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Afghanistan Dehsabz South Groundwater Survey
JICA 5-1 DCDA
CHAPTER 5 GROUNDWATER DEVELOPMENT In the previous Chapters, all
the field work results were described. In this Chapter, groundwater
development potential is to be estimated roughly from a recharging
potential based upon the existing hydrogeological data/information,
field work results and examinations thereof. Given the basic
purpose of this Sub-project, groundwater development potential in
each site is to be estimated, and then the development potential
will be examined in detail using MODFLOW simulation model only for
the site(s) having promising high potential on the future
development. Groundwater development scenarios are then examined,
following which a conceptual development design will be formulated.
A monitoring system on the groundwater table in the target sites
will also be presented.
5.1 Estimation on Groundwater Development Potentials
Groundwater is one of the renewable natural resources, whereby
we can develop it in a sustainable way if we keep exploiting
groundwater within the volume it renews every year. Renewing
groundwater volume in a certain groundwater basin takes place
mostly by precipitation, which is called as “Perennial Yield” of
the basin. Though renewing of the groundwater volume varies
depending upon the annual precipitation, the sustainable
groundwater development potential therefore settles almost same as
the average perennial yield of the groundwater basin.
This Sub-project tries to estimate the average perennial yield
of each target groundwater basin as a sustainable1 development
potential roughly as the first step. The perennial yield of a
groundwater basin shall be estimated through examinations on the
direct groundwater recharge by precipitation in a certain
groundwater basin and the indirect recharge by seepage from
river-bed or canal bottom passing through the target basin. The
precipitation data available in and around the survey area are only
the observation records at the Kabul Airport. Based on the
observation at the Airport, average annual precipitation for the
current six years was found at around 303 mm/year (see Figure
5.1.1).
Exactly saying, groundwater development potential is not equal
to the perennial yield since it must take existing groundwater
usage in the groundwater basin into consideration. It follows that
the groundwater development potential in a certain groundwater
basin is “the perennial yield minus the existing level of
groundwater exploitation”. The existing groundwater exploitation,
current groundwater usage in other words, is difficult to exactly
grasp on quantitative basis.
However, most of the existing groundwater usages are observed on
domestic water use, periodical irrigation use for a period of
roughly 3 months in a year, and also some industrial use especially
for brick factories at the Bakhtyaran site and Daneshmand-Pymonar
site. The current use of groundwater
1“Short-term Development Potential” may be referred to as the
groundwater development volume we expect to be allowed to exploit,
beyond the sustainable development volume, only for short period
such as three or four years. However, there is no such allowable
groundwater development volume which can be exploitable beyond the
perennial yield, nor such term of Short-term Development Potential
hydro-geologically. Continuous over exploitation beyond the
perennial yield causes rapid groundwater depletion and finally
dries up or destroys the aquifer. No one knows a certain aquifer
once destroyed can recover or not. With this in mind, this
Sub-project is to examine the sustainable amount of groundwater
development.
193
292
386
279
165
504
0
100
200
300
400
500
600
2004 2005 2006 2007 2008 2009
Ann
ual P
reci
pita
tion,
mm
Figure 5.1.1 Annual Precipitation from 2004 - 2009
Average: 303 mm/year
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Dehsabz South Groundwater Survey Afghanistan
DCDA 5-2 JICA
might be compensated from the groundwater development system to
be constructed, except for the Tangi Kalay site which already has
large scale production wells owned by an investor. Following
discussion centers on the maximum perennial yield in each target
site while current water usage is discussed in the following
sub-chapter:
5.1.1 Development Potential in Site-1 (Tangi Kalay)
In Site-1 (Tangi Kalay area), there are large scale production
wells already along with the north bank of the Kabul River.
Therefore, it is unlikely that there is chance to develop
groundwater furthermore. In the site, taking this condition into
account, only groundwater quality analysis on the existing
production well was conducted. No other hydrogeological
investigation works such as geophysical prospecting and test well
drilling have been conducted. The groundwater development potential
is therefore roughly estimated based on the existing data and
information.
1) Direct recharging
The north bank of the Kabul River has its own catchment area in
its further north of around 19.5 km2
(see Figure 5.1.2). The infiltration ratio in this catchment
area can be evaluated at 0.06 to 0.082 because the catchment area
is composed of relatively course materials due to its rather high
average inclination. Thus, the direct recharging through the own
catchment area is calculated as:
19.5(km2) x 106 x 0.303(m) x 0.06 - 0.08 = 354,510 - 472,680
m3/year. ....................................(a)
2) Indirect recharging
In the Tangi Kalay area, Kabul River is passing through around
5km before it enters the steep and narrow gorge. The area is
located at the low end of the Kabul Basin, and therefore results of
a previous groundwater study on the Kabul basin; “Study on
Groundwater Resources Potential in the Kabul Basin (2011)”
conducted by JICA, can be applied. In accordance with the study,
the low end of the Kabul River is recharging groundwater through
seepage from the bottom by around 0.322 MCM/km/year. Based on the
data, the groundwater recharge through the river is estimated
as:
5.0 (km) x 0.322 (MCM/km/year) x 1,000,000 = 1,610,000 m3/year
........................................ (b)
3) Groundwater development potential
Groundwater development potential, thus calculated, shall be
added together and resulted as (a) + (b);
354,510 + 1,610,000 ≒ 1,964,500 m3/year
2 Under the Study on Groundwater Resources Potential in the
Kabul Basin, simulations were carried out dividing the target Kabul
Basin into more than 130 sub-basins wherein infiltration ratio and
coefficient of permeability were so evaluated as to meet the field
observation results of groundwater tables. In so doing, 10%, 7% (or
0.06 – 0.08), 5% (or 0.04 – 0.06), and 3% (or 0.02 – 0.04) were
identified as the infiltration ratios of area with high
infiltration rate, e.g. fan or talus, area covered by coarse
materials with rather high ground inclination, area of normal
alluvial plain in the Kabul Basin, and area covered by fine
materials e.g. silt or silty clay respectively.
Catchment Boundary
Tangi Kalay
Pol-e Charkhi Figure 5.1.2 Catchment area of Tangi Kalay
Area
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Afghanistan Dehsabz South Groundwater Survey
JICA 5-3 DCDA
≒ 5,380 m3/day ≒ 62 liter/sec
472,680 + 1,610,000 ≒ 2,082,680 m3/year ≒ 5,700 m3/day ≒ 66
liter/sec
Groundwater development potential in the site is roughly
estimated as from 5,300 to around 5,700 m3/day. It is rather
excellent potential but it may have more development potential
because the area can be recharged from its southern bank too. As
evidence, production wells for irrigation purpose existing in the
north bank of the Kabul River can yield around 45 to 40 liter/sec
with 6.0m drawdown.
5.1.2 Development Potential in Site-2 (Pol-e Charkhi)
At the site-2, Pol-e Charkhi area, one of the tributaries of the
Kabul River, named “Buthkhak River” joins together. The Buthkhak
River has a large catchment area of some hundreds sq.km but the
catchment which can replenish the groundwater is confined at its
lower middle stream (at the east of Atal Ghar) by a natural
underground dam3. Direct recharging by precipitation can therefore
be expected from only the downstream catchment area from the
natural underground dam point. Even though it is less than 1/4 of
the total catchment, the available Buthkhak catchment area comes to
around 66.5 km2 (see Figure 5.1.3).
