivity distribution around Lake Beseka ........................ 4-30
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Figure 4.4.11: Recommendation of Drilling Location at AW BH-1 ................................ 4-33 Figure 4.4.12: Recommendation of Drilling Location at AW BH-2 ................................ 4-34 Figure 4.4.13: Recommendation of Drilling Location at AW BH-3 ................................ 4-34 Figure 4.4.14: Recommendation of Drilling Location at AW BH-4N ............................. 4-35 Figure 4.4.15: Recommendation of Drilling Location at AW BH-5 ................................ 4-36 Figure 4.4.16: Recommendation of Drilling Location at AW BH-6 ................................ 4-37 Figure 4.4.17: Recommendation of Drilling Location at AW BH-7 ................................ 4-37 Figure 4.4.18: Recommendation of Drilling Location at AW BH-8 ................................ 4-38 Figure 4.4.19: Recommendation of Drilling Location at AW BH-9 ................................ 4-39 Figure 4.4.20: Recommendation of Drilling Location at AW BH-10 .............................. 4-40 Figure 4.4.21: Recommendation of Drilling Location at AW BH-11 .............................. 4-41 Figure 4.4.22: Recommendation of Drilling Location at AW BH-12 .............................. 4-42 Figure 5.1.1: Structural Figure of the Completed Well ...................................................... 5-2 Figure 5.2.1: Location of the Observation Wells ............................................................... 5-4 Figure 5.2.2: Resistivity Cross-section of Target Drilling Area at AWBH-1 .................. 5-17 Figure 5.2.3: Resistivity Cross-section of Target Drilling Area at AWBH-2 .................. 5-19 Figure 5.2.4: Resistivity Cross-section of Target Drilling Area at AW BH-3 ................. 5-20 Figure 5.2.5: Resistivity Cross-section of Target Drilling Area at AW BH-4N .............. 5-22 Figure 5.2.6: Resistivity Cross-section of Target Drilling Area at AW BH-5 ................. 5-23 Figure 5.2.7: Resistivity Cross-section of Target Drilling Area at AW BH-6 ................. 5-24 Figure 5.2.8: Resistivity Cross-section of Target Drilling Area at AW BH-7 ................. 5-26 Figure 5.2.9: Resistivity Cross-section of Target Drilling Area at AW BH-8 ................. 5-27 Figure 5.2.10: Resistivity Cross-section of Target Drilling Area at AW BH-9 ............... 5-28 Figure 5.2.11: Resistivity Cross-section of the Proposed Drilling Site
(AWBH-11) ................................................................................................. 5-30 Figure 5.2.12: Resistivity Cross-section of Target Drilling Area at AWBH-12 .............. 5-31 Figure 5.3.1: Groundwater Drawdown (SDT) Result of AWBH-1 ................................. 5-37 Figure 5.3.2: Groundwater Drawdown (SDT) Result of AWBH-4N ............................... 5-39 Figure 5.3.3: Groundwater Drawdown (SDT) Result of AWBH-5 ................................. 5-40 Figure 5.3.4: Groundwater Drawdown (SDT) Result of AWBH-6 ................................. 5-41 Figure 5.3.5: Groundwater Drawdown (SDT) Result of AWBH-9 ................................. 5-42 Figure 5.3.6: Groundwater Drawdown (SDT) Result of AWBH-11 ............................... 5-43 Figure 5.3.7: Groundwater Level from Continuous & Recovery Test (S-T curve:
AWBH-1) .................................................................................................... 5-44 Figure 5.3.8: Jacob Straight-line Method (AWBH-1) ...................................................... 5-45 Figure 5.3.9: Theis Curve Method (AWBH-1) ................................................................ 5-45 Figure 5.3.10: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-2) ......................................................................................... 5-46 Figure 5.3.11: Jacob Straight-line Method (AWBH-2) .................................................... 5-46 Figure 5.3.12: Theis Curve Method (AWBH-2) .............................................................. 5-47 Figure 5.3.13: Groundwater Level from Continuous & Recovery Test (S-T
curve : AWBH-3) ........................................................................................ 5-47 Figure 5.3.14: Jacob Straight-line Method (AWBH-3) .................................................... 5-48 Figure 5.3.15: Theis Curve Method (AWBH-3) .............................................................. 5-48 Figure 5.3.16: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-4N) ...................................................................................... 5-49 Figure 5.3.17: Jacob Straight-line Method (AWBH-4N) ................................................. 5-50 Figure 5.3.18: Theis Curve Method (AWBH-4N) ........................................................... 5-50 Figure 5.3.19: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-5) ......................................................................................... 5-51 Figure 5.3.20: Jacob Straight-line Method (AWBH-5) .................................................... 5-51
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Figure 5.3.21: Theis Curve Method (AWBH-5) .............................................................. 5-52 Figure 5.3.22: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-6) ......................................................................................... 5-53 Figure 5.3.23: Jacob Straight-line Method (AWBH-6) .................................................... 5-53 Figure 5.3.24: Theis Curve Method (AWBH-6) .............................................................. 5-54 Figure 5.3.25: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-9) ......................................................................................... 5-54 Figure 5.3.26: Jacob Straight-line Method (AWBH-9) .................................................... 5-55 Figure 5.3.27: Theis Curve Method (AWBH-9) .............................................................. 5-55 Figure 5.3.28: Groundwater Level from Continuous & Recovery Test (S-T
curve : AWBH-11) ...................................................................................... 5-56 Figure 5.3.29: Jacob Straight-line Method (AWBH-11) .................................................. 5-57 Figure 5.3.30: Theis Curve Method (AWBH-11) ............................................................ 5-57 Figure 5.3.31: Groundwater Level from Continuous & Recovery Test (S-T
curve: AWBH-12) ....................................................................................... 5-58 Figure 5.3.32: Jacob Straight-line Method (AWBH-12) .................................................. 5-58 Figure 5.3.33: Theis Curve Method (AWBH-12) ............................................................ 5-59 Figure 5.3.34: Results of Graphical Analysis for Recovery Test (AWBH-1) .................. 5-60 Figure 5.3.35: Results of Graphical Analysis for Recovery Test (AWBH-2) .................. 5-60 Figure 5.3.36: Results of Graphical Analysis for Recovery Test (AWBH-3) .................. 5-61 Figure 5.3.37: Results of Graphical Analysis for Recovery Test (AWBH-4N) ............... 5-61 Figure 5.3.38: Results of Graphical Analysis for Recovery Test (AWBH-5) .................. 5-62 Figure 5.3.39: Results of Graphical Analysis for Recovery Test (AWBH-6) .................. 5-62 Figure 5.3.40: Results of Graphical Analysis for Recovery Test (AWBH-9) .................. 5-63 Figure 5.3.41: Results of Graphical Analysis for Recovery Test (AWBH-11) ................ 5-63 Figure 5.3.42: Results of Graphical Analysis for Recovery Test (AWBH-12) ................ 5-64 Figure 5.5.1: Automatic Water Level Gauge (OYO S&DL mini) ................................... 5-73 Figure 5.5.2: Schematic Figure of the Automatic Water Level Gauge Installation ......... 5-74 Figure 5.5.3: Daily Average of Groundwater Level Change (AWBH-1) ........................ 5-75 Figure 5.5.4: Daily Average of Groundwater Level Change (AWBH-2) ........................ 5-75 Figure 5.5.5: Daily Average of Groundwater Level Change (AWBH-3) ........................ 5-76 Figure 5.5.6: Daily Average of Groundwater Level Change (AWBH-4N) ..................... 5-77 Figure 5.5.7: Daily Average of Groundwater Level Change (AWBH-5) ........................ 5-77 Figure 5.5.8: Daily Average of Groundwater Level Change (AWBH-6) ........................ 5-78 Figure 5.5.9: Daily Average of Groundwater Level Change (AWBH-9) ........................ 5-79 Figure 5.5.10: Daily Average of Groundwater Level Change (AWBH-11) .................... 5-79 Figure 5.5.11: Daily Average of Groundwater Level Change (AWBH-12) .................... 5-80 Figure 6.3.1: An Example of Mapping by the Collected Basic Data ................................. 6-4 Figure 6.3.2: An Example of Mapping by the Collected Natural Condition Data ............. 6-5 Figure 6.3.3: An Example of Mapping by the Collected Social Condition Data ............... 6-6 Figure 6.3.4: An Example of Mapping by the Collected Groundwater
Information .................................................................................................... 6-7 Figure 6.4.1: A Mapping example of Land-cover Classification Result ............................ 6-9 Figure 6.5.1: Conceptual Image of the GIS database ....................................................... 6-10 Figure 6.7.1: Interface of the GIS/DB .............................................................................. 6-12 Figure 6.8.1: Display Example of GIS/DB Utilization .................................................... 6-15 Figure 6.8.2: Screen Shot (Example): Population/water Source Type of the
Target Town ................................................................................................ 6-16 Figure 6.8.3: Screen Shot (Example): Concentration of
Fluoride/Yield/Groundwater Contour ......................................................... 6-16
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Figure 6.8.4: Screen Shot (Example): Water Tariff/Well Construction Year of the Target Town .......................................................................................... 6-16
Figure 6.8.5: Screen Shot (Example): Sufficiency Rate of Existing Water Supply Facilities to Water Demand with Target Town Location ............................ 6-17
Figure 6.8.6: Screen Shot (Example): Water Sampling Point with Contamination of Bacteria ................................................................................................... 6-17
Figure 7.2.1: Groundwater Basin of the Modeling Target Area (SRTM Data). ................ 7-1 Figure 7.2.2: Boundary Specification of Modeling Target Area ........................................ 7-2 Figure 7.3.1: Initial Model Layer Specification for Row 32 .............................................. 7-3 Figure 7.3.2 Initial Model Layer Specification for Column 73 .......................................... 7-3 Figure 7.3.3: Location of Rivers and Lakes in the Study Area .......................................... 7-4 Figure 7.3.4: Boundary Specification of Initial Model ...................................................... 7-4 Figure 7.3.5: Distribution of Water Level Observation Wells. .......................................... 7-5 Figure 7.3.6: Relation of Groundwater Level and Elevation ............................................. 7-6 Figure 7.3.7: Initial Water Level Contour. ......................................................................... 7-6 Figure 7.3.8: Initial Hydraulic Conductivity Distribution .................................................. 7-8 Figure 7.3.9: Groundwater Recharge Package ................................................................... 7-9 Figure 7.3.10: Comparison of Wells Distribution (Initial and Modified) ........................ 7-11 Figure 7.3.11: Well Package (First layer of the Initial and Modified Model) .................. 7-12 Figure 7.3.12 Well Package (Second layer of the Initial and Modified Model) .............. 7-12 Figure 7.3.13: Well Package (Second layer of the Initial and Modified Model) ............. 7-13 Figure 7.3.14: Comparison of Initial Grid Size and Modified Grid Size ......................... 7-14 Figure 7.3.15: Comparison of Initial and Modified Row Specification. .......................... 7-14 Figure 7.3.16: Comparison of Initial and Modified Column Specification...................... 7-15 Figure 7.3.17: Comparison of Initial and New Boundary Specification .......................... 7-16 Figure 7.4.1: Number of Dry Cells Found in the First Calculation by Modified
Model .......................................................................................................... 7-16 Figure 7.4.2: Comparison of Initial Water Level and Calculated Model ......................... 7-17 Figure 8.2.1: Related chart of Ethiopian Water Sector Policies and Plan .......................... 8-3 Figure 8.3.1: Major Towns in Oromia Region ................................................................... 8-7 Figure 8.3.2: Local Administrative Chart for Regional Government, Zone,
Woreda, Town and Kebele ............................................................................ 8-9 Figure 8.3.3: Organization Structure of the Relevant Department in MoWIE ................ 8-10 Figure 8.3.4: Organization Structure of the Relevant Departments in OWMEB ............. 8-11 Figure 8.3.5: Road Condition (1) toward the Target Towns ............................................ 8-15 Figure 8.3.6: Road Condition (2) toward the Target Towns ............................................ 8-15 Figure 8.3.7: Location and Access Road for 30 Target Towns in Oromia Region .......... 8-16 Figure 8.3.8: Adama Wind Farm and Awash Melkasa Hydropower Plant ...................... 8-17 Figure 8.4.1: Composition of Ethnic Group and Religion for Household’s
Survey in Target Towns .............................................................................. 8-46 Figure 8.4.2: Households Revenues of Every 30 Target Town........................................ 8-47 Figure 8.4.3: Composition of Occupation for Household Survey in 30 Target
Towns .......................................................................................................... 8-48 Figure 8.4.4: Consciousness for Treating Water and Recent Experience of
Diarrhea ....................................................................................................... 8-50 Figure 8.4.5: Photos of the Interview Survey of Sanitation Conditions ........................... 8-51 Figure 8.4.6: Person in Charge of Water Fetching in Family in the Household
Survey .......................................................................................................... 8-53 Figure 8.4.7: School Attendance Ratio of Age 7-14 of 30 Target Towns ........................ 8-53 Figure 8.4.8: Taking Measures for Protection against Soil Erosion in Guba
Qoricha Woreda .......................................................................................... 8-54
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Figure 8.4.9: Location for Wonji-Shoa Sugar Factory ..................................................... 8-55 Figure 8.4.10: Main Intake for Wonji-shoa Sugar Factory .............................................. 8-55 Figure 8.4.11: Location of Metehara Sugar Factory ........................................................ 8-58 Figure 8.4.12: River Water Intake Gate in Abadir Farm Area in Metehara Sugar
Factory ......................................................................................................... 8-58 Figure 8.4.13: Location of Nura Hera Farm ..................................................................... 8-60 Figure 9.2.1: Location Map of Target Towns .................................................................... 9-5 Figure 9.5.1: Organization Chart of OWMEB ................................................................. 9-55 Figure 9.5.2: Organization Chart of ZWMEO ................................................................. 9-56 Figure 9.5.3: Organization Chart of WWMEO ................................................................ 9-57 Figure 9.5.4: Support Structure for Maintenance Management ....................................... 9-62 Figure 10.3.1: General scheme on water supply system with water tank on the
ground .......................................................................................................... 10-3 Figure 10.3.2: General scheme on water supply system with elevated water tank .......... 10-3 Figure 10.5.1: Location of the study area ......................................................................... 10-6 Figure 10.5.2: Isohyetal Map of the Middle Awash River Basin ..................................... 10-7 Figure 10.5.3: Distribution of African Rift Valley ........................................................... 10-8 Figure 10.5.4: Small incinerators at HCs, out of use (Areda town) ................................. 10-9 Figure 10.7.1: Organogram of OLEPB and agencies concerned ................................... 10-13 Figure 10.11.1: Water retailer in Aneno town ................................................................ 10-19 Figure 10.11.2: Road condition ...................................................................................... 10-20 Figure 11.2.1: Location Map of Lake Beseka .................................................................. 11-1 Figure 11.2.2: Current Situation of Lake Beseka ............................................................. 11-2 Figure 11.2.3: Long-term Annual Water Balance of Beseka Lake and its
Watershed (Ayalew, 2009) .......................................................................... 11-2 Figure 11.2.4: Water Balance of Beseka Lake (WWDSE, 2011) .................................... 11-3 Figure 11.2.5: Time Series of Water Level of Lake Beseka (1977–2009) ....................... 11-4 Figure 11.2.6: Time Series of Water Level of Lake Beseka (1912–2009) ....................... 11-4 Figure 11.2.7: Area-Elevation and Volume-Elevation Curves of Lake Beseka
based on 1:5,000 Topographic Map ............................................................ 11-5 Figure 11.2.8: Time Series of Water Surface Area of Lake Beseka (1912–2009) ........... 11-5 Figure 11.2.9: Time Series of Stored Water Volume in Lake Beseka
(1912–2009) ................................................................................................ 11-5 Figure 11.2.10: Changes in Water Volume in Lake Beseka ............................................ 11-6 Figure 11.2.11: Annual Rainfall at Metehara versus Lake Volume Change
(1977–1998) ................................................................................................ 11-6 Figure 11.2.12: Long-term Annual Rainfall at the Sugar Estate in Metehara Area ......... 11-7 Figure 11.2.13: Estimated Outflow from Lake Beseka .................................................... 11-8 Figure 11.2.14: Irrigation Projects in and around the Lake Beseka Watershed ............... 11-9 Figure 11.3.1: Elevation Map around Lake Beseka ....................................................... 11-13 Figure 11.3.2: Topographic Classification Map around Lake Beseka
(background: shaded relief map created from ASTER DEM data) .......... 11-14 Figure 11.3.3: NW-SE Topographic Section around Lake Beseka (A-A’) .................... 11-15 Figure 11.3.4: E-W Topographic Section around Lake Beseka (B-B’) ......................... 11-15 Figure 11.3.5: N-S Topographic Section around Lake Beseka (C-C’) .......................... 11-16 Figure 11.3.6: Index map of aerial photos used for the topographical analysis ............. 11-16 Figure 11.3.7: Paleo-channel flowing into the southern part of Lake Beseka ............... 11-17 Figure 11.3.8: Geological Map around Lake Beseka ..................................................... 11-18 Figure 11.3.9: Geological section around Lake Beseka ................................................. 11-19 Figure 11.3.10: Outcrop photos of Birenti-Hada rhyolites ............................................. 11-20 Figure 11.3.11: Outcrop photos of the older ignimbrite ................................................. 11-21
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Figure 11.3.12: Outcrop photos of the Nura Hira basalts ............................................... 11-22 Figure 11.3.13: Outcrop photo of Dino ignimbrite ........................................................ 11-22 Figure 11.3.14: Outcrop photos of Sobebor volcanic sand beds .................................... 11-23 Figure 11.3.15: Outcrop photos of the Pleistocene basalts ............................................ 11-25 Figure 11.3.16: Outcrop photo of Kone ignimbrite ........................................................ 11-26 Figure 11.3.17: Outcrop photos of the Fentale volcanic rocks ....................................... 11-27 Figure 11.3.18: Outcrop photos of the Fentale ignimbrite ............................................. 11-28 Figure 11.3.19: Outcrop photos of the blisters of the Fentale ignimbrite ...................... 11-29 Figure 11.3.20: Outcrop photos of the recent basalts ..................................................... 11-30 Figure 11.3.21: Photos of alluvial plains and deposits ................................................... 11-30 Figure 11.3.22: Location of existing wells and observation wells constructed by
this project and profile lines around Lake Beseka .................................... 11-32 Figure 11.3.23: Borehole log profile A-A’ section ........................................................ 11-33 Figure 11.3.24: Borehole log profile B-B’ section ......................................................... 11-34 Figure 11.3.25: Borehole log profile C-C’ section ......................................................... 11-35 Figure 11.3.26: Borehole log profile D-D’ section ........................................................ 11-36 Figure 11.3.27: Borehole log profile E-E’ section ......................................................... 11-37 Figure 11.3.28: Borehole log profile F-F’ section .......................................................... 11-38 Figure 11.3.29: Outcrop photos of faults distributed in the detailed study area............. 11-40 Figure 11.4.1: Geological Map, Existing Wells and JICA Wells around Lake
Beseka ....................................................................................................... 11-42 Figure 11.4.2: Columnar Section of JICA Well (AW BH-3) and Geological
Correlation ................................................................................................. 11-43 Figure 11.4.3: Columnar Section of JICA Well (AW BH-4N) and Geological
Correlation ................................................................................................. 11-43 Figure 11.4.4: Columnar Section of JICA Well (AW BH-5) and Geological
Correlation ................................................................................................. 11-44 Figure 11.4.5: Groundwater Level Contour Map around Lake Beseka (Less than
100 m depth of Existing Wells) ................................................................. 11-46 Figure 11.4.6: Groundwater Level Contour Map around Lake Beseka (More than
100 m depth of Existing Wells) ................................................................. 11-46 Figure 11.4.7: Well Depth and Fluoride Concentration around Lake Beseka ............... 11-48 Figure 11.4.8: Hydrogeological Map around Lake Beseka ............................................ 11-49 Figure 11.4.9: Hydrogeological Section around Lake Beseka ....................................... 11-50 Figure 11.5.1: Result of Water Temperature Study around Lake Beseka ...................... 11-51 Figure 11.5.2: The Analysis Flow of Surface Temperature using Landsat Data ........... 11-53 Figure 11.5.3: Changes of Surface Temperature in Lake Beseka .................................. 11-53 Figure 11.5.4: Location of Lake Beseka, Lake Koka and the sampling point on
the Awash .................................................................................................. 11-54 Figure 11.5.5: Changes of Surface Temperatures in Lake Koka.................................... 11-55 Figure 11.5.6: Comparison of Surface Temperatures between Lake Beseka and
Lake Koka ................................................................................................. 11-55 Figure 11.5.7: Surface Temperature Distribution of Lake Beseka ................................. 11-56 Figure 11.5.8: Surface Temperature of the Awash around Abadir Farm and Lake
Beseka ....................................................................................................... 11-57 Figure 11.5.9: Location Map of Water Quality Testing Points around Lake
Beseka ....................................................................................................... 11-60 Figure 11.5.10: Trilinear Diagram around Lake Beseka ................................................ 11-62 Figure 11.5.11: Hexadiagram at Sampling Points around Lake Beseka ........................ 11-63 Figure 11.5.12: Hexadiagram of Main Sampling Points at West of Lake Beseka ......... 11-64
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Figure 11.5.13: Hexadiagram of Main Sampling Points at South West of Lake Beseka ....................................................................................................... 11-65
Figure 11.5.14: Hexadiagram of Main Sampling Points at South of Lake Beseka ........ 11-66 Figure 11.5.15: Delta Diagram of Stable Isotope around Lake Beseka ......................... 11-70 Figure 11.5.16: Lake Water Level and Timing of Operation of Irrigation Projects ....... 11-72 Figure 11.5.17: Irrigation Water Losses ......................................................................... 11-73 Figure 11.5.18: Irrigation Efficiency Calculation Used in this Project .......................... 11-74 Figure 11.5.19: Growth Stages of Sugarcane ................................................................. 11-75 Figure 11.5.20: Water Balance in Isolated Lake Catchment .......................................... 11-78 Figure 11.5.21: Mean Annual Water Balance in the Lake Beseka (ELSA 33.4
km2) ........................................................................................................... 11-79 Figure 11.5.22: Mean Annual Water Balance in the Lake Beseka with Outflow
“X” (ELSA 4 km2) ................................................................................. 11-80 Figure 11.5.23: Mean Annual Water Balance in the Lake Beseka with Loss “Y”
(ELSA 4 km2) ......................................................................................... 11-81 Figure 11.5.24: Observed and Simulated Historical Changes of the Lake Water
Level .......................................................................................................... 11-81 Figure 11.5.25: Observed and Simulated Historical Changes of the Lake Surface
Area ........................................................................................................... 11-82 Figure 11.5.26: Mean Annual Water Balance in the Lake Beseka with 35 MCM
Return Flow ............................................................................................... 11-83 Figure 11.5.27: Mean Annual Water Balance in the Lake Beseka with 46.2
MCM Return Flow .................................................................................... 11-84 Figure 11.5.28: Mean Annual Water Balance in the Lake Beseka with 102 MCM
Return Flow ............................................................................................... 11-85 Figure 11.5.29: Simulated Time Series of the Lake Water Level with Irrigation
Return Flow ............................................................................................... 11-86 Figure 11.5.30: Simulated Time Series of the Lake Surface Area with Irrigation
Return Flow ............................................................................................... 11-86 Figure 11.5.31: Mean Annual Water Balance in the Lake Beseka with 35 MCM
Return Flow (without loss “Y”) ................................................................ 11-87 Figure 11.5.32: Mean Annual Water Balance in the Lake Beseka with 102 MCM
Return Flow (without loss “Y”) ................................................................ 11-88 Figure 11.5.33: Annual Additional Inflow to the Lake required for Explanation
of Actual Lake Rise ................................................................................... 11-89 Figure 11.5.34: Annual Groundwater Inflow to the Lake estimated in WWDSE
(2011) ........................................................................................................ 11-90 Figure 11.6.1: Location of Irrigation Farms around Lake Beseka ................................. 11-91 Figure 11.6.2: Results of Irrigation Return Flow and Water Level (50% of
Irrigation Return Flow) ............................................................................. 11-93 Figure 11.6.3: Result of Irrigation Return Flow and Water Level (Equal to the
Irrigation Return Flow) ............................................................................. 11-94 Figure 11.6.4: Result of Irrigation Return Flow and Water Level (Double of