1) Direct recharging
As explained in the previous section, a yearly average
precipitation observed at Kabul Airport in current 6 years is 0.303
m/year. An infiltration ratio of precipitation in the Buthkhak
River basin is, however, not so high as the northern catchment of
Tangi Kalay because the catchment area is mostly flat and covered
by fine materials such as silty soil. In this area, infiltration
rate from 0.04 to 0.06, which is almost average infiltration ratio
of Alluvial deposits in Kabul Basin, shall be adopted. Thus, direct
recharge in this area is;
66.5 (km2) x 106 x 0.303 (m) x 0.04 - 0.06 = 805,980 - 1,208,970
m3/year ................................(c)
3 At this point of the Buthkhak River, hard foundation which has
very low permeability comes up preventing the groundwater flow from
upstream to downstream or simply saying such very low permeable
foundation forms a natural underground storage in its upstream
side, which is called underground dam. With this condition at the
midpoint of Buthkhak River, only downstream area is counted as the
catchment area which can replenish the groundwater of the Pol-e
Charkhi area.
Figure 5.1.3 Catchment Area of Pol-e Charkhi Area
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Dehsabz South Groundwater Survey Afghanistan
DCDA 5-4 JICA
2) Indirect recharging
In this area, the Kabul River runs through around 3.0km length.
As mentioned above, the Kabul River recharges groundwater through
seepage at around the rate of 0.322 MCM/km/year. With the rate, the
site can be recharged through the Kabul River as:
3.0 (km) x 0.322 (MCM/km/year) x 1,000,000 = 966,000
m3/year.................................... (d)
3) Groundwater development potential
Groundwater development potential in Pol-e Charkhi area is now
estimated by adding (c) and (d);
805,980 + 966,000 ≒ 1,771,980 m3/year ≒ 4,850 m3/day ≒ 56.2
liter/sec
1,208,970 + 966,000 ≒ 2,174,970 m3/year ≒ 5,960 m3/day ≒ 69.0
liter/sec
Thus, groundwater development potential in this site is roughly
estimated from 4,850 to 5,960 m3/day, nearly same as the potential
of Tangi Kalay area. It shows also excellent development potential.
In addition, the site may have an extra recharging through an old
river route of the Logar River which was to join the Kabul River at
Pol-e Charkhi area for some period in an ancient time. The effect
of the old Logar is, however, not taken into consideration because
AUWSSC and KfW are planning to develop groundwater in the lower
Logar sub-basin, just upstream of the old river route.
5.1.3 Development Potential in Site-3 (Bakhtyaran)
Bakhtyaran site lies in the Dehsabz Basin and there is no major
river. Only a Bakhtyaran canal is passing through along the western
edge of the target site. Rather small but Bakhtyaran site also has
a catchment area in it eastern side. The site can be recharged by
precipitation and also by the Bakhtyaran canal, though the recharge
from the canal may not be so noticeable.
1) Direct recharging
Catchment area of Bakhtyaran site extends toward east to the
Mount Gharib Ghar. The mountain is of the watershed at its eastern
side and the catchment is enclosed by the Bakhtyaran canal at its
western side. Catchment area of the site is estimated at only 16.0
km2 (see Figure 5.1.4). The area near the site where groundwater
development is planned is widely covered by worked Loess, which is
composed of very fine materials such as clay or silt, and the
infiltration ratio of rain in this area is estimated at 0.02 to
0.04. Thus, the direct recharging by precipitation in this site is
as small as:
Figure 5.1.4 Catchment Area of Bakhtyaran Area
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Afghanistan Dehsabz South Groundwater Survey
JICA 5-5 DCDA
16.0 x 106 x 0.303 x 0.02 - 0.04 = 96,960 - 193,920
m3/year......................................................(e)
2) Indirect recharging
Bakhtyaran canal, passing through along the western edge of the
site for around 3.0 km, is not perennial and the averaged flow rate
is very small. The previous study on the Kabul Basin, Groundwater
Resources Potential in the Kabul Basin, 2011, surveyed the flow
sourced from Kabul River. The average yearly runoff of the canal
was around 7.7 MCM/year, and this is only less than 2.0% the runoff
of the Kabul River at Pol-e-Charkhi point. The condition of the
canal bottom is also different from that of Kabul River, less
permeable than that of Kabul River. Taking those into account,
indirect recharging rate of the canal is set at only 1% of that of
Kabul River:
3.0 (km) x 0.322 (MCM/km/year) x 1,000,000 x 0.01 = 9,660
m3/year ..................................... (f)
3) Groundwater development potential
Groundwater development potential in Bakhtyaran area shall be
estimated by adding (e) and (f);
96,960 + 9,660 ≒ 106,620 m3/year ≒ 292 m3/day ≒ 3.4
liter/sec
193,920 + 9,660 ≒ 203,580 m3/year ≒ 558 m3/day ≒ 6.5
liter/sec
There is an observation relating to the above potential. An
observation well by AGS exists near the Bakhtyaran site. Yearly
fluctuation of the groundwater table in the observation well is
around 3.0m in average. When the area of target site is estimated
at 1.8 km2 (3.0 km x 0.6 km) and effective porosity of the aquifer
at 0.03, the volume of renewable groundwater can be estimated as
follows, indicating quite similar calculation results:
1.8 (km2) x 1,000,000 x 3.0 (m) x 0.03 = 162,000 m3/year ≒ 434
m3/day ≒ 5.1 liter/sec
As aforementioned, estimated groundwater development potential
in Bakhtyaran site is very low as only several hundreds cubic meter
per day. When considering the water demand in the new Dehsabz city,
it may be concluded that there seems little groundwater development
potential in Bakhtyaran site.
5.1.4 Development Potential in Site-4 (Pymonar - Daneshmand)
Daneshmand site is located in a quite flat plain in between
Pymonar village and Daneshmand village. Some small drainages are
passing through the plain forming gullies from the west to the
east. There is neither perennial river in this area nor canal.
Therefore, resources of the groundwater here is only
precipitation.
1) Direct recharging
The area is widely covered by worked Loess on its ground
surface, making difficult to infiltrate rain water into the ground.
Infiltrate ratio in this area is set at less than 0.03 as the
maximum estimation. The target site is confined at its western side
by low mountain range separating the Dehsabz basin from the Parwan
basin. Total catchment area of this site is estimated at 53.0 km2
(see Figure 5.1.5), and thus direct recharging by rainfall is
calculated as:
53.0 (km2) x 106 x 0.303 (m/year) x 0.03 = 481,770 m3/year
............................................. (g)
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Dehsabz South Groundwater Survey Afghanistan
DCDA 5-6 JICA
2) Indirect recharging
Indirect recharge through river or canal does not exist in this
site.
3) Groundwater development potential
Thus, the total groundwater recharging amount estimated for the
area is 481,770 m3/year, which is converted into 1,320 m3/day and
15.3 liter/sec.
Though the estimated groundwater development potential in
Pymonar - Daneshmand site is much better than Bakhtyaran site,
there is still not enough recharging to develop at a certain scale.
Farther, groundwater quality analysis also identified that the
water quality was no good showing very high EC value and high Mn
contents. Thus, groundwater development in this area located
between Pymonar village and Daneshmand village will hardly be
possible.
5.1.5 Summary of the Development Potential
As discussed so far, the averaged perennial yield in each target
site varied from only 425 m3/day to more than 5,000 m3/day.
Groundwater development potential in the two sites of Bakhtyaran
and Pymonar - Daneshmand are very small while sites along the Kabul
River show large potential thanks to the huge groundwater recharge
through the seepage from the river bottom. Sustainable groundwater
development potential in these target sites are summarized in Table
5.1.1:
Table 5.1.1 Summary of Groundwater Development Potential
Site Catchment Area, km2
Direct Recharge,
m3/Yr
Indirect Recharge,
m3/Yr
Development Potential, m3/day
Feasibility Remarks
Tangi Kalay 19.5 354,510 – 472,680 1,610,000 5,380 – 5,700(ave
5,500) Hard
Existing large yielding wells
Pol-e Charkhi 66.5 805,980 – 1,208,970 966,000 4,850 – 5,960(ave
5,400) High
High potential, not much current use
Bakhtyaran 16.0 96,960 – 193,920 9,660 292 – 558 (ave. 420)
No
Very little water, poor water quality
Daneshmand 53.0 481,770 0 1,300 No Very small water resource
available Source: JICA Sub-project Team Note: Average annual
precipitation is 303 mm.
As shown in the above table, only the sites along the Kabul
River have groundwater resources potential feasible to develop.
However, Tangi Kalay site has already large scale production wells
mainly for irrigation purpose owned by an investor. Therefore, the
Tangi Kalay site may be said not to be much feasible in terms of
development unless there is a water-trade agreement with the well
owner. On the other hand, candidate sites of Bakhtyaran and
Daneshmand-Pymonar, located in Dehsabz Basin, have a little
groundwater resources and what is worse the water quality is not so
good. It is therefore concluded that the groundwater development
potential for the 2 sites is poor.
Figure 5.1.5 Catchment Area of Daneshmand-Pymonar Area
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Afghanistan Dehsabz South Groundwater Survey
JICA 5-7 DCDA
5.2 MODFLOW Analysis on Potential Sites
As discussed so far, only Pol-e Charkhi site has high
feasibility on further groundwater development, and Tangi Kalay
site has the next feasibility depending upon the negotiation with
the investor having large scale irrigation wells. In this section,
groundwater development potential on these two sites are examined
more detail through MODFLOW simulation, whether it is feasible to
pump up the estimated development amount in these two sites.
5.2.1 MODFLOW Simulation on Pol-e Charkhi Site
(1) Concept of MODFLOW Model
Concept of MODFLOW model for Pol-e Charkhi site is shown in
Figure 5.2.1. As shown in the figure, not all of the Buthkhak River
basin was modeled but only the area underlain by Alluvial aquifer.
The cross section model was simplified by two layers structure and
the flat bottom from the northern end to the half of the total
area.
The extent of area is around 30.1 km2, and depth of the aquifer
is set from 12m to 30m below the ground surface. However, the upper
2m is already dry. Materials of aquifer are estimated as Sand and
Gravels of river-bed deposits. Southern half of the model area (the
Buthkhak river basin) is omitted
Figure 5.2.1 MODFLOW Model for Pol-e Charkhi Site
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Dehsabz South Groundwater Survey Afghanistan
DCDA 5-8 JICA
from the analysis because there is no groundwater system in its
area. Widths of the cells are set 20m at the minimum (near the New
Production Wells) and 100m in the other areas. MODFLOW model, thus
built up, is shown in ANNEX-VIII.1.
(2) Assumptions
For MODFLOW analysis, physical properties of layers consisting
of the model, boundary conditions, and hydrogeological information
on the site are required. Among them, some of hydrogeological
information was obtained through the investigation and data
collection under this Sub-project, but the other physical
properties were assumed by general practices facing the little data
availability.
Physical properties of the layers, assumed in the analysis, are
summarized in Table 5.2.1. Permeability and Specific Storativity on
the aquifer were estimated from the results of Pumping Test
conducted in the existing well in the National Radio Station
(T=3,400 m2/day, S=0.0036). The northern end of the model, which is
the Kabul River was set as fixed head boundary, and the both sides
of the Buthkhak River catchments area were set as no flow
boundaries.
Precipitation on the area is 0.303 m/year from the 6-years
average rainfall at Kabul Airport Station, and 0.05 of infiltration
rate was applied. Those measured data or assumptions were given to
the model, and four (4) wells of equivalent existing wells were
assumed to evaluate the current groundwater balance through a “try
and error trial”. The trial has changed the pumping rates from
these assumed wells in order to adjust the groundwater table near
the New Production Wells being around GL. -14m.
As a result, a current groundwater table was assumed as Figure
5.2.2. To adjust the groundwater table near the production wells,
total 1,400 m3/day of pumping from those assumed equivalent wells
were required.
Table 5.2.1 Assumed Physical Properties of Layers Particular
Sandy Clay
(GL. 0 - -12m) Aquifer
(GL. -12 – 30 m) Permeability, K (m/sec) 1.0 x 10-6 2.46 x 10-3
Specific Storativity Ss (m-1) 1.0 x 10-4 2.25 x 10-4 Specific Yield
Sy (%) 5 25 Source: JICA Sub-project Team
Figure 5.2.2 Current groundwater Balance of target Area
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Afghanistan Dehsabz South Groundwater Survey
JICA 5-9 DCDA
(3) Case Study
Two new production wells were assumed in the Radio Station at
Pol-e Charkhi site, and pumping simulations were carried out for
several cases. The cases of Pumping Simulation are summarized in
Table 5.2.2 (Results of MODFLOW simulation, estimated drawdown at
each production well by the time-series and distance, and estimated
groundwater contour maps in time series at every one year are
attached in ANNEX-VIII.2).
(4) Results of MODFLOW analysis: Groundwater Level in the
Well
Groundwater drawdown in the Buthkhak basin is relatively small
(refer to ANNEX-VIII.2); drawdown only from a few centimeters to
several tens of centimeters even near the production wells were
simulated. These small scales of drawdown may be brought about by
the influential interference of the Kabul River at the northern
edge of the simulation area.
Then, the groundwater drawdown in the production wells during
pumping was examined. The model was not dispersed enough to
reproduce the water level in the pumping well (the minimum cell
width was 20m). The water level at the just pumping well was
calculated using the following empirical equation by Anderson and
Woessner (1994):
hw = hij – Q (ln re – ln rw) / 2 πT Where hw: Water head in the
well, hij: calculated water head at the node, Q: pumping rate, re:
distance between the node and equal head point, (equal well radius)
rw: radius of the well, and T: Transmissivity. Equal well radius
was calculated as follows:
re = SQRT(⊿x⊿y/π)・E where, ⊿x, ⊿y: size of cell, E: Coefficient
in the right table, and α= MAX(⊿x/⊿y, ⊿y/⊿x)
Groundwater drawdown in the production wells (No.1 well for
eastern one, and No.2 for western one), thus calculated, are
summarized in Table 5.2.3, and shown in Figure 5.2.3. Groundwater
contour map of the site, in Case-4 (total 5,000 m3/day pumping) and
at after 5 years from the time the pumping started, is shown in
Figure 5.2.4.