Irrigation Return Flow) ............................................................................. 11-95 Figure 11.6.5: Results of Water Level of the Lake and River Inflow (Same as
Return Flow) ............................................................................................. 11-96 Figure 11.6.6: Model Estimation of Groundwater Fluctuation in Abadir Farm
(Irrigation Return Flow) ............................................................................ 11-97 Figure 11.6.7: Model Estimation of Groundwater Fluctuation of Abadir Farm
(by the Return Flow from the River) ......................................................... 11-98
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Figure 11.6.8: Comparison of the Water Level at Lake Beseka and Irrigation Return Flow ............................................................................................... 11-99
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Abbreviations AAU Addis Ababa University AGRAP Alidge Groundwater Resources Assessment Project AIDS Acquired Immune Deficiency Syndrome ALOS Advanced Land Observing Satellite ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer ASTER-GDEM ASTER-Global Digital Elevation Model BFI Base Flow Index CAD Computer Aided Design (System) CDE Center for Development and Environment, Ministry of Agriculture CFC Chloride Fluoride Carbon CREC China Railway Engineering Corporation CSA Central Statistical Agency CSE The Conservation Strategy of Ethiopia C/P Counterpart (organization or personnel) DB Datebase DCI Ductile Cast Iron DEM Digital Elevation Model DF/R Draft Final Report DTH Down-the-hole Hammer DWL Dynamic Water Level EA Environmental Assessment EC Electric Conductivity EEPCO Ethiopia Electric Power Corporation EGRAP Ethiopian Groundwater Resources Assessment Program EIA Environmental Impact Assessment EIGS Ethiopian Institute of Geological Survey, now renamed as Geological Survey of
Ethiopia (GSE) EL Elevation ELC Elc electroconsult milano and Geotermica italiana pisa, Italia (an Italian
Consultant) ELSA Equilibrium Lake Surface Area EMA Ethiopia Mapping Agency ENGDA Ethiopian National Groundwater Database ENGWIS Ethiopian National Groundwater Information System EPA Environmental Protection Agency, now renamed as Ministry of Environment
and Forest (MEF) EPC Environmental Protection Council ERA Ethiopian Road Authority ERC Ethiopian Railway Corporation ESA Ethiopian Standard Agency ESIA Environmental and Social Impact Assessment ET Evapotranspiration EWCA Ethiopian Wildlife Conservation Authority EWTEC Ethiopia Water Technology Center, now renamed as Ethiopia Water
Technology Institute (EWTI) EWTI Ethiopia Water Technology Institute, formerly known as Ethiopia Water
Technology Center (EWTEC) F/R Final Report FAO Food and Agriculture Organization of the United Nations FAO-AGLW FAO Water Resource, Development and Management Services FDM Finite Difference Method FEM Finite Element Method GD Groundwater Directorate (of MoWIE)
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GDP Gross Domestic Product GHB General Head Boundary GIS Geographical Information System GL Ground Level GNI Gross National Income GPS Global Positioning System GSE Geological Survey of Ethiopia GSP Galvanized Steel Pipe GTP Growth and Transformation Plan GWR Groundwater Recharge HIV Human Immunodeficiency Virus IAEA International Atomic Energy Agency IC/R Inception Report IEE Initial Environmental Examination IMF International Monetary Fund INGEIS Instituto de Geocronología y Geología Isotópica (Institute of Geochronology
and Geology, Argentine) ISO International Standard Organization ISODATA The Iterative Self-Organizing Data Analysis Technique IT/R Interim Report ITCZ Inter-tropical Convergence Zone JICA Japan International Cooperation Agency LEL Local Evaporation Line LMWL Local Meteoric Water Line M&E Monitoring and Evaluation M/M Minutes of Meeting MCM Million Cubic Meter MDGs Millennium Development Goals MEF Ministry of Environment and Forest, formerly known as Environmental
Protection Agency (EPA) MER Main Ethiopian Rift MOA Ministry of Agriculture MoWR Ministry of Water Resources, now renamed as Ministry of Water, Irrigation and
Electricity (MoWIE) MoWE Ministry of Water and Energy, now renamed as Ministry of Water, Irrigation
and Electricity (MoWIE) MoWIE Ministry of Water, Irrigation and Electricity, formerly known as Ministry of
Water, Irrigation and Energy(MoWIE), Ministry of Water and Energy (MoWE) or Ministry of Water Resources (MoWR)
MSE Metehara Sugar Estate MWL Meteoric Water Line NASA National Aeronautics and Space Administration, USA NGI National Groundwater Institute NGO Non-Governmental Organization NMA National Meteorology Agency OLEPB Oromia Land and Environmental Protection Bureau ORP Oxidation and Reduction Potential O(R)WMEB Oromia (Regional) Water, Material and Energy Development Bureau OWNP One WASH National Program OWWDSE Oromia Water Works Design and Supervision Enterprise P/R Progress Report PA Preliminary (Environmental) Assessment PASDEP Plan for Accelerated and Sustained Development to End Poverty PC Personal Computer
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PPP Purchasing Power Parity PRSP Poverty Reduction Strategy Paper PVC Polyvinyl Chloride R/D Record of Discussions REA Regional Environmental Agencies RESTEC Remote Sensing Technology Center of Japan RVLB Rift Valley Lakes Basin SC Steering Committee SCM Steering Committee Member or Steering Committee Meeting SDPRP Sustainable Development and Poverty Reduction Program SEA Strategic Environmental Assessment SFGS Streamflow Gauging Station SP Spontaneous potential SPOT Satellite Pour l'Observation de la Terre (French Satellite for Earth Observation)SRTM Shuttle Radar Topography Mission SS Suspended Solids TDS Total Dissolved Solids TEM Transient (or Time-domain) Electromagnetic Method TIR Thermal Infrared TM Thematic Mapper TOR Terms of Reference TU Tritium Unit TWSSO Town Water Supply Service Office TWSSSE Town Water Supply and Sewerage Service Enterprise UAP Universal Access Program UNEP United Nations Environment Programme UNESCO United Nations Educational, Scientific and Cultural Organization UNICEF United Nations Children’s Fund uPVC Unplasticized Polyvinyl Chloride USBR United States Bureau of Reclamation USGS United States Geological Survey UTM Universal Transversal Mercator VES Vertical Electrical Sounding VIP Ventilation Improved Pit WASH Water Supply, Sanitation and Hygiene Program WB World Bank WC Water Committee WFB Wonji Fault Belt WHO World Health Organization WSDP Water Sector Development Program WSSM Water Supply and Sanitation Master Plan WWDSE Water Works Design and Supervision Enterprise WWMEO Woreda Water, Mineral and Energy Office ZWMEO Zonal Water, Mineral and Energy Office
Project Photos (1/5)
Discussion of IC/R
The discussions held on 5 Nov. 2013 were participated by Ministry of Water, Irrigation and Electricity and Geological Survey of Ethiopia. The M/M was exchanged on 11 Nov
Project Introduction
Introducing the outline of the Project to the stakeholder when purchasing the hydrological information.
Site Visit (1)
Discussion between counterparts and experts regarding the construction period of the railway during the site visit to Lake Beseka.
Site Visit (2)
Currently, the water is being discharged to Awash River by a canal at the eastside of the lake as a countermeasure for water level rise
Geophysical Survey (1)
The observation drilling sites were selected based on the resistivity information (200 m depth) of underground obtained from the geophysical survey (VES).
Geophysical Survey (2)
The observation drilling sites were selected based on the resistivity information (400 m depth) of underground obtained from the geophysical survey (TEM).
Project Photos (2/5)
Geological Survey (1) The C/P from MoWIE has accompanied the experts in the geological survey for at least 3 months to finalize the geological map.
Geological Survey (2) Megacha highly welded tuff that overlies Bofa Basalt to the west of Bofa.
Socio-Economic Survey Focus Group discussions regarding water use status at Kinteri Town of Oromia Region.
Water Usage Inventory Survey (1) Survey of existing water facilities at Geldiya Town in Oromia Region.
Water Usage Inventory Survey (2)Situation at the public water tap of Areda Town of Oromia Region. Twenty litres of water cost around 2 Japanese Yen.
Sampling for IAEA Analysis The tubing method of sampling Helium gas using copper pipe was instructed in order to facilitate IAEA stable isotope analysis.
Project Photos (3/5)
First C/P Meeting Discussions on P/R1 held on 24 April 2014, with participants from the Ministry of Water, Irrigation and Electricity and Oromia Region. The M/M was exchanged later.
Site Visit by JICA (1) Outcrops of rhyolite observed along the Arba River, a tributary of the Awash River. Discussions about geology were had with the C/Ps.
Site Visit by JICA (2) The topographical and geological field survey was carried out in April 2014 at the Study area with Dr. Suzuki, Professor of Okayama University in Japan.
Wonji Sugar Plantation This large-scale national sugar plantation is located about 10 km south of Adama Town. The photo shows an interview in regard to the general conditions of the plantation.
Metehara Sugar PlantationThis large-scale national sugar plantation is located about 5 km south of Metehara Town. Its area is more than 10,000 ha. The photo shows a well within the plantation.
Observation Well Drilling (1) Clay balls made of mixed bentonite and straw are thrown into well AWBH-3 to prevent circulation loses and wall collapses between the surface and a depth of 30 m.
Project Photos (4/5)
Observation Well Drilling (2) Well cleaning at AWBH-11: High-pressured air is sent into the well to discharge the remaining mud after the completion of the well.
Observation Well Drilling (3) Pumping test at AWBH-1: The volume of pumped groundwater is measured by reading the water level (cm) which overflows the triangular notch tank.
Sampling for Water Quality Test (1)Water for quality testing was sampled in existing wells, springs, river water, lake water, and so on. The water quality was classified by analysis. The photo shows the sampling of a deep well in East Shewa
Sampling for Water Quality Test (2) The photo shows the sampling of spring water at the west side of Lake Beseka. The results of analysis of the spring flowing into Lake Besaka are different from that of other springs.
Sampling for Water Quality Test (3)
Water quality sampling was undertaken in the irrigation farm. The result shows the similar characteristic as south shore of Lake Beseka with high HCO3 which caused by the vegetation.
Discussion of Progress Report 2
Discussion of P/R2 was held on 24th July 2014 attended by the C/P from Ministry of Water, Irrigation and Energy and Oromia Region. The M/M was exchanged later.
Project Photos (5/5)
GIS Workshop
GIS Workshop was held on 30th January 2015 at MoWIE. The theme was about the outline of GIS database for groundwater resources assessment.
Tone Spring
Tone spring is located at the southwest of Lake Beseka. The discharge volume could not be measured since it is submerged though the spring can be observed.
Environmental and Social Consideration Situation during an interview at Department of Education at Woreda Office in Mojo. The information/data related to water fetching situation enrollment rate was collected.
Discussion of Interim Report Discussion of IT/R was held on 11th July 2015. The contents have been discussed with the Deputy Minister of MoWIE. The M/M was exchanged later.
Technology Transfer Seminar The Technology Transfer Seminar was held on 27th October 2015. The presentation includes the output, tasks and recommendations. The seminar was attended by C/Ps (MoWIE, EWTI, GSE, OWMEB and AAU) and NGOs.
Discussion of Draft Final Report Discussion of DF/R was held on 27th October 2015 and the utilization method of this reports after the Project period have been discussed. The M/M was exchanged later.
Chapter 1
Meteorology and Hydrology
The Project for Groundwater Resources Assessment JICA in the Middle Awash River Basin, Final Report (Supporting Report) KOKUSAI KOGYO CO., LTD.
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1 Meteorology and Hydrology
1.1 Review of meteorology data
1.1.1 Meteorological observation network and items
Meteorological stations in Ethiopia, which are managed by the National Meteorological Agency (hereafter referred to as “NMA”), are categorized into the following classes:
Principal Meteorological Station: For observation of 1) daily rainfall, 2) maximum temperature, 3) minimum temperature, 4) dry bulb temperature, 5) wet bulb temperature, 6) relative humidity, 7) sunshine duration hours, 8) wind run, 9) wind speed/direction, 10) cloud amount, 11) soil temperature, 12) pan evaporation, and 13) Piche evaporation.
Synoptic Meteorological Station: For observation of 14) grass minimum temperature, 15) station level pressure, 16) sea level pressure, 17) weather (present/past), 18) height of low cloud, and 19) horizontal visibility, in addition to the above-mentioned 13 items observed at Principal stations.
Ordinary Meteorological Station: For observation of 1) daily rainfall, 2) maximum temperature, and 3) minimum temperature.
Precipitation Meteorological Station: For observation of daily rainfall.
Location map of the NMA’s meteorological stations in and around the Middle Awash River Basin is shown in Figure 1.1.1.
Source: NMA
Figure 1.1.1: Meteorological Stations in and around the Middle Awash River Basin
The Project for Groundwater Resources Assessment JICA in the Middle Awash River Basin, Final Report (Supporting Report) KOKUSAI KOGYO CO., LTD.
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Number of meteorological stations in the Middle Awash River Basin are tabulated by class (Table 1.1.1).
Table 1.1.1: Number of Meteorological Stations in the Middle Awash River Basin
Class Number of Stations Remarks Principal Met. Station 8 Addis Ababa Obs., BES, Melkasa
(IAR), Nazret, Abomsa, Nuraera, Shola Gebeya, Awash Arba
Synoptic Met. Station 3 Addis Ababa Bole, Debre Zeit (AF), Metehara
Ordinary Met. Station 30 Precipitation Met. Station 33
Total 74 Source: the Project Team, Data: Location data of NMA’s observatories Meteorological data collected from NMA were analyzed as described in the following subsections.
1.1.2 Rainfall
a. Data availability
Daily rainfall data of 62 years (1951–2012) from the following 20 observatories were purchased from NMA. The stations were selected such that the target basin is equally covered. Figure 1.1.2 shows the data availability of each rainfall station.