Table 5.2.2 MODFLOW Case Study Case Pumping from No.1
well, m3/day Pumping from No.2
well, m3/day Total Pumping Rate, m3/day
Case-1 1,000 1,000 2,000 Case-2 1,500 1,500 3,000 Case-3 2,000
2,000 4,000 Case-4 2,500 2,500 5,000 Case-5 3,000 3,000 6,000
Source: JICA Sub-project Team
α E α E 1.1 1.002 1.5 1.041 1.2 1.008 1.6 1.077 1.3 1.017 1.7
1.118 1.4 1.028 1.8 1.204
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Dehsabz South Groundwater Survey Afghanistan
DCDA 5-10 JICA
Table 5.2.3 Groundwater Table at Production Wells in Pol-e
Charkhi Site Case.1 Case.2 Case.3 Case.4 Case.5
Q=1,000×2(m3/day) Q=1,500×2(m3/day) Q=2,000×2(m3/day)
Q=2,500×2(m3/day) Q=3,000×2(m3/day)Time
(days) No.1 No.2 No.1 No.2 No.1 No.2 No.1 No.2 No.1 No.2
0 -13.965 -13.990 -13.965 -13.990 -13.965 -13.990 -13.965
-13.990 -13.965 -13.990 1 -14.706 -14.730 -15.096 -15.120 -15.485
-15.485 -15.906 -15.931 -16.269 -16.293 3 -14.733 -14.757 -15.136
-15.161 -15.539 -15.564 -15.974 -15.999 -16.352 -16.3765 -14.746
-14.770 -15.156 -15.180 -15.565 -15.590 -16.007 -16.032 -16.390
-16.415
10 -14.764 -14.788 -15.183 -15.207 -15.602 -15.626 -16.053
-16.077 -16.446 -16.471 20 -14.785 -14.808 -15.216 -15.238 -15.646
-15.668 -16.109 -16.130 -16.514 -16.534 50 -14.818 -14.840 -15.265
-15.285 -15.713 -15.731 -16.193 -16.210 -16.616 -16.631
100 -14.843 -14.864 -15.303 -15.322 -15.763 -15.781 -16.256
-16.273 -16.692 -16.707 200 -14.866 -14.885 -15.338 -15.355 -15.810
-15.825 -16.316 -16.328 -16.764 -16.774 365 -14.884 -14.900 -15.364
-15.377 -15.846 -15.855 -16.361 -16.366 -16.820 -16.820 730 -14.900
-14.912 -15.388 -15.396 -15.879 -15.880 -16.403 -16.398 -16.870
-16.859
1,095 -14.907 -14.918 -15.399 -15.404 -15.893 -15.891 -16.421
-16.411 -16.893 -16.876 1,460 -14.911 -14.921 -15.406 -15.409
-15.903 -15.898 -16.433 -16.420 -16.907 -16.886 1,825 -14.915
-14.924 -15.412 -15.413 -15.910 -15.903 -16.442 -16.427 -16.918
-16.894
Source: JICA Sub-project Team, MODFLOW Simulation Unit: GL
-m
As shown in the table, groundwater drawdown caused by the
pumping in the production wells, from each 1,000 to 3,000 m3/day
are small, only from 81 cm to 2.45 m at the longest period (5
years) in Case-1 to Case-5.
Supposedly, they may be also due to the influence by constant
recharge from the Kabul River. The maximum drawdown of 2.05 m from
the original groundwater table in Case-4, which is the estimated
groundwater potential in the site, is enough small comparing to the
thickness of the aquifer which is around 16m (less than 13%), and
it suggests that the pumping up of total 5,000 m3/day of
groundwater through two production wells in this site shall be
feasible.
Production Well No.1
-17.000
-16.500
-16.000
-15.500
-15.000
-14.500
-14.000
0 500 1000 1500 2000
Time after pumping started (day)
G.W
Tab
le G
L.(m
)
Case.1
Case.2Case.3Case.4Case.5
Figure 5.2.3 (1) Changing of Groundwater Table at the Production
Well No.1
Production Well No.2
-17.000
-16.500
-16.000
-15.500
-15.000
-14.500
-14.000
0 500 1000 1500 2000
Time after Pumping started (day)
G.W
Tab
le G
L.(m
)
Case.1Case.2Case.3Case.4Case.5
Figure 5.2.3 (2) Changing of Groundwater Table at the Production
Well No.2
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Afghanistan Dehsabz South Groundwater Survey
JICA 5-11 DCDA
(5) Results of MODFLOW analysis: Groundwater Drawdown in the
Village
Aforementioned section estimated the groundwater level in the
well. MODFLOW simulation gives not only the groundwater level in
the well but also all the groundwater levels at each nodal point of
the model. Table 5.2.4 summarizes the groundwater drawdown with
total 5,000 m3/day pumping (Case 4) by location such as 30 m away
from the well, 100m, 200, etc. to 5 km away and by time such as 1
day, 10 days, 100 days, 200 days, 1 year, etc, to 5 years later. At
a glance of the table is that the drawdown is not so much as
exampled in the level at the time of 5 years after the pumping
started, which is only 0.739 meter even at the 30 m from the well.
If the location is 5 km far from the well, the drawdown becomes
only 0.241 m.
Table 5.2.4 Groundwater Drawdown at Different Location by Time,
Case 4: 2,500 m3/day x 2 wells Days 30m 100m 200m 300m 400m 500m
1km 2km 3km 5km
X-coord. (m) 2,090 2,130 2,170 2,220 2,300 2,380 2,700 2,900
3,500 4,300 Y-coordi.(m) 12,730 12,670 12,580 12,500 12,420 12,350
11,900 11,300 10,500 8,500
1 -0.208 -0.073 -0.021 -0.006 -0.001 -0.000 0.000 -0.000 -0.000
0.000 3 -0.274 -0.132 -0.062 -0.031 -0.013 -0.006 -0.000 -0.000
-0.000 0.000 5 -0.306 -0.162 -0.088 -0.051 -0.027 -0.014 -0.000
-0.000 -0.000 0.000
10 -0.351 -0.205 -0.127 -0.086 -0.055 -0.036 -0.003 -0.000
-0.000 0.000 20 -0.406 -0.258 -0.177 -0.132 -0.096 -0.071 -0.014
-0.002 -0.000 0.000 50 -0.489 -0.341 -0.259 -0.212 -0.172 -0.143
-0.057 -0.019 -0.002 0.000
100 -0.552 -0.406 -0.326 -0.280 -0.241 -0.212 -0.117 -0.059
-0.016 0.000 200 -0.612 -0.468 -0.392 -0.349 -0.313 -0.286 -0.195
-0.129 -0.060 -0.006
365 (1 yr) -0.658 -0.516 -0.444 -0.405 -0.372 -0.348 -0.268
-0.205 -0.125 -0.030730 (2 yrs) -0.699 -0.560 -0.492 -0.456 -0.427
-0.406 -0.341 -0.288 -0.212 -0.093
1,095 (3 yrs) -0.718 -0.580 -0.514 -0.480 -0.452 -0.434 -0.377
-0.332 -0.264 -0.1491,460 (4 yrs) -0.730 -0.593 -0.528 -0.495
-0.469 -0.451 -0.401 -0.361 -0.301 -0.1991,825 (5 yrs) -0.739
-0.603 -0.539 -0.507 -0.481 -0.465 -0.419 -0.384 -0.332 -0.241
Source: JICA Sub-project Team, by MODFLOW simulation Unit: m
Groundawter Contour Drawdown Contour
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
5 Years After
0 2000 4000 6000 8000 100000
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000Kabul River : GL.-14m
Well Point : No.1
Well Point : No.2
Pol-e Charkhi Case.4: Q=5,000m3/s (No.1+No.2)
5 Years After
0 2000 4000 6000 8000 100000
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000Kabul River : GL.-14m
Well Point : No.1
Well Point : No.2
Pol-e Charkhi Case.4 : Q=5,000m3/s (No.1+No.2)
Figure 5.2.4 Estimated Groundwater Contour at Pol-e Charkhi
Site, Case-4, after 5 years
-
Dehsabz South Groundwater Survey Afghanistan
DCDA 5-12 JICA
5.2.2 MODFLOW Simulation on Tangi Kalay Site
(1) Concept of MODFLOW Model
Concept of MODFLOW model on Tangi Kalay site is shown in Figure
5.2.5. As shown in the figure, all of the northern catchments area
of this site (19.5 km2) was fully modeled but its upstream zone was
reduced to
the depth of aquifer, from the full depth of 42m to the upstream
end, as shown in the cross section model. The cross section was
built up from Lithological log of Mr. Omarzay’s Well No.1 shown as
Figure 5.2.6. Southern edge of the model is the Kabul River as a
fixed head boundary and the other sides are set as no flow
boundary.