The Project for Groundwater Resources Assessment JICA in the Middle Awash River Basin, Final Report (Supporting Report) KOKUSAI KOGYO CO., LTD.
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Easting Northing(m) (m) 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
Abomsa 589,895 935,898 1,630 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 79% 100% 100% 67% 17% 1% 100% 100% 67% 17% 8% 0% 0% 0%
Addis Ababa Obs 472,521 994,771 2,386 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 0%
Aleltu 516,300 1,021,400 2,648 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Ambo Agriculture 375,409 991,269 2,068 100% 100% 100% 0% 8% 0% 0% 0% 0% 0% 59% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 75% 28% 34% 1% 4% 7% 4% 8%
Arbuchulele 415,000 940,000 2,434 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Asgori 426,480 971,728 2,072 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 25% 66% 67% 100% 75% 0% 8% 84% 43% 0% 0% 0% 0% 0% 0% 8% 0% 0% 16%
Awash Arba 627,084 1,008,145 780 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Debre Zeit (AF) 494,500 965,283 1,900 8% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 8% 8% 8% 0% 0% 8% 0% 0% 0% 0% 0% 0% 0% 50% 1% 1% 0% 2%
Gelemso 666,808 974,833 1,739 100% 100% 25% 100% 50% 58% 0% 8% 50% 0% 0% 0% 8% 100% 2% 0% 0% 0% 0% 0% 0% 0% 83% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 6% 0% 1% 0% 1%
Hombole 474,310 924,757 1,743 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 47% 100% 0% 0% 100% 100% 0% 1% 0% 0% 100% 0% 8% 0% 0% 0% 0% 0% 0% 0% 0% 8% 50% 16% 0% 0% 0% 17%
Kulumsa 514,689 898,959 2,211 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 8% 0% 0% 0% 0% 0% 0% 8% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Mieso Mission 692,257 1,021,027 1,332 100% 75% 42% 100% 41% 50% 83% 17% 50% 100% 67% 0% 100% 100% 0% 16% 34% 8% 58% 100% 100% 58% 1% 32% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Melka Jilo 568,000 983,000 1,135 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Melka Were 630,763 1,034,784 740 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 17% 100% 100% 100% 100% 53% 65% 0% 59% 33% 0% 0% 8% 0% 1% 83% 33%
Melkasa (IAR) 534,862 928,448 1,540 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Metehara (NMSA) 598,964 980,142 944 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 78% 0% 0% 0% 0% 0% 0%
Nazret 531,181 945,027 1,622 100% 100% 75% 25% 59% 58% 42% 25% 8% 16% 100% 100% 100% 94% 0% 25% 42% 59% 33% 0% 33% 0% 0% 0% 17% 16% 0% 8% 17% 68% 8% 3% 2% 0% 8% 1% 0% 0% 0% 0%
Shola Gebeya 544,129 1,017,818 2,500 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Woliso Giyon 388,112 945,164 2,058 100% 76% 33% 0% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 33% 0% 8% 0% 0% 0% 0% 0%
Debre Berhan 554,860 1,064,816 2,750 100% 100% 100% 33% 42% 50% 14% 10% 2% 25% 100% 100% 100% 92% 66% 55% 0% 0% 17% 24% 76% 16% 67% 42% 0% 25% 33% 0% 8% 6% 9% 1% 8% 0% 0% 0% 0% 2% 0% 0%
ContinuedEasting Northing
(m) (m) 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12Abomsa 589,895 935,898 1,630 0% 3% 1% 0% 0% 0% 0% 0% 0% 2% 1% 17% 0% 1% 8% 0% 1% 0% 0% 0% 0% 17%
Addis Ababa Obs 472,521 994,771 2,386 2% 0% 0% 0% 1% 0% 0% 0% 1% 0% 0% 0% 0% 0% 8% 1% 0% 0% 0% 0% 0% 0%
Aleltu 516,300 1,021,400 2,648 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 75% 92%
Ambo Agriculture 375,409 991,269 2,068 75% 100% 0% 100% 100% 100% 5% 59% 0% 0% 0% 3% 0% 1% 0% 1% 0% 0% 0% 0% 9% 1%
Arbuchulele 415,000 940,000 2,434 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 8% 8% 0% 0% 100% 100% 100% 100%
Asgori 426,480 971,728 2,072 0% 0% 0% 0% 0% 0% 0% 0% 0% 8% 0% 0% 0% 0% 0% 50% 83% 8% 67% 34% 92% 25%
Awash Arba 627,084 1,008,145 780 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 25% 0% 0% 8% 92%
Debre Zeit (AF) 494,500 965,283 1,900 100% 100% 100% 9% 1% 0% 0% 0% 0% 1% 0% 0% 0% 16% 0% 0% 17% 0% 0% 0% 67% 27%
Gelemso 666,808 974,833 1,739 67% 100% 100% 100% 100% 100% 100% 100% 100% 50% 50% 1% 0% 0% 8% 1% 0% 0% 0% 0% 1% 43%
Hombole 474,310 924,757 1,743 0% 8% 71% 100% 100% 100% 55% 0% 1% 50% 0% 25% 0% 8% 58% 17% 0% 0% 83% 25% 0% 50%
Kulumsa 514,689 898,959 2,211 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 0%
Mieso Mission 692,257 1,021,027 1,332 19% 2% 1% 0% 0% 20% 1% 0% 1% 0% 0% 0% 1% 0% 0% 0% 100% 100% 100% 100% 100% 100%
Melka Jilo 568,000 983,000 1,135 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 84% 58% 59% 84% 50% 67%
Melka Were 630,763 1,034,784 740 17% 100% 100% 100% 100% 100% 100% 58% 25% 0% 67% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Melkasa (IAR) 534,862 928,448 1,540 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Metehara (NMSA) 598,964 980,142 944 0% 0% 0% 0% 0% 1% 2% 0% 0% 0% 0% 0% 0% 0% 0% 0% 3% 0% 0% 0% 1% 3%
Nazret 531,181 945,027 1,622 10% 2% 1% 0% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 0% 0% 0% 17% 0% 0% 1%
Shola Gebeya 544,129 1,017,818 2,500 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 0% 0% 8% 8% 0% 0%
Woliso Giyon 388,112 945,164 2,058 5% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 0% 0% 0% 0% 0% 0% 0% 1% 2% 1% 0%
Debre Berhan 554,860 1,064,816 2,750 3% 0% 1% 8% 8% 0% 17% 0% 0% 0% 0% 0% 0% 0% 0% 8% 0% 0% 0% 0% 0% 0%
Rate of Missing Data: : more than 90% : 50% to 90% : 25% to 50% : less than 25% : Complete data (0%)
Station Elevation(m amsl)
Station Elevation(m amsl)
Year
Year
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.2: List of Rainfall Stations with Available Data
Daily rainfall data are available from 1951 at Addis Ababa and Debre Zeit (AF) observatories, while data for only several years are available at Aleltu, Arbuchulele, Awash Arba, and Shola Gebeya observatories.
b. Long-term tendency of annual point rainfall
The historical trends of annual rainfall at Addis Ababa, Debre Zeit (AF), and Kulumsa are analyzed as shown in Figure 1.1.3–Figure 1.1.5, respectively.
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y = 2.1245x - 3026.2
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1,000
1,200
1,400
1,600
1,800
1950 1960 1970 1980 1990 2000 2010
Rain
fall
(mm
)
Year
Annual Rainfall5-yr Moving AverageTrend Line
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.3: Historical Trend of Annual Rainfall at Addis Ababa (1951–2011)
y = 1.5604x - 2178.9
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
1950 1960 1970 1980 1990 2000 2010
Rain
fall
(mm
)
Year
Annual Rainfall5-yr Moving AverageTrend Line
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.4: Historical Trend of Annual Rainfall at Debre Zeit (1952–2011)
y = -0.2238x + 1279.2
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
1950 1960 1970 1980 1990 2000 2010
Rain
fall
(mm
)
Year
Annual Rainfall5-yr Moving AverageTrend Line
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.5: Historical Trend of Annual Rainfall at Kulumsa (1972–2012)
The graphs show the annual rainfall for the years without missing data together with 5-years moving average and linear trend line for each observatory. Slight upward trend is observed at Addis Ababa and Debre Zeit, while a downward trend is observed at Kulumsa. Therefore, no significant tendency in annual rainfall in the Middle Awash River Basin is indicated.
c. Spatial rainfall distribution
Isohyetal map of the Middle Awash River Basin is generated on the basis of the collected rainfall data. The map is generated in the following procedure:
i) Annual rainfall at each rainfall observatory is calculated.
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ii) The calculated annual point rainfall are marked on the map at the location of each observatory.
iii) Lines that show equal amount of annual rainfall are delineated manually referring to the point rainfall.
The generated isohyetal map is shown in Figure 1.1.6.
Source: the Project Team, Data: the NMA’s daily rainfall data
Figure 1.1.6: Isohyetal Map of the Middle Awash River Basin
The annual rainfall is larger in the northwestern (i.e., upstream) part of the basin. The areas with low annual rainfall are found in the downstream. Annual rainfall in the western and northwestern areas reaches more than 1,000 mm. The annual rainfall in the middle reaches of the Middle Awash around Lake Koka is 800–900 mm. Rainfall of 500 mm or less is observed in the downstream of the Middle Awash from Metehara.
According to Figure 1.1.6, prominent peaks of monthly rainfall can be seen in July and August. Small rainfall peaks are found in March and April in many observatories. The Middle Awash River Basin is located in the climate area characterized by three distinct seasons: Bega (dry season; October–January), Bleg (small rainy season; February–May), and Kiremt (main rainy season; June–September). The rainfall in the area is largely influenced by the position of the Intertropical Convergence Zone (hereafter referred to as “ITCZ”), which is the zone of atmospheric depression formed near equator and shifts north and south in accordance with apparent position of the sun with respect to the earth. The Middle Awash River Basin area experiences the main rainy season when the ITCZ is at its northern-most position around northern Ethiopia to Arabian Peninsula (see Figure 1.1.7).
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[January] [July]
Source: Grid Africa by United Nations Environment Programme (UNEP)
Figure 1.1.7: Seasonal Drifting of the ITCZ in Africa
The relationship between elevation and annual rainfall at the observatories is plotted as in Figure 1.1.8.
R² = 0.5816
0
500
1,000
1,500
2,000
2,500
3,000
0 200 400 600 800 1,000 1,200 1,400
Elev
atio
n (M
SL)
Rainfall [mm]
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.8: Relationship between Elevation and Annual Rainfall Amount
Annual rainfall is larger in higher observatory. In the Middle Awash River Basin area, annual rainfall is 400–600 mm in the land with elevation of around EL1,000 m or low. The high lands with elevation of 1,500 m or higher receive annual rainfall of 800–1,200 mm.
d. Basin mean rainfall over the Middle Awash River Basin
The annual mean rainfall over the Middle Awash River Basin was calculated by the Thiessen method. The method uses a graphical technique to calculate station weights based on the relative areas of each measurement station in the Thiessen polygon network. The individual weights are multiplied by the station’s point rainfall and the values are summed to obtain the areal average rainfall. The Thiessen polygon network can be generated by connecting intersection points of mediators of triangular network of rainfall observatories.
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Historical trend of the annual mean rainfall over the Middle Awash River Basin for current 30 years (1983–2012) is depicted in Figure 1.1.9 together with the annual rainfall data at three representative rainfall stations, i.e., Addis Ababa, Melkasa, and Metehara, for upstream, middle-reaches, and downstream areas, respectively.
0
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400
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800
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1983
1984
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1986
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Annu
al R
ainf
all (
mm
)
Year
Addis AbabaMelkasaMeteharaBasin Mean
Source: the Project Team, Data: NMA’s daily rainfall data
Figure 1.1.9: Historical Trend of Annual Rainfall in the Middle Awash River Basin
The average annual mean rainfall at the Middle Awash River Basin for the period 1983–2012 is 876 mm, while the average annual point rainfall at Addis Ababa, Melkasa, and Metehara is 1,283 mm, 818 mm, and 508 mm, respectively.
1.1.3 Evaporation
a. Data availability
Daily evaporation (Piche) data is collected from NMA. The data for the following 11 observatories are available in hand-written format with plenty of missing data.
64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05Abomsa 1,630 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 26% 99% 1% 100% 3% 3% 100% 100% 100% 100% 5% 0% 3% 1% 17% 57% 75% 100%
Addis Ababa 2,386 69% 100% 10% 2% 75% 17% 0% 0% 10% 3% 10% 100% 22% 100% 100% 100% 100% 100% 100% 100% 100% 1% 1% 0% 1% 1% 0% 2% 40% 2% 2% 3% 3% 2% 2% 1% 3% 1% 2% 0% 0% 1%
Ambo Agriculture 2,068 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 77% 100% 100% 24% 5% 29% 71% 8% 100% 100% 100% 100% 100% 100% 100% 100% 92% 67% 9% 5% 1% 2% 0%
Debre Zeit 1,900 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 67% 100% 21% 2% 100% 100% 100% 100% 100% 10% 0% 0% 0% 2% 17% 28% 0% 0% 20% 28% 8%
Debre Berhan 2,750 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 2% 13% 4% 1% 4% 13% 39% 1% 76% 100% 100% 92% 1% 1% 1% 1% 0%
Gelemso 1,739 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 58% 2% 2% 0% 0%
Kulumsa 2,211 100% 100% 100% 100% 100% 100% 100% 100% 0% 4% 8% 10% 5% 9% 20% 15% 10% 10% 6% 11% 7% 4% 2% 16% 0% 0% 1% 0% 0% 1% 40% 85% 2% 2% 2% 0% 0% 0% 0% 0% 0% 1%
Metehara 944 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 1% 15% 6% 16% 19% 1% 2% 0% 0% 0% 0% 3% 5% 9% 1% 3% 0% 22% 44% 0% 1%
Mieso Mission 1,332 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 41% 0% 18% 100% 100% 100% 100% 100% 100% 100% 100% 2% 0% 1% 1% 0% 0%
Shola Gebeya 2,500 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 1% 1% 10% 1% 0% 0% 0% 0% 0%
Woliso Giyon 2,058 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 10% 1% 24% 2% 0% 1% 1% 6% 45%
Rate of Missing Data: : more than 90% : 50% to 90% : 25% to 50% : less than 25% : Complete data (0%)
YearStation Elevation
(m amsl)
Note: Locations of the above observatories are shown in Figure 1.1.6. Source: the Project Team, Data: NMA’s daily evaporation data
Figure 1.1.10: List of Evaporation Observatories with Available Data
b. Estimation of monthly mean evaporation
Monthly evaporation data are estimated on the basis of the daily evaporation data through averaging the total evaporation for the months without missing data. For example, in an
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observatory, if the complete data for the month of January is available in 1998, 2000, and 2005, the monthly mean evaporation at this observatory is estimated as the simple average of the total evaporation in January for those 3 years.
The estimated monthly mean evaporation data at the 11 observatories are shown in Table 1.1.2.
Table 1.1.2: Monthly Mean Evaporation at 11 Observatories Unit: mm
Abomsa Addis Ababa AmboAgriculture Debre Zeit Debre
Berhan Gelemso Kulumsa Metehara MiesoMission
SholaGebeya
WolisoGiyon
Elevation(m amsl) 1,630 2,386 2,068 1,900 2,750 1,739 2,211 944 1,332 2,500 2,058
Jan 190 165 217 193 153 244 200 250 204 152 260Feb 203 167 229 233 173 288 195 245 215 202 290Mar 226 184 229 227 163 242 207 272 222 192 259Apr 232 153 195 221 147 180 192 242 222 194 245May 303 170 185 238 193 150 197 288 289 253 177Jun 298 104 83 150 163 139 147 306 309 174 80Jul 224 61 50 100 68 131 115 234 267 78 51
Aug 163 58 47 92 56 116 96 185 222 64 51Sep 144 89 62 117 85 108 93 198 176 104 76Oct 184 161 161 222 127 162 203 273 242 159 178Nov 205 165 193 226 143 237 217 274 228 164 265Dec 210 169 216 214 151 244 207 255 197 160 306
Total 2,585 1,646 1,867 2,232 1,622 2,240 2,069 3,023 2,794 1,895 2,239 Note: Locations of the above observatories are shown in Figure 1.1.6. Source: the Project Team, Data: NMA’s daily evaporation data The annual evaporation varies between 1,622 mm at Debre Berhan (outside the Awash but adjoining) and 3,023 mm at Metehara. Monthly evaporation at three observatories, i.e., Addis Ababa (EL 2,386 m), Debre Zeit (EL 1,900 m), and Metehara (EL 944 m), is graphically shown in Figure 2.11.
0
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350
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rM
ay Jun Jul
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)
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ay Jun Jul
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ay Jun Jul
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Nov De
c
Evap
orat
ion
(mm
)
Month
Addis Ababa Debre Zeit Metehara Source: the Project Team, Data: NMA’s daily evaporation data
Figure 1.1.11: Monthly Evaporation at Three Observatories
Evaporation shows its minimal value in the main rainy season, July to September. There is no dominant peak of monthly evaporation and the amount is constantly high during dry and minor rainy seasons.
c. Relationship between elevation and evaporation
The relationship between elevation and annual evaporation is plotted on the graph as shown in Figure 1.1.12. Clear correlation is observed between elevation and potential evaporation.
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R² = 0.9096
0
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1,500
2,000
2,500
3,000
1,000 1,500 2,000 2,500 3,000 3,500
Elev
atio
n (M
SL)
Evaporation [mm]
Source: the Project Team, Data: NMA’s daily evaporation data
Figure 1.1.12: Relationship between Elevation and Annual Evaporation
d. Comparison between rainfall and evaporation
Annual rainfall and evaporation are compared for 11 observatories as shown in Table 1.1.3. The table shows high potential of evaporation in the target area.
Table 1.1.3: Comparison between Annual Rainfall and Evaporation
Meteorological Station
Elevation (m amsl)
Annual Rainfall (mm)
Annual Evaporation
(mm)
Ratio (R/E) Classification*
Abomsa 1,630 916 2,585 0.35 Semi-arid Addis Ababa Obs 2,386 1,223 1,646 0.74 Sub-humid Ambo Agriculture 2,068 1,044 1,867 0.56 Sub-humid Debre Zeit 1,900 852 2,232 0.38 Semi-arid Debre Berhan 2,750 921 1,622 0.57 Sub-humid Gelemso 1,739 1,047 2,240 0.47 Semi-arid Kulumsa 2,211 829 2,069 0.40 Semi-arid Metehara 944 508 3,023 0.17 Arid Mieso Mission 1,332 749 2,794 0.27 Semi-arid Shola Gebeya 2,500 914 1,895 0.48 Semi-arid Woliso Giyon 2,058 1,232 2,239 0.55 Sub-humid
Mean 1,956 930 2,201 0.42 * UNESCO’s classification summarized as follows:
R/E < 0.03: Hyper-arid zone 0.03 <R/E < 0.20: Arid zone 0.20 < R/E < 0.50: Semi-arid zone 0.50 < R/E < 0.75: Sub-humid zone
Source: the Project Team, Data: NMA’s daily rainfall and evaporation data As shown in Table 1.1.3, the annual rainfall ranges 17%–74% of the annual evaporation in the Middle Awash area. The ratio is higher in the upstream including Addis Ababa, while that is low in the downstream area such as Metehara.
According to the climatic zone classification by United Nations Educational, Scientific and Cultural Organization (UNESCO), the Middle Awash River Basin is mostly classified into semi-arid zone. Areal distribution of climatic zones is delineated as in Figure 1.1.13.
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Source: the Project Team, Data: NMA’s daily rainfall and evaporation data
Figure 1.1.13: Climatic Zone Classification in the Middle Awash River Basin
1.1.4 Temperature and other data
a. Collected data
Climatic data of i) minimum/maximum temperature, ii) relative humidity, and iii) sunshine hours are collected on a monthly basis from NMA as shown in Table 1.1.4.
Table 1.1.4: Period of Collection of the Climatic Data
Meteorological Station Temperature Relative Humidity Sunshine Hours
Abomsa 1977–2013 1988–2013 2010–2012 Kulumsa 1971–2013 1972–2013 2010–2013 Gelemso 1986–2013 2010–2013 2010–2012 Addis Ababa Obs 1951–2013 1949–2013 2011–2013 Ambo Agriculture 1954–2013 2010–2013 2010–2013 Debre Berhan 1957–2013 1965–2013 2010–2012 Melkasa (IAR) 1977–2013 1965–2013 1977–2013 Woliso Giyon 1953–2013 2010–2013 2013 Metehara (NMSA) 1984–2013 - - Awash Arba 2008–2013 - - Debre Zeit (AF) 1951–2012 - - Meiso Mission 1952–2006 - - Melka Were 1974–2001 - - Shola Gebeya 2006–2013 - -
Source: the Project Team, Data: NMA’s climatic data b. Long-term trend of temperature
Figure 1.1.14 and Figure 1.1.15 show the historical trend of maximum and minimum temperatures of Addis Ababa and Debre Zeit, where long-term data are available, together
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with linear trend line and 5-years moving average.
y = 0.0156x - 5.3019
y = 0.0455x - 82.876
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010
Tem
pera
ture
(o C)
Year
Max. Temperature
Min. Temperature
Trend L. (Max. T)
5-yr Moving Average (Max. T)
Trend L. (Min. T)
5-yr Moving Average (Min. T)
Source: the Project Team, Data: NMA’s climatic data
Figure 1.1.14: Historical Trend of Temperature at Addis Ababa (1951–2012)
y = 0.0106x + 8.0077
y = -0.0132x + 34.254
0
5
10
15
20
25
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35
1950 1960 1970 1980 1990 2000 2010
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pera
ture
(o C)
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Max. Temperature
Min. Temperature
Trend L. (Max. T)
5-yr Moving Average (Max. T)
Trend L. (Min. T)
5-yr Moving Average (Min. T)
Source: the Project Team, Data: NMA’s climatic data
Figure 1.1.15: Historical Trend of Temperature at Debre Zeit (1953–2012)
Upward trend is seen for both maximum and minimum temperatures at Addis Ababa. The gradient is larger in minimum temperature. On the other hand, although very slight upward tendency is observed for the maximum temperature at Debre Zeit, the minimum temperature does not show the upward tendency.
c. Summary of climatic data
Maximum and minimum temperatures and relative humidity in and around the Middle Awash River Basin is summarized in Table 1.1.5 and Figure 1.1.16.
Table 1.1.5: Temperature, Relative Humidity, and Sunshine Hours at Several Stations in and around the Middle Awash River Basin
Station Elevation (m a.m.s.l)
Max. Temperature
(°C)
Min. Temperature
(°C)
Annual Mean
Temperature (°C)
Annual Mean Relative
Humidity (%)
Annual Mean Sunshine
Hours (hours/day)
Abomsa 1,630 31.0 (Jun.) 13.2 (Dec.) 21.9 59.3 7.5Addis Ababa Obs 2,386 24.9 (Mar.) 7.7 (Dec.) 16.5 60.4 6.6Ambo Agriculture 2,068 28.4 (Mar.) 10.5 (Nov.) 18.9 61.2 6.4Awash Arba 780 38.9 (Jun.) 14.3 (Dec.) 26.8 - -Debre Berhan 2,750 22.0 (Jun.) 2.8 (Nov.) 13.1 64.7 -Debre Zeit 1,900 28.6 (May) 8.6 (Dec.) 18.9 - -Gelemso 1,739 28.1 (Mar.) 10.0 (Nov.) 20.0 64.0 6.7Kulumsa 2,211 25.2 (Mar.) 7.8 (Dec.) 16.6 65.8 7.0Melka Werer 740 38.1 (Jun.) 15.3 (Jan.) 26.7 - -Melkasa 1,540 31.2 (May) 10.6 (Nov.) 21.2 64.8 8.4
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Station Elevation (m a.m.s.l)
Max. Temperature
(°C)
Min. Temperature
(°C)
Annual Mean
Temperature (°C)
Annual Mean Relative
Humidity (%)
Annual Mean Sunshine
Hours (hours/day)
Metehara 944 36.9 (Jun.) 13.6 (Dec.) 25.8 30.4 8.5Mieso Mission 1,332 33.3 (Jun.) 10.5 (Dec.) 22.7 - -Shola Gebeya 2,500 22.0 (May) 6.5 (Dec.) 14.7 - -Wilso Giyon 2,058 27.6 (Mar.) 11.7 (Sep.) 18.9 62.3 --: Data is not available or has not been collected.
Source: the Project Team, Data: NMA’s climatic data
Source: the Project Team, Data: NMA’s climatic data
Figure 1.1.16: Monthly Temperature and Relative Humidity at Several Stations in and around the Middle Awash River Basin
Maximum temperature is observed in the late small rainy season or in the beginning of the main rainy season, i.e., from March to June, at every observatory. In the main rainy season, although the maximum temperature reduces, the minimum temperature is higher. The fluctuation of temperature is, therefore, small in the main rainy season. The maximum temperature reaches more than 36 °C at the stations of downstream regions such as Awash Arba, Melka Werer, and Metehara. The temperature drops less than 10 °C in the high lands such as Addis Ababa, Debre Zeit, Kulumsa, and Shola Gebeya.