(2) Assumptions
Aquifer structure in this site was simply modeled as one layer
structure. Physical properties on the aquifer, applied in the
simulation, are the same as the ones for Pol-e Charkhi site (see
Table 5.2.5). To estimate the current groundwater balance, current
recharging and discharging were firstly evaluated.
For recharging, a yearly average precipitation was set at 0.303m
same as that of Pol-e Charkhi site, but an infiltration ratio was
assumed as 0.07 in this site. Then, the Kabul River was set as
fixed head boundary. For discharge, two equivalent wells with each
1,014 m3/day of pumping rate were assumed at near around the Kabul
River. Thus, the current groundwater balance (Groundwater Contour
Map) was simulated as shown in Figure 5.2.7. As shown in the
figure, the current groundwater table near the new production well
was around 5.0m below the ground surface.
(3) Case Study
A new production well was assumed at near the Kabul River, in
between the two equivalent assumed wells. MODFLOW simulation was
conducted as case study changing the pumping rates of 1,500, 2,000,
2,500, and 3,000 m3/day, at an interval of 500 m3/day.
Table 5.2.5 Assumed Physical Properties Particular Aquifer
(GL. -5 – 42 m) Permeability, K (m/sec) 2.46 x 10-3 Specific
Storativity Ss (m-1) 2.25 x 10-4 Specific Yield Sy (%) 25 Source:
JICA Sub-project Team
Figure 5.2.5 MODFLOW Model on Tangi Kalay
Figure 5.2.6 Mr. Omarzay’s Well
-
Afghanistan Dehsabz South Groundwater Survey
JICA 5-13 DCDA
(4) Results of MODFLOW analysis
Results of MODFLOW analysis are attached in ANNEX-VIII.3. Only
one results of the case on 3,000 m3/day of discharge rate, 5 years
after the pumping had started, is shown in Figure 5.2.8. As easily
readable from the figure, groundwater drawdown in the site, Tangi
Kalay northern catchments area, is very small as only some
centimeters in the nearest simulation cell to the production
well.
In this site too, groundwater drawdown at the production well
itself was estimated. As explained in previous section (Chapter
5.2.1 (3)), the model dispersion is not enough small to reproduce
the water level in the pumping well (the minimum cell width was
20m). The water level at the pumping well was calculated using the
equation by Anderson and Woessner (1994). Estimated groundwater
drawdown in the new production well, in time sequence and discharge
amounts, are shown in Table 5.2.6.
As shown in the table, the maximum drawdown in the production
well is, even in the Case-4 (the maximum discharge of 3,000
m3/day), less than 1.4m which does not cause any problem for
discharging groundwater in this site because the drawdown is only
3.5% of the aquifer thickness. Thus, the groundwater development
potential in Tangi Kalay site shall be at least 3,000 m3/day on
condition that the investor’s two wells are in operation as
designed. Groundwater isobathic map on Tangi Kalay site at 5 years
after the pumping started in Case-4 is shown in Figure 5.2.8.
Table 5.2.6 Groundwater Level in New Production Well in Tangi
Kalay Case 1 Case 2 Case 3 Case 4 Days after
Pumping Q=1,500(m3/day) Q=2,000(m3/day) Q=2,500(m3/day)
Q=3,000(m3/day) Remarks
0 -5.002 -5.002 -5.002 -5.002 1 -5.602 -5.814 -6.027 -6.239 3
-5.618 -5.835 -6.053 -6.271 5 -5.624 -5.843 -6.062 -6.282
10 -5.629 -5.849 -6.071 -6.292 20 -5.632 -5.853 -6.076 -6.298 50
-5.635 -5.858 -6.081 -6.305
100 -5.637 -5.861 -6.085 -6.309 200 -5.639 -5.863 -6.087 -6.312
365 -5.640 -5.864 -6.089 -6.314 730 -5.640 -5.864 -6.090 -6.315
1,095 -5.641 -5.865 -6.090 -6.316 1,460 -5.641 -5.865 -6.091
-6.316 1,825 -5.641 -5.865 -6.091 -6.317
Source: JICA Sub-project Team, MODFLOW simulation Unit: GL
-m
Figure 5.2.7 Current Groundwater Contour Map
-
Dehsabz South Groundwater Survey Afghanistan
DCDA 5-14 JICA
(5) Results of MODFLOW analysis: Groundwater Drawdown in the
Village
In addition to the groundwater level in the well, MODFLOW
analysis estimated the groundwater levels at all the nodal point.
Table 5.2.7 summarizes the groundwater drawdown with 3,000 m3/day
pumping (Case 4) by location and by time up to 5 km away from the
well. The table shows the drawdown is not so much as exampled in
the water level at the time of 5 years after the pumping started,
which is only 0.205 meter even at the 30 m from the well. If the
location is 5 km far from the well, the drawdown becomes only 0.047
m.
Table 5.2.7 Groundwater Drawdown at Different Location by Time,
Case 4: 2,500 m3/day x 2 wells Days 30m 100m 200m 300m 400m 500m
1km 2km 3km 5km
X-coord. (m) 1,530 1,475 1,475 1,550 1,550 1,550 1,675 2,450
3,350 5,250Y-coordi.(m) 670 725 825 950 1,050 1,150 1,650 2,450
3,050 4,050
1 -0.130 -0.056 -0.027 -0.010 -0.004 -0.002 -0.000 -0.000 -0.000
-0.0003 -0.161 -0.086 -0.054 -0.030 -0.019 -0.011 -0.001 -0.000
-0.000 -0.0005 -0.172 -0.097 -0.065 -0.041 -0.028 -0.019 -0.002
-0.000 -0.000 -0.000
10 -0.181 -0.107 -0.077 -0.053 -0.039 -0.030 -0.008 -0.000
-0.000 -0.00020 -0.187 -0.115 -0.085 -0.061 -0.048 -0.039 -0.015
-0.002 -0.000 -0.00050 -0.194 -0.122 -0.093 -0.070 -0.059 -0.050
-0.027 -0.008 -0.002 -0.000
100 -0.198 -0.127 -0.099 -0.077 -0.066 -0.058 -0.037 -0.017
-0.007 -0.001200 -0.201 -0.131 -0.103 -0.081 -0.071 -0.064 -0.044
-0.026 -0.016 -0.006
365 (1 yr) -0.202 -0.132 -0.105 -0.084 -0.074 -0.067 -0.049
-0.033 -0.024 -0.015730 (2 yrs) -0.203 -0.134 -0.107 -0.086 -0.076
-0.070 -0.053 -0.041 -0.035 -0.029
1,095 (3 yrs) -0.204 -0.135 -0.108 -0.087 -0.078 -0.071 -0.056
-0.045 -0.041 -0.0381,460 (4 yrs) -0.204 -0.135 -0.109 -0.088
-0.079 -0.072 -0.057 -0.048 -0.046 -0.043
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
6500 70000
1000
2000
3000
4000
5000
6000
Kabul River : GL.-5m
Well Point : No.1
Figure 5.2.8 Groundwater Isobathic Map in Tangi Kalay (Case-4, 5
years after)
-
Afghanistan Dehsabz South Groundwater Survey
JICA 5-15 DCDA
Days 30m 100m 200m 300m 400m 500m 1km 2km 3km 5km 1,825 (5 yrs)
-0.205 -0.136 -0.109 -0.089 -0.079 -0.073 -0.058 -0.050 -0.048
-0.047
Source: JICA Sub-project Team, by MODFLOW simulation unit: m
5.2.3 Summary on MODFLOW Analysis
MODFLOW Analysis was conducted for the two candidate sites of
Pol-e Charkhi and Tangi Kalay. In both sites, physical properties
were assumed in Table 5.2.8.