In terms of relative humidity, the peak is observed in the main rainy season and annual mean value ranges 60%–65% except for the points in dry regions such as Metehara, where annual mean relative humidity is only 30%.
d. Estimation of reference evapotranspiration at the observatories
Reference evapotranspiration (ETo) is the basic information to estimate ETo from the basin. Although it cannot be measured directly, several estimation methods are proposed. Among
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them, Food and Agriculture Organization of the United Nations (FAO) recommends Penman–Monteith method1 as the sole standard method and is widely applied worldwide.
The FAO Penman–Monteith method requires radiation, air temperature, air humidity, and wind speed data. Since the method allows us to estimate ETo even in the case of missing climatic data, the estimation is made applying the collected climatic data. The result is shown in Figure 1.1.17.
Source: the Project Team, Data: NMA’s climatic data
Figure 1.1.17: Monthly Reference Evapotranspiration (ETo) in and around the Middle Awash River Basin
As seen in this figure, ETo varies between 1,252 mm/year at Shola Gebeya and 2,224 mm/year at Metehara. ETo in and around the Middle Awash River Basin is corresponding to 65%–80% of evaporation observed by NMA (see section 1.1.3 also).
1.2 Review of hydrology data
1.2.1 Hydrological stations in the middle Awash River Basin
Following table shows the location of hydrological stations managed by MoWIE as of 2013:
1 http://www.fao.org/docrep/x0490e/x0490e00.htm#Contents
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Table 1.2.1: List of Hydrological Stations SL MAIN SUB UTM INSTA. AREA AVG. REGIONALNo. CATCHM. CATCHM. STN. No. RIV/LAKE SITE LAT. LON. North East DATE KM2 ELEV. OFFICE GOVERN.
1 AWASH (03) UPPER (1) 031001 BERGAA Nr. ADDIS ALEM 9d01'n 38d21'e 996668 428556 15-1-75 248 CEN OROMIYA2 AWASH (03) UPPER (1) 031002 HOLETA Nr. HOLETA 9d05'n 38d31'e 1004010 446886 16-1-75 119 CEN OROMIYA3 AWASH (03) UPPER (1) 031003 TEJI Nr. ASGORI 8d47'n 38d20'e 970876 426678 11-75 663 2415 CEN OROMIYA4 AWASH (03) UPPER (1) 031004 AKAKI @ AKAKI 8d53'n 38d47'e 981872 476177 12-12-80 884 2100 CEN ADDIS ABABA
5 AWASH (03) UPPER (1) 031005 L.BISHEFTU @ DEBRE ZEIT 8d44'n 38d59'e 965283 498167 15-2-81 10 CEN OROMIYA6 AWASH (03) UPPER (1) 031012 AWASH @ MELKA KUNTIRE 8d42'n 38d36'e 961622 455998 11-62 4456 2332 CEN OROMYA7 AWASH (03) UPPER (1) 031013 AWASH @ MELKA HOMBOLE 8d23'n 38d47'e 950551 476159 6-62 7656 2300 CEN OROMYA8 AWASH (03) UPPER (1) 031014 MOJO @ MOJO VILLAGE 8d36'n 39d05'e 950545 509170 8-62 1264 2175 CEN OROMYA9 AWASH (03) UPPER (1) 031015 KELETA Nr. SIRIE (ARSI) 8d17'n 39d24'e 915560 544050 8-62 747 2800 CEN OROMYA
10 AWASH (03) UPPER (1) 031016 AWASH @ WONJI 8d27'n 39d14'e 933970 525685 3-64 11690 CEN OROMYA11 AWASH (03) UPPER (1) 031017 AWASH BELOW KOKA DAM 8d28'n 39d10'e 935809 518345 9-61 11219 CEN OROMYA12 AWASH (03) UPPER (1) 031018 HOT SPRING D.S.OF KOKA 8d27'n 39d12'e 933968 522015 -9-68 CEN OROMIYA13 AWASH (03) UPPER (1) 031019 KESSEM @ BEKE 9d10'n 39d04'e 1013188 507324 20-3-84 50 CEN OROMIYA14 AWASH (03) UPPER (1) 031020 AWASH Nr. BELLO 8d51'n 38d25'e 978231 435855 1-5-86 2569 CEN OROMYA15 AWASH (03) UPPER (1) 031021 LIT. AKAKI D/S GEFERSA DAM 9d02'n 38d42'e 998461 467028 4-8-89 131 CEN ADDIS ABABA
16 AWASH (03) UPPER (1) 031022 HORA @ DEBRE ZEIT 8d46'n 38d59'e 968968 498167 23-8-86 9 CEN OROMIYA17 AWASH (03) UPPER (1) 031023 KURIFTU Nr. DEBREZEIT 8d46'n 38d58'e 968968 496334 22-8-86 33 CEN OROMIYA18 AWASH (03) UPPER (1) 031025 BISHO (GUDO) Nr. DEBREZEIT 8d44'n 38d59'e 965283 498167 22-8-86 3 CEN OROMIYA19 AWASH (03) UPPER (1) 031026 MUTINCHA D/S LEGEDADI DAM 9d03'n 38d55'e 1000291 490842 14-9-89 173 CEN ADDIS ABABA
20 AWASH (03) MIDDLE (2) 032001 LAKE BESKA Nr. METEHARA 8d54'n 39d52'e 983819 595290 29-7-76 596 1176 CEN OROMIYA21 AWASH (03) MIDDLE (2) 032002 ARBA Nr. ABOMUSSA 8d34'n 39d49'e 946955 589872 4-23-82 140 2329 CEN OROMIYA22 AWASH (03) MIDDLE (2) 032003 AWASH @ METAHARA 8d51'n 39d51'e 978287 593470 6-62 16417 CEN OROMYA23 AWASH (03) MIDDLE (2) 032004 AWASH @ AWASH STATION 8d59'n 40d11'e 993130 630082 6-62 19111 EAS AFAR24 AWASH (03) MIDDLE (2) 032005 KESSEM @ AWARA MELKA 9d09'n 39d57'e 1011482 604381 6-62 3113 2131 CEN AFAR25 AWASH (03) MIDDLE (2) 032009 ARBA @ BORDEDE 9d01'n 40d21'e 996879 648393 4-2-84 72 EAS OROMIYA26 AWASH (03) MIDDLE (2) 032015 AWASH @ MELKA SEDI 9d12'n 40d07'e 1017063 622679 APR. 82 21520 EAS AFAR27 AWASH (03) MIDDLE (2) 032016 AWASH @ MELKA WERER. 9d19'n 40d10'e 1029981 628130 SEP. 72 31183 EAS AFAR28 AWASH (03) MIDDLE (2) 032017 AWASH @ NURA HERA 8d32'n 39d35'e 943223 564199 JUNE 75 14173 CEN OROMYA29 AWASH (03) AKAKI Nr. ABA SAMUEL 8d45'n 38d43'e 967138 468836 1476 CEN OROMYA30 AWASH (03) LAKE KOKA Nr. KOKA DAM 8°28'2.63"N 39° 9'19.97"E 9818 CEN OROMYA31 AWASH (03) AWASH Nr. GINCHI 9d01'n 38d08'e 996718 404740 76 CEN OROMIYA
Source: MoWIE
The water level is observed 2 times a day by gauge reader. The average of the readings of the day is recorded as the daily water level. According to the interview with the Hydrological Directorate of MoWIE, the reference elevation such as elevation of the zero point of gauge is not surveyed. Therefore, water level data is not managed with the datum of meter above mean sea level. Since this situation often causes following disadvantages, water level data are recommended to be managed in the elevation datum:
Data consistency may be lost easily when relocation or reinstallation of staff gauges are undertaken.
Relationship of water level among observatories such as difference an water slope surface, etc. cannot be calculated directly from the data.
Metehara Water Level Gauging Station Awash River at Metehara
Daily discharge is estimated applying discharge rating curve which is used to calculate the discharge amount by power function of water level. The rating curve is reviewed and updated only when hydrologists of MoWIE recognizes the need to do so. No routine updating is undertaken. The discharge at the stations is measured once or twice per year on average for the purpose of checking the applicability of existing discharge rating curves, according to the interview with the Directorate.
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1.2.2 River flow
Mean 10-day runoff at several water level gauging stations on the Middle Awash is calculated based on the daily discharge data from 1980 to 2009 and presented in Figure 1.2.1 and Table 1.2.2 below:
0
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l (m
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1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Rai
nfal
l (m
m)
Dis
char
ge (m
3 /sec
)
Source: the Project Team, Data: MoWIE’s hydrologic data and NMA’s rainfall data
Figure 1.2.1: Mean 10-day Runoff Hydrograph at Major Stations on the Middle Awash
Table 1.2.2: Mean 10-day Runoff at Major Stations on the Middle Awash Melka Kuntire
Melka Homble
Below Koka Dam Nura Hera Awash Sta. Melka Werer
Catchment (km2) 4,580 7,780 11,300 14,550 21,230 29,280
Dis
char
ge (m
3 /sec
)
Jan 1 1.5 3.7 36.7 34.9 32.2 33.42 1.6 3.9 36.3 34.4 33.6 35.23 1.4 4.3 36.0 34.3 35.7 36.7
Feb 1 1.4 4.0 36.1 31.9 34.9 33.92 1.4 4.2 34.7 33.1 38.7 40.03 1.4 4.7 35.4 36.2 33.7 39.1
Mar 1 1.8 6.0 35.8 35.3 35.3 40.82 2.0 5.1 34.9 36.1 40.8 46.23 2.6 6.2 35.6 32.4 39.3 49.2
Apr 1 4.0 8.9 35.1 35.2 47.8 52.42 3.7 8.8 34.6 34.0 42.9 48.93 4.0 9.1 35.1 35.1 43.1 46.3
May 1 5.3 8.0 35.0 30.3 37.2 40.22 4.1 8.9 37.7 36.0 42.6 40.83 4.0 9.0 37.0 44.6 43.8 37.8
Jun 1 6.9 11.4 38.7 39.2 38.1 31.62 11.2 17.5 38.7 36.8 41.2 28.93 21.7 29.6 36.2 41.6 42.6 33.7
Jul 1 38.6 49.3 37.1 52.2 61.5 51.92 63.5 85.7 36.2 60.6 81.0 81.93 102.0 144.8 39.9 58.0 99.6 120.5
Aug 1 129.8 191.7 43.6 66.3 106.1 150.72 146.2 223.2 65.2 73.9 131.0 184.33 149.4 216.9 94.7 88.9 140.8 186.8
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Melka Kuntire
Melka Homble
Below Koka Dam Nura Hera Awash Sta. Melka Werer
Sep 1 121.5 175.1 110.2 116.2 159.7 174.82 80.9 113.2 101.6 110.8 158.2 150.53 39.2 61.0 66.8 83.6 107.4 108.2
Oct 1 19.0 26.4 49.9 60.6 69.2 69.62 10.0 17.5 40.6 42.3 49.2 54.53 5.8 9.9 36.9 38.0 40.0 48.2
Nov 1 3.5 8.3 35.6 34.8 36.4 41.62 2.7 6.6 34.7 36.6 35.8 36.03 2.2 5.8 34.2 38.3 31.4 33.0
Dec 1 1.9 4.9 35.5 37.5 32.3 33.62 1.8 4.3 35.5 36.8 31.4 33.93 1.6 3.9 35.7 36.4 31.8 33.0
Ann. Mean (m3/sec) 27.8 41.7 44.0 47.6 58.5 64.1Height (mm/yr) 191 169 123 103 87 69
Source: the Project Team, Data: MoWIE’s hydrologic data According to the information above:
Peak runoffs are observed during the period from the middle of August to the beginning of September while peak of rainfall is observed in July and August;
The Lake Koka releases constant discharge of approximately 35 m3 per second in dry season;
Annual runoff height at Melka Werer, the downstream end of the Middle Awash, is 69 mm, and this is less than 8% of the annual basin mean rainfall of 876 mm (1983 – 2012).
1.3 Hydrological analysis
1.3.1 Introduction
a. Purpose of the hydrological analysis
One of the main purposes of the hydrological analysis project is to evaluate the available groundwater resources in the Middle Awash River Basin and formulate a groundwater development plan based on the evaluation. The hydrological analysis is to estimate annual groundwater recharge in the Middle Awash River Basin. In this section, groundwater recharge, which is equivalent to available groundwater resources, is estimated using general relationship between river runoff and groundwater recharge, and other relevant data/information.
b. Procedure
The analysis is undertaken through the procedure shown in Figure 1.3.1.
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Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.1: Procedure of the Hydrological Analysis
First, river flow at selected discharge stations in the Middle Awash River Basin is analyzed to obtain base flow amount (or index), which is considered to be equivalent to groundwater recharge. The relationship between base flow amount and catchment area is then analyzed. Second, total river runoff at the selected discharge stations is compared with the stations’ basin mean rainfall amount to analyze the relationship between runoff coefficient and catchment area. Further, the groundwater recharge in the sub-basins is estimated by applying the relationships analyzed above.
c. Sub-basins
The Middle Awash River Basin is divided into 13 sub-basins as shown in Figure 1.3.2.