Table 5.2.8 Assumptions on Physical Properties Property Aquifer
Surface Cover
Permeability k (m/sec) 2.46 x 10-3 1.0 x 10-6 Specific
Storativity Ss (m-1) 2.25 x 10-4 1.0 x 10-4 Specific Yield Sy (%)
25 5 Catchments Area (km2) Pol-e Charkhi 0.08 Tangi Kalay: 19.5
Infiltration Ratio (%) Pol-e Charkhi: 0.05 Tangi Kalay: 0.07
Source: JICA Sub-project Team
Model was built up in 20 to 100m disperse, 20m cells near around
the production wells (refer to Figure 5.2.9 for Pol-e Charkhi
area). Two new production wells in Pol-e Charkhi and a new
production well in Tangi Kalay sites were set near the Kabul River.
The Kabul River in both sites was set as a fixed head boundary and
the other sides were set as a no flow boundary. Current groundwater
balance was estimated to adjust the groundwater table to the
observed levels of around -14m in Pol-e Charkhi and -5m in Tangi
Kalay site.
Simulation was carried out as Case Study; changing the discharge
amount and estimating the groundwater drawdown in the target area,
and the drawdown in the production wells (pumping wells) was
estimated through the equation by Anderson and Woessner (1994)
because the minimum cells are not enough fine to estimate the
drawdown in the well.
As a result, the groundwater drawdown in the new production
wells in Case-4 (discharge amount:
Figure 5.2.9 MODFLOW Model on Pol-e Charkhi Site
-
Dehsabz South Groundwater Survey Afghanistan
DCDA 5-16 JICA
2,500 m3/day/well totaling 5,000 m3/day in Pol-e Charkhi and
3,000 m3/day in Tangi Kalay) at the longest period (after 5 years
since the pumping started) was estimated at only around 2.04m and
only 1.3m in each site, respectively. The extent of drawdown is
small comparing to the aquifer thickness4 in both sites: sharing
12.7% and 3.5% of the thickness of the aquifer in the respective
sites of Pol-e Charkhi and Tangi Kalay. This means 2,500 - 3,000
m3/day/well of groundwater discharge is quite feasible. On top of
this, the groundwater development at the maximum potential
estimated by simple balance calculation on recharging, around 5,400
and 5,500 m3/day in the sites of Pol-e Charkhi and Tangi Kalay, are
also feasible.
5.3 Development Scenarios of the Groundwater Potential
Discussions so far made have identified the groundwater
potential by site based on simplified balance calculation referring
to hydrogeological characteristics studied and the results of the
pumping test. This sub-chapter explores development scenarios of
the groundwater potentials; namely how the groundwater development
should be explored in order to meet the population’s demand for the
new city of Kabul. Discussions below start with how much water the
new city will require based on the projected population and the
water demand per capita, and then the scenarios or alternatives are
to be presented in order to meet the urban water requirement by the
groundwater.
5.3.1 Water Requirement
During the discussions on the Inception Report, DCDA clarified
its stance in terms of the scale of the groundwater development as
stipulated in the Minutes of the Meetings on the ICR:
DCDA stated that the groundwater to be surveyed under the
Sub-project should target not only the Parcel-1 - Phase I area but
also the Phase I development area of Dehsabz South, covering till
the year 2015. DCDA further stressed that the Phase I development
is planned to accommodate 400,000 population with stage-wise
incremental unit water requirement, whereby the groundwater
development should be targeted according to the scale of
development.
Per-capita-water requirement has not been specified so far, but
there may be an understanding that the requirement ranges from 25
liters per capita per day as the smallest case to as much as 150
liters per capita per day according to the development stage.
Taking the per-capita requirement into account together with the
step-wise population increase to the maximum 400,000, the total
water requirement per day is resulted as shown in Table 5.3.1 and
Figure 5.3.1.
Table 5.3.1 and Figure 5.3.1, as examples, simply indicate that
population 400,000 will require a total 10,000 m3/day under the
per-capita requirement of 25 liters per day per capita while the
same population will require as much as 60,000 m3/day with the
highest water requirement of 150 liters per 4 Usually it was said
that the drawdown up to 1/4 (around 25%) of the aquifer thickness
was allowable as a safe discharge not to harm the aquifer.
0
10,000
20,000
30,000
40,000
50,000
60,000
50,00
0
100,0
00
150,0
00
200,0
00
250,0
00
300,0
00
350,0
00
400,0
00
Population
Wat
er R
equi
red,
CU
M/D
ay
25 l/day/capita
50 l/day/capita
90 l/day/capita120 l/day/capita
150 l/day/capita
Figure 5.3.1 Water Requirement by Different Per-capita Water
Requirement and Population
-
Afghanistan Dehsabz South Groundwater Survey
JICA 5-17 DCDA
day per capita. On the other hand, if population of only 150,000
is projected by the time, the requirement will be 3,750 m3/day and
22,500 m3/day, respectively.
Table 5.3.1 Water Requirement by Different Per-capita Water
Requirement and Population, m3/day Population 25 l/day/capita 50
l/day/capita 90 l/day/capita 120 l/day/capita 150 l/day/capita
50,000 1,250 2,500 4,500 6,000 7,500 100,000 2,500 5,000 9,000
12,000 15,000 150,000 3,750 7,500 13,500 18,000 22,500 200,000
5,000 10,000 18,000 24,000 30,000 250,000 6,250 12,500 22,500
30,000 37,500 300,000 7,500 15,000 27,000 36,000 45,000 350,000
8,750 17,500 31,500 42,000 52,500 400,000 10,000 20,000 36,000
48,000 60,000
Source: JICA Sub-project Team
5.3.2 Exploitable Groundwater Potential
“Chapter 5.1 Groundwater Development Potentials” explored the
groundwater potential by site as once again summarized in Table
5.3.2. In addition, the table indicates the current use of the
groundwater such as domestic use for the population, irrigation,
and also brick making factories. To estimate the current use of the
groundwater, following were assumed with reference to the inventory
survey and also interview results:
1) To estimate newly exploitable amount of groundwater, current
use of groundwater should be taken into account. These are; 1)
domestic use mainly composed of drinking and laundry, 2)
irrigation, and 3) brick factories’ use to mold bricks.
2) For the domestic use of water, mainly drinking and laundry
water, per-capita requirement per day is set at 50 liters per
capita per day while the population refers to the bigger number,
either the estimated population based on number of households given
by CSO or what was reported by the village representatives. Not all
the residential areas are to be affected by the future groundwater
development, e.g. almost half the Pol-e Charkhi area is segregated
by different catchment, only small parts of Bakhtyaran site and
Pymonar site are to be affected since the residential areas are far
from the groundwater development area. Daneshmand area is
replenished by a stream coming from upstream whereby no effect is
foreseen.
3) Concerning irrigation by groundwater, irrigation wells are
found in Pol-e Charkhi area, Pymonar area and Daneshmand area,
numbers of which are 14, 22 and 30 respectively. These wells are
operated during spring season mostly from May – July. According to
the inventory survey, an average of 40 m3/day/well can be taken as
the irrigation use for a well, converted in throughout the year
pumping discharge as per day.
4) There are brick factories in Bakhtyaran area and the area
between Pymonar village and Daneshmand village. To mold bricks,
they use groundwater ranging mostly from 40 to as much as 150
m3/day for the period of half a year to throughout the year.
Converting them into the throughout-year discharge, 48 m3/day/well
and 52 m3/day/well are employed as the unit use by the brick
factories in Bakhtyaran and Pymonar-Daneshmand area,
respectively.
5) There are three large-discharge wells in Tangi Kalay owned by
an investor. The discharges are reported at 45, 40 and 40 liters
per day per well and one of the three wells is taken as emergency
whereby two wells work in full operation during spring season, say
3 months, for irrigation purpose. Converting the 3 months discharge
of the 2 wells, 45 liters plus 40 liters, into discharge throughout
the year, an amount of 1,836 m3/day is estimated as the private
investor’s water use.
-
Dehsabz South Groundwater Survey Afghanistan
DCDA 5-18 JICA
Following table shows, after subtracting current use of
groundwater, that there are still exploitable potentials in Tangi
Kalay and Pol-e Charkhi areas but not in Bakhtyaran and
Pymonar-Daneshmand areas. For the latter 2 areas, the estimated
total amount of current use indicates an already over-exploited
situation, and therefore no further development would be
foreseen.
Table 5.3.2 Groundwater Potential in Comparison with Current Use
Site Tangi Kalay Pol-e Charkhi Bakhtyaran Pymonar Daneshmand
Total
Gross Potential, m3/day 5,500 5,400 420 1,300 Average Current
Use, m3/day 2,028 228 459 989 296 Max. Compensation % of
to-be-affected area 100 50 30 40 0 Population 3,840 3,590 5,000
4,800 4,800
Assumed by MODFLOW
simulation results.
Domestic Use, m3/day 192 90 75 96 0 50 l/day/capita No. of
Irrigation well 0 14 0 22 30 Irrigation Use, m3/day 0 138 0 217 296
40 m3/day/3months/well No. of brick factories 0 0 8 13 0 Brick
Factory Use, m3/day 0 0 384 676 0 48-52 m3/d/fac. (thr. Yr) Private
investor’s well, m3/day 1,836 - - - - (45+40) l/s/2 wells/3 m
Net Exploitable Pot’l, m3/day 3,472 Say 3,000 5,172
Say 5,000 -39 -15
Source: JICA Sub-project Team
In Tangi Kalay area, gross potential can be 5,500 m3/day while
total amount of current use is estimated at 2,028 m3/day leaving
net exploitable potential at about 3,000 m3/day. In fact, this
exploitable amount is very much dependent on what extent the
private investor is going to use his wells. In fact, should all the
3 wells owned by the investor be fully operational throughout the
year, the total discharge would be 10,800 m3/day ((45+40+40) x
86,400/1,000), overweighing the gross potential by far. On the
contrary, should the investor be willing to provide the water to
the new City under a water trade-agreement, DCDA would be able to
exploit as much as about 5,300 m3/day (5,500 – 192).
Therefore, in this Tangi Kalay site, negotiation between DCDA
and the investor is recommend as the first stage towards concluding
in an agreement whereby the water right owned by the investor can
be traded to DCDA. Otherwise, the net exploitable potential of only
about 3,000 m3/day may remain in the Tangi Kalay.
Pol-e Charkhi site shows the most promising exploitable
potential amongst 4 sites. The net exploitable potential amounts at
about 5,000 m3/day after subtracting domestic water (90 m3/day) and
irrigation water (138 m3/day). Adding the exploitable potential at
Tangi Kalay site, the total exploitable potential comes to about
8,000 m3/day, and should the agreement with the investor be made
thereby DCDA could utilize his water right, the exploitable
potential could
0
5,000
10,000
15,000
20,000
25,000
50,00
0
100,0
00
150,0
00
200,0
00
250,0
00
300,0
00
350,0
00
400,0
00
Population
Wat
er R
equi
red,
CU
M/D
ay
25 l/day /capita 50 l/day /capita90 l/day /capita 120 l/day
/capita150 l/day /capita 5,000 cum/day8,000 cum/day 10,000
cum/day
Figure 5.3.2 Water Requirements and Exploitable Potential
-
Afghanistan Dehsabz South Groundwater Survey
JICA 5-19 DCDA
be as much as about 10,000 m3/day.
Figure 5.3.2 superimposes development potentials on the water
requirements, in which the potentials of 5,000 m3/day only from
Pol-e Charkhi, 8,000 m3/day from combined use of Pol-e Charkhi and
Tang Kalay, and 10,000 m3/day from the combined use of Pol-e
Charkhi and total potential of Tangi Kalay including the one owned
by the investor are assumed. From this figure, following are
indicated:
In case of only Pol-e Charkhi being developed, population of
approximately 200,000 could be served at the rate of 25
liters/day/capita, that of 100,000 at the rate of 50
liters/day/capita, and approximately 50,000 at 90
liters/day/capita.
In case of Pol-e Charkhi and Tang Kalay being developed
excluding the investor’s water use, population of approximately
300,000 could be served 25 liters/day/capita, that of 150,000 at
the rate of 50 liters/day/capita, that of approximately 75,000 at
the rate of 90 liters/day/capita, and about 50,000 at the rate of
150 liters/day/capita.
In case of Pol-e Charkhi and Tang Kalay being developed
including the investor’s water right, population of around 400,000
could be served with 25 liters/day/capita, that of 200,000 at the
rate of 50 liters/day/capita, that of approximately 110,000 at the
rate of 90 liters/day/capita, and about 70,000 with 150
liters/day/capita.
-
Dehsabz South Groundwater Survey Afghanistan
DCDA 5-20 JICA
5.4 Conceptual Development Designing
Based on the simple balance calculation by employing a concept
of perennial yield carried out in the aforementioned sub-chapter
5.1 and 5.2, it was found that only Pol-e Charkhi can be the
potential candidate site for the groundwater development amongst 4
sites. Though Tangi Kalay area has presented almost same potential
as that of Pol-e Charkhi, there should be prior negotiation with
the investor who owns large scale wells if DCDA wishes to exploit
the groundwater therein. If the negotiation is settled with a
success, it would be a better option to buy water from the existing
wells rather than establishing new wells. Therefore, conceptual
design is to be done for the Pol-e Charkhi area only.