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SB5-L
SB2-L
SB4-R
SB3-R
SB1-R
SB5-RSB1-L
SB2-R
SB-BSK-W
SB3-L
SB-BSK
SB4-L-U
SB4-L-D
Lake Ziway
Lake Koka
Lake Beseka
Lake Abijata
Lake DendiLake Ala Semite
Lake Langano
Lake Wenchi
Lake Goletsho
Awash Wenz
Bilat
e
Muger Wenz
Wab
e Sheb
ele
Wenz
Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.2: Basin Division for Groundwater Recharge Estimation
Basic concepts based on which the basin is divided are as follows:
The basin will be divided at existing stream flow gauging station (hereafter referred to as “SFGS”) or water level gauging station sites;
The basin will be divided by the Awash River, namely the left and right bank sides;
Smaller sub-basins will be extracted for Lake Beseka and adjacent area.
Outlines of the sub-basins are tabulated below. As seen, the catchment areas of sub-basins vary from 310 km2 to 5,710 km2:
Table 1.3.1: Summary of Sub-basins
No Name Outlet Area [km2] Description
1 SB1-L Awash 2,068 Catchment of the left bank side of the Awash upstream “Melka Kuntire” SFGS (stream flow gauging station).
2 SB1-R Awash 2,508 Catchment of the right bank side of the Awash upstream “Melka Kuntire” SFGS.
3 SB2-L Awash 4,860 Catchment of the left bank side of the Awash between “Below Koka Dam” and “Melka Kuntire” SFGSs
4 SB2-R Awash 1,859 Catchment of the right bank side of the Awash between “Below Koka Dam” and “Melka Kuntire” SFGSs
5 SB3-L Awash 508 Catchment of the left bank side of the Awash between “Nura Hera” and “Below Koka Dam” SFGSs
6 SB3-R Awash 2,743 Catchment of the right bank side of the Awash between “Nura Hera” and “Below Koka Dam” SFGSs
7 SB4-L-U Awash 435 Catchment of the left bank side of the Awash between the bridge on the Awash at the entrance of Metehara Sugar Plantation and “Nura Hera” SFGS
8 SB4-L-D Awash 312 Catchment of the left bank side of the Awash between “Awash Station” SFGS and the bridge on the Awash at the entrance of Metehara Sugar Plantation
9 SB4-R Awash 3,367 Catchment of the right bank side of the Awash between “Awash Station” and “Nura Hera” SFGSs
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No Name Outlet Area [km2] Description
10 SB5-L Awash 5,710 Catchment of the left bank side of the Awash between “Melka Werer” and “Awash Station” SFGSs
11 SB5-R Awash 2,347 Catchment of the right bank side of the Awash between “Melka Werer” and “Awash Station” SFGSs
12 SB-BSK-W Depression (no outlet is confirmed topographically) 2,041 Catchment in the western side of the Lake Beseka Catchment
13 SB-BSK Lake Beseka, Awash (through a Drainage Channel) 532 Catchment of the Lake Beseka
Total 29,289 Source: the Project Team, Data: Result of hydrology survey in this Project
1.3.2 River flow analysis
a. Relationship between river flow and groundwater flow
As shown in Figure 1.3.3, the river water is formed by direct runoff due to precipitation and groundwater discharge to the river.
Source: Reference (1)
Figure 1.3.3: Precipitation and Process of River Water Formation
Direct runoff can be further divided into the following three components:
Surface run off that does not infiltrate into the ground and directly flows into river streams
Rapid interflow that has once infiltrated into the ground but quickly discharges into river streams before it reaches the groundwater table.
Slow interflow that has once infiltrated into the ground but discharges into river streams before it reaches the groundwater table. This component takes much longer time than the rapid interflow component to discharge into a river.
The groundwater levels that are recharged by direct precipitation are usually high compared to the surface water level. Thus the groundwater usually flows from higher to lower levels into river streams.
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Direct runoff due to precipitation usually continues only a few hours after the rain stops or maximum for a few days, in the case of large river basins. The river flow rapidly increases due to the inflow of a large amount of water into river streams in a short time.
In contrast, the velocity of the flow is much smaller in the case of groundwater inflow although the rate of inflow from the groundwater depends on the permeability of the aquifer and the hydraulic head of the groundwater. Thus, groundwater discharge continues even on days and seasons of no rain. This is how river streams are replenished by groundwater inflow under no-rain conditions.
Based on the above-mentioned mechanism, the river flow can be separated into direct runoff component and groundwater inflow component.
b. Method of groundwater recharge analysis
There are several methods to directly calculate the groundwater recharge and the most reliable ones are to measure directly with a lysimeter or to use the tank model based on the daily precipitation and groundwater level data. However, there are neither lysimeter measurement data nor long-term groundwater level records that can be used for the analysis. Therefore, the groundwater recharge cannot be directly calculated.
On the other hand, the recharge and discharge amounts are more or less equal in a long-term hydrological cycle. Otherwise, the level of groundwater surface is either on the rise or on the decline. This means that if groundwater discharge amount is calculated, the recharge amount can also be estimated. The groundwater discharge is composed of the following components:
Discharge into rivers
Discharge into lakes
Discharge to outside the basin
Groundwater use by pumping at wells
The most important component among the above four is considered to be the (groundwater) discharge into river streams, and thus, it will be necessary to calculate the amount/ratio of groundwater component in river flows. The following sections discuss the process of separating the groundwater component.
c. Separation of river flow components (BFI calculation)
The ratio of the groundwater component in a river flow is defined as base flow index (hereafter referred to as “BFI”). Many methods have been developed and used to separate the groundwater (base flow) component and direct runoff component from daily river flow data. However, the result will naturally differ depending on the method employed. In this analysis, the following two methods (programs) were selected since both are considered to be reliable:
Program 1: PART (United States Geological Survey: USGS, 2007)2. The computer program uses stream flow partitioning to estimate a daily record of groundwater discharge under the stream flow record. The method designates groundwater discharge to be equal to stream flow on days that fit a requirement of antecedent recession, linearly interpolates groundwater discharge for other days, and is applied to a
2 http://water.usgs.gov/ogw/part/
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long period of record to obtain an estimate of the mean rate of groundwater discharge.
Program 2: BFI (United States Bureau of Reclamation: USBR, 2013)3. This program begins by partitioning the year into N-day periods and determining the minimum flow within each period. These minimum flows are the potential turning points on the base-flow hydrograph. (If the year is not evenly divisible by N, any remaining days will be included in the last period of the year). When several days within one period are tied for the lowest flow, the earliest day will be considered the minimum, except during the last N-day period of each year, when the minimum will be considered to occur on the latest day. To determine the turning points on the base-flow hydrograph, the collection of N-day minimum flows is processed using the following turning-point test:
Given three adjacent N-day minimum flows, Q0, Q1, and Q2,
Q1 is a turning point IF Q1* f <= Q0 and Q1* f <= Q2
where, f is a turning-point test factor that must be greater than 0 and should be less than 1.
If Q1 is zero, it will always be a turning point. If either Q0 or Q2 is equal to zero, then the test is only performed against the non-zero value. If both Q0 and Q2 are zero, Q1 cannot be a turning point unless it is zero.
d. Selection of streamflow gauging stations for BFI calculation
Hydrological stations subject to BFI calculation are selected on the basis of the following two criteria:
The stations shall not be affected by the artificial control.
The stations shall have time series discharge data of at least 5 years without missing.
Based on the above criteria, following 12 stations are selected for the BFI calculation:
3 http://www.usbr.gov/pmts/hydraulics_lab/twahl/bfi/
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Wilso Giyon
Ambo Agriculture
Asgori
Addis Ababa Obs.
Debre Zeit (AF)
Homble
Kulumsa
Melkasa (IAR)
Nazret
Abomsa
Metehara
Gelemso
Mieso Mission
Debre Berhan
Melka Homble
Melka Kuntire
Bello
Asgori
Addis Alem
GinchiHoleta
Akaki
Beke
Sire
Abomsa
Awara Melka
Rainfall Gauging StationStreamflow Gauging Station(Selected)
Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.4: Location Map of Selected Stations for BFI Calculation
Table 1.3.2: Selected Stations for BFI Calculation Station Name River
Name Area (km2)
Number of Years
Period
Abomsa Arba 140 5 1995–1999 Addis Alem Berga 248 18 1984, 1989–1991, 1993–2002, 2004–2007 Akaki Akaki 884 14 1983–1984, 1986–1992, 2000–2004 Awara Melka Kesem 3,113 20 1983–1984, 1986–2000, 2003–2004, 2006 Asgori Teji 663 11 1983–1985, 1987–1991, 1996, 2001, 2007 Beke Kesem 50 14 1986, 1988–1989, 1993, 1995–1997, 1999–2003,
2005–2006 Bello Awash 2,569 11 1987–1990, 1992, 1994, 1996–1997, 2000, 2004, 2008 Ginchi Awash 76 12 1994–1995, 1997, 1999–2007 Holeta Holeta 119 16 1988, 1991, 1994–2002, 2004–2008 Melka Homble Awash 7,780 27 1983–2009 Melka Kuntire Awash 4,580 24 1983–1984, 1986–2005, 2007–2008 Sire Keleta 747 13 1983–1984, 1985, 1987–1988, 1990–1993, 1995, 1997,
1999–2000 Source: the Project Team, Data: Result of hydrology survey in this Project e. Example of flow component separation (BFI calculation)
Figure 1.3.5 presents hydrographs showing examples of base flow separation results. The BFI is the proportion of the base flow volume (area below the solid line in the hydrographs) to the river flow volume (area below the dotted line).
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1
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harg
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Melka Homble on the Awash River (1983) Awara Melka on the Kesem River (1996)
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Akaki on the Akaki River (2004) Beke on the Kesem River (2000) Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.5: Examples of Base Flow Separation Results
f. Result of BFI calculation
The BFI was calculated using both programs: “PART” and “BFI.” Since results vary considerably by programs and years, the results of the year that is relatively consistent between both programs are adopted for further analysis. Specifically, results that have a difference of 25% or less between “PART” and “BFI” are adopted as reliable BFI. Calculated mean BFI values are shown in Table 1.3.3 together with the duration of the data adopted.
Table 1.3.3: Calculated BFI Values from Flow Separation Analysis Station Name River
Name Area (km2)
PART BFI Min Period Adopted
Abomsa Arba 140 0.28 0.26 0.26 1995–1996, 1998–1999 Addis Alem Berga 248 0.40 0.42 0.40 1984, 1989–1991, 1993, 1996,
1998–2000, 2006–2007 Akaki Akaki 884 0.28 0.32 0.28 1983–1984, 1986–1987, 1990–1992,
2000–2004 Awara Melka Kesem 3,113 0.33 0.33 0.33 1984, 1986, 1990–1991, 1993,
1995–1997, 1999, 2004 Asgori Teji 663 0.27 0.27 0.27 1983–1987, 1989 Beke Kesem 50 0.21 0.25 0.21 1986, 1993, 2000–2001 Bello Awash 2,569 0.74 0.77 0.74 1987–1990, 1996–1997 Ginchi Awash 76 0.21 0.21 0.21 1994, 1997, 1999–2007 Holeta Holeta 119 0.39 0.42 0.39 1988, 1991, 1995–2002, 2004–2008 Melka Homble Awash 7,780 0.52 0.57 0.52 1983–1984, 1987, 1990–1991,
1993–1994, 1996–2000, 2003, 2005, 2007, 2009
Melka Kuntire Awash 4,580 0.57 0.60 0.57 1983, 1986–1988, 1990–1991, 1993–1994, 1996, 1999–2002,
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Station Name River Name
Area (km2)
PART BFI Min Period Adopted
2004–2005, 2007–2008 Sire Keleta 747 0.48 0.46 0.46 1983–1985, 1987–1988, 1990–1993,
1995, 1997, 1999–2000 Source: the Project Team, Data: Result of hydrology survey in this Project The minimum (smaller) BFI value calculated by “PART” and “BFI” programs is considered as the BFI at a gauging station from the conservative view. Figure 1.3.6 shows the calculated BFIs plotted with the catchment area on the x-axis.
Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.6: Relationship between Catchment Area and BFI Values
The graph shows high correlation (r > 0.70) between catchment area and BFI. According to the figure, the larger the catchment area, the larger is the BFI. This is reasonable considering that water originated from precipitation shall travel longer distance and time in larger basins. This may provide more occasions for runoff to percolate in groundwater domain during its travel.
1.3.3 Water balance analysis
a. Runoff coefficient at selected 12 gauging stations
BFI at 12 hydrological stations in the Middle Awash River Basin is estimated in the subsection above. BFI is the percentage of base flow to the total river runoff as explained. Therefore, the groundwater recharge amount can be quantitatively estimated if the river runoff amount is available.
Runoff coefficient at 12 stations is calculated as the percentage of annual river runoff to annual basin mean rainfall. Annual river runoff can be obtained from the daily discharge record. Annual basin mean rainfall is estimated on the basis of the point rainfall data by applying the Thiessen method (see Figure 1.3.4 for the Thiessen polygons). Table 1.3.4 shows the Thiessen ratio for calculation of basin mean rainfall for the catchments of 12 stations.
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Table 1.3.4: Thiessen Ratio for Selected 12 Stations’ Catchments Station Name River Name Area
(km2) Number of
Rainfall Stations
Rainfall Station Thiessen Ratio
Abomsa Arba 140 1 Abomsa 1.00Addis Alem Berga 248 2 Asgori 0.50 Addis Ababa Obs. 0.50Akaki Akaki 884 1 Addis Ababa Obs. 1.00Awara Melka Kesem 3,113 5 Metehara 0.34 Debre Berhan 0.30 Addis Ababa Obs. 0.13 Debre Zeit (AF) 0.06 Nazret 0.17Beke Kesem 50 1 Addis Ababa Obs. 1.00Bello Awash 2,569 4 Asgori 0.60 Addis Ababa Obs. 0.17 Ambo Agriculture 0.16 Wilso Giyon 0.07Ginchi Awash 76 1 Ambo Agriculture 1.00Holeta Holeta 119 1 Addis Ababa Obs. 1.00Melka Homble Awash 7,780 6 Addis Ababa Obs. 0.27 Debre Zeit (AF) 0.10 Homble 0.13 Asgori 0.40 Ambo Agriculture 0.05 Woliso Giyon 0.05Melka Kuntire Awash 4,580 5 Asgori 0.66 Addis Ababa Obs. 0.16 Ambo Agriculture 0.09 Woliso Giyon 0.08 Homble 0.01Sire Keleta 747 2 Melkasa 0.33 Kulumsa 0.67
Source: the Project Team, Data: Result of hydrology survey in this Project Calculated mean annual rainfall and runoff are shown in Table 1.3.5. Annual runoff ranges between 111 mm/year at Bello and 682 mm/year at Beke, while annual rainfall ranges between 806 mm/year at Sire and 1,249 mm/year at Beke.
Table 1.3.5: Mean Annual Runoff and Rainfall for Selected Stations Station Name River
Name Area (km2)
Runoff (mm/yr)
Rainfall (mm/yr)
Runoff Coefficient
Period
Abomsa Arba 140 301 1,018 0.295 1995–1999 Addis Alem Berga 248 357 1,136 0.315 1984, 1989–1991, 1993–2002,
2004–2007 Akaki Akaki 884 331 1,198 0.276 1983–1984, 1986–1992, 2000–2004Awara Melka Kesem 3,113 135 824 0.164 1983–1984, 1986–2000,
2003–2004, 2006 Asgori Teji 663 189 1,115 0.169 1983–1985, 1987–1991, 1996,
2001, 2007 Beke Kesem 50 682 1,249 0.546 1986, 1988–1989, 1993,
1995–1997, 1999–2003, 2005–2006Bello Awash 2,569 111 1,098 0.101 1987–1990, 1992, 1994,
1996–1997, 2000, 2004, 2008 Ginchi Awash 76 364 979 0.372 1994–1995, 1997, 1999–2007 Holeta Holeta 119 393 1,220 0.322 1988, 1991, 1994–2002, 2004–2008Melka Homble Awash 7,780 172 1,066 0.162 1983–2009 Melka Kuntire Awash 4,580 188 1,103 0.171 1983–1984, 1986–2005, 2007–2008Sire Keleta 747 242 806 0.300 1983–1984, 1985, 1987–1988,
1990–1993, 1995, 1997, 1999–2000Source: the Project Team, Data: Result of hydrology survey in this Project
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In general, the larger the catchment area, the smaller is the runoff coefficient. This can be said for the Middle Awash River Basin. The relationship between catchment area and runoff coefficient is depicted in Figure 1.3.7.
Source: the Project Team, Data: Result of hydrology survey in this Project
Figure 1.3.7: Relationship between Catchment Area and Runoff Coefficient
The graph shows high correlation (r > 0.85) between catchment area and runoff coefficient.
b. Annual Groundwater Recharge in the Selected 12 Gauging Stations’ Catchments
Based on the above, annual groundwater recharge (hereafter referred to as “GWR”) can be expressed as follows:
BFICRGWR
where, GWR: Annual groundwater recharge (mm/year) R: Annual basin mean rainfall (mm/year) C: Runoff coefficient (-) BFI: Base flow index (-)
The annual groundwater recharge at selected 12 gauging stations’ catchments is estimated as shown in Table 1.3.6.
Table 1.3.6: Annual Groundwater Recharge in 12 Stations’ Catchments Station Name River
Name Area [km2]
Rainfall (R)[mm/yr]
Runoff Coefficient
(C)
Base Flow Index (BFI)
Groundwater Recharge (GWR) [mm/yr]
GWR/R
Abomsa Arba 140 1,018 0.295 0.26 77 7.6%Addis Alem Berga 248 1,136 0.315 0.40 144 12.7%Akaki Akaki 884 1,198 0.276 0.28 91 7.6%Awara Melka Kesem 3,113 824 0.164 0.33 44 5.4%Asgori Teji 663 1,115 0.169 0.27 50 4.5%Beke Kesem 50 1,249 0.546 0.21 145 11.6%Bello Awash 2,569 1,098 0.101 0.74 82 7.4%Ginchi Awash 76 979 0.372 0.21 76 7.8%Holeta Holeta 119 1,220 0.322 0.39 154 12.6%Melka Homble Awash 7,780 1,066 0.162 0.52 90 8.5%
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Station Name River Name
Area [km2]
Rainfall (R)[mm/yr]
Runoff Coefficient
(C)
Base Flow Index (BFI)
Groundwater Recharge (GWR) [mm/yr]
GWR/R
Melka Kuntire Awash 4,580 1,103 0.171 0.57 108 9.8%Sire Keleta 747 806 0.300 0.46 111 13.8%
Source: the Project Team, Data: Result of hydrology survey in this Project
1.3.4 Results of water balance analysis
The annual groundwater recharge in the divided 13 sub-basins (see Figure 1.3.2 and Table 1.3.1) is estimated in the same procedure as that in 12 stations’ catchments. In this estimation, both BFI and runoff coefficient (C) are assumed to be the function of catchment area as shown below (see Figure 1.3.6 and Figure 1.3.7 also):
BFICRGWR 170.0121.0 ABFI
236.0090.1 AC
where, GWR: Annual groundwater recharge (mm/year) R: Annual basin mean rainfall (mm/year) C: Runoff coefficient (-) BFI: Base flow index (-) A: Catchment area (km2)
The annual rainfall over sub-basins is calculated on the basis of the point rainfall data by applying the Thiessen polygon method (see Figure 1.3.4 for the Thiessen polygons). The Thiessen ratio for each rainfall station is shown in Table 1.3.7 by sub-basins.
The Project for Groundwater Resources Assessment JICA in the Middle Awash River Basin, Final Report (Supporting Report) KOKUSAI KOGYO CO., LTD.
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Table 1.3.7: Thiessen Ratio for Sub-basins
Sub-basin Rainfall StationThiessen
RatioSub-basin Rainfall Station
ThiessenRatio
SB1-L Asgori 0.557 SB4-L-U Metehara (NMSA) 0.237Addis Ababa Obs 0.363 Nazeret 0.123Ambo Agriculture 0.080 Abomsa 0.641
SB1-R Asgori 0.750 SB4-L-D Metehara (NMSA) 1.000Ambo Agriculture 0.096 SB4-R Metehara (NMSA) 0.298Woliso Giyon 0.149 Gelemso 0.101Hombole 0.005 Abomsa 0.601
SB2-L Asgori 0.002 SB5-L Metehara (NMSA) 0.411Addis Ababa Obs 0.306 Debre Berhan 0.384Debre Zeit(AF) 0.481 Addis Ababa Obs 0.064Hombole 0.094 Debre Zeit(AF) 0.057Nazeret 0.116 Nazeret 0.084
SB2-R Asgori 0.047 SB5-R Metehara (NMSA) 0.143Debre Zeit(AF) 0.004 Gelemso 0.663Hombole 0.751 Meiso Mission 0.195Nazeret 0.008 SB-BSK-W Metehara (NMSA) 0.443Melkasa(IAR) 0.057 Nazeret 0.535Kulumsa 0.133 Abomsa 0.021
SB3-L Nazeret 0.445 Melkasa(IAR) 0.001Abomsa 0.012 SB-BSK Metehara (NMSA) 1.000Melkasa(IAR) 0.544
SB3-R Nazeret 0.007Abomsa 0.097Melkasa(IAR) 0.494Kulumsa 0.402
Source: the Project Team, Data: Result of hydrology survey in this Project The annual basin mean rainfall over sub-basins is calculated by applying the Thiessen ratios given in the table. Then, annual basin mean rainfall is multiplied by the runoff coefficient and BFI, which are estimated using the equations stated above. The annual groundwater recharge is estimated as in Table 1.3.8.
Table 1.3.8: Result of Groundwater Recharge Estimation by Sub-basins
SL No.
Sub-basin Area (A)
[km2]
Annual Rainfall (R)
[mm/yr]
Runoff Coefficient
(C) [-]
Base Flow Index (BFI)
[-]
Annual Groundwater Recharge (GWR) GWR/R
[%] [mm/yr] [106 m3/yr]
1 SB1-L 2,068 1,097 0.18 0.44 87.2 180.3 7.9%2 SB1-R 2,508 1,075 0.17 0.46 84.4 211.6 7.8%3 SB2-L 4,860 982 0.15 0.51 73.7 358.4 7.5%4 SB2-R 1,859 867 0.18 0.43 69.4 129.0 8.0%5 SB3-L 508 853 0.25 0.35 74.4 37.8 8.7%6 SB3-R 2,743 832 0.17 0.46 64.9 178.1 7.8%7 SB4-L-U 435 824 0.26 0.34 72.5 31.6 8.8%8 SB4-L-D 312 548 0.28 0.32 49.3 15.4 9.0%9 SB4-R 3,367 806 0.16 0.48 62.0 208.8 7.7%
10 SB5-L 5,710 779 0.14 0.53 57.9 330.8 7.4%11 SB5-R 2,347 870 0.17 0.45 68.6 161.0 7.9%12 SB-BSK-W 2,041 740 0.18 0.44 58.9 120.2 8.0%13 SB-BSK 532 548 0.25 0.35 47.6 25.3 8.7%
All Basin 29,290 876 - - 67.9 1,988.3 7.7%Source: the Project Team, Data: Result of hydrology survey in this Project
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The estimated groundwater recharge ranges between 47 mm/year and 87 mm/year and is equivalent to 7.4%–9.0% of the annual rainfall. It has been reported that the annual mean groundwater recharge in the Awash River Basin (112,700 km2) is about 3,800 million m3 (33.7 mm/year), and this is equivalent to 9.5% of the available water from rainfall in the basin, which is 39,845 million m3 (354 mm/year)4. Therefore, the groundwater recharge estimated here is considered reasonable though the result may be conservative to some degree.
The water balance in each sub-basin is estimated as in Table 1.3.9 by assuming that all losses are incorporated in the form of evapotranspiration.
Table 1.3.9: Water Balance in Sub-basins
SL. No. Sub-basin Area (A)
[km2]
Incoming Outgoing
Annual Rainfall (R) [mm/yr]
Direct Runoff [mm/yr]
Base Flow (Groundwater
Recharge) [mm/yr]
Evapotranspiration [mm/yr]
1 SB1-L 2,068 1,097 110 87 900 2 SB1-R 2,508 1,075 100 84 891 3 SB2-L 4,860 982 71 74 837 4 SB2-R 1,859 867 90 69 707 5 SB3-L 508 853 139 74 639 6 SB3-R 2,743 832 75 65 692 7 SB4-L-U 435 824 141 73 610 8 SB4-L-D 312 548 105 49 394 9 SB4-R 3,367 806 67 62 677
10 SB5-L 5,710 779 52 58 669 11 SB5-R 2,347 870 83 69 719 12 SB-BSK-W 2,041 740 75 59 607 13 SB-BSK 532 548 88 48 412
All Basin 29,290 876 78 68 730 Source: the Project Team, Data: Result of hydrology survey in this Project
Reference
(1) The Study on Groundwater Resources Assessment in the Rift Valley Lakes Basin in the Federal Democratic Republic of Ethiopia, JICA, 2012
4 http://www.iwmi.cgiar.org/assessment/files/pdf/publications/WorkingPapers/WaterofAwasBasin.pdf
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