5.4.1 Groundwater Development Potential and Production Wells
Groundwater development potential in the Pol-e Charkhi site was
estimated from around 4,800 to 5,900 m3/day as a gross development
potential, and around 230 m3/day5 shall be left from the
development for the existing water use including both irrigation
and domestic uses. Thus, a net groundwater development potential
comes to a level of about 5,000 m3/day. Then, based on the results
of pumping test in Pol-e Charkhi site, it was confirmed that the
aquifer in this site was excellent as indicating 3,400 m2/day of
Transmissivity (T), 0.0036 of Storativity (S) and 5.823 liter/sec/m
of specific yield.
The specific yield suggests that a proper designed production
well in this site can yield more than 29 liter/s inducing 5.0m of
drawdown, and this yield in terms of liter per second is equivalent
to 2,516 m3 per day. When considering the net groundwater
development potential, only two production wells have enough
capacity to exploit the potential as suggested by 2,516 m3/day x 2
wells = 5,031 m3/day, almost equal to the 5,000 m3/day of net
potential.
5.4.2 Drawdown by the Production Well
Accordance to Theis theory, when a well penetrating an extensive
confined aquifer is pumped at a constant rate, the influence of the
discharge extends outward with time. The rate of decline of head
times the storage coefficient summed over the area of influence
equals the discharge. Because the discharged water must come from a
reduction of storage within the aquifer, the head will continue to
decline as long as the aquifer is effectively infinite; this is
called as “Unsteady Radial Flow”. In a case of unsteady radial flow
in a confined aquifer, the drawdown is shown as a following
solution:
)(4
uWT
Qsπ
=
TtSru
4
2
=
where: s is drawdown (m), Q is discharge (pumping) rate (m3/day)
T is Transmissivity (m2/day) W(u) is Well function, u is an
indicator of W(u), r is distance from pumping well (m), S is
Storativity, and t is time of pumping (day)
5 In Pol-e Charkhi area, 90 m3/day for domestic water and also
138 m3/day for irrigation water are estimated now in use, totaling
228 m3/day. With this rough estimation, rounded amount of 230
m3/day is left for the domestic use and irrigation use for the
population.
……………………………………………………………(1)
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The equation was introduced for a confined aquifer but it can be
applied to an unconfined aquifer as well if the drawdown is not so
large as compared to the depth of aquifer, of course under the
assumption that the aquifer is completely homogeneous and extending
infinitely. As the equation indicates that the drawdown grows with
the pumping rate and diminishes with the increase of the distance
from the pumping well but it continues increasing steadily while
pumping is continued.
Table 5.4.1 shows a drawdown of sample calculation in case of a
production well in Pol-e Charkhi site under the conditions of 2,516
m3/day of pumping rate, 3,400 m2/day of Transmissivity, 0.0036 of
Storativity. As shown in the table, drawdown after 1 day pumping at
the point 30m far from the pumping well is only 46 cm, but it
increases up to 90 cm at 5 years later. Whereas after 5 years
continuous pumping, drawdown is 90 cm at the point 30 m apart from
the pumping well, it is still less than 36 cm at a far point 3 km
away from the well, if the actual aquifer condition is enough wide
and homogeneous.
Table 5.4.1 Calculation of Drawdown by Theis, Pol-e Charkhi
Site
5.4.3 Interference to the Existing Wells
Where a cone of depression between two nearby pumping wells
appears, as the case of Pol-e Charkhi, one well interferes with the
other because of its increased drawdown by pumping lift. For a
group of wells forming a well field, the drawdown can be determined
at any point if the well discharges are known, or vice versa. From
the principle of superposition, the drawdown at any point in the
area of influence caused by the discharge of several wells is equal
to the sum of the values of draw-down caused by individual wells.
Thus,
sT = sa + sb + sc + ・・・+ sn…………………………………………………………(2)
where T is the total drawdown at a given point and sa, sb, sc,
・・・ sn are the values of draw-down at the point caused by the
discharge of wells a, b, c, ・・・, n, respectively. The situation is
shown in
Time 4Tt S/4Tt u=r2S/4Tt r=30m r=100m r=200m r=300m r=400m
r=500m r=1000m r=2000m r=3000m
1day 13600 2.64706E-07 u= 0.000238235 0.002647059 0.010588235
0.023823529 0.042352941 0.066176471 0.264705882 1.058823529
2.382352941W(u)= 7.758 5.3776 3.9463 3.176 2.634 2.206 1.014 0.186
0.028s= 0.457 0.317 0.232 0.187 0.155 0.130 0.060 0.011 0.002
10day 136000 2.64706E-08 u= 2.38235E-05 0.000264706 0.001058824
0.002382353 0.004235294 0.006617647 0.026470588 0.105882353
0.238235294W(u)= 10.06 7.678 6.236 5.458 4.9 4.45 3.098 1.737
1.076s= 0.592 0.452 0.367 0.321 0.289 0.262 0.182 0.102 0.063
1mon 408000 8.82353E-09 u= 7.94118E-06 8.82353E-05 0.000352941
0.000794118 0.001411765 0.002205882 0.008823529 0.035294118
0.079411765W(u)= 11.171 8.761 7.381 6.567 5.996 5.544 4.165 2.81
2.039s= 0.658 0.516 0.435 0.387 0.353 0.326 0.245 0.165 0.120
3mon 1224000 2.94118E-09 u= 2.64706E-06 2.94118E-05 0.000117647
0.000264706 0.000470588 0.000735294 0.002941176 0.011764706
0.026470588W(u)= 12.283 8.695 8.538 7.64 7.086 6.632 5.269 3.858
3.098s= 0.723 0.512 0.503 0.450 0.417 0.391 0.310 0.227 0.182
1year 4964000 7.25222E-10 u= 6.52699E-07 7.25222E-06 2.90089E-05
6.52699E-05 0.000116035 0.000181305 0.000725222 0.002900886
0.006526994W(u)= 13.669 11.25 9.871 9.064 8.451 8.046 6.646 5.269
4.465s= 0.805 0.662 0.581 0.534 0.498 0.474 0.391 0.310 0.263
2y 9928000 3.62611E-10 u= 3.2635E-07 3.62611E-06 1.45044E-05
3.2635E-05 5.80177E-05 9.06527E-05 0.000362611 0.001450443
0.003263497W(u)= 14.347 11.957 10.53 9.742 9.178 8.728 7.353 5.927
5.14s= 0.845 0.704 0.620 0.574 0.540 0.514 0.433 0.349 0.303
3y 14892000 2.41741E-10 u= 2.17566E-07 2.41741E-06 9.66962E-06
2.17566E-05 3.86785E-05 6.04351E-05 0.000241741 0.000966962
0.002175665W(u)= 14.752 12.363 10.966 10.147 9.575 9.144 7.758
6.362 5.544s= 0.869 0.728 0.646 0.598 0.564 0.538 0.457 0.375
0.326
4y 19856000 1.81305E-10 u= 1.63175E-07 1.81305E-06 7.25222E-06
1.63175E-05 2.90089E-05 4.53263E-05 0.000181305 0.000725222
0.001631749W(u)= 15.071 12.651 11.35 10.466 9.871 9.432 8.046 6.646
5.862s= 0.887 0.745 0.668 0.616 0.581 0.555 0.474 0.391 0.345
5y 24820000 1.45044E-10 u= 1.3054E-07 1.45044E-06 5.80177E-06
1.3054E-05 2.32071E-05 3.62611E-05 0.000145044 0.000580177
0.001305399W(u)= 15.289 12.833 11.48 10.673 10.103 9.655 8.228
6.876 6.07s= 0.900 0.756 0.676 0.629 0.595 0.569 0.485 0.405
0.357
Source: JICA Sub-project team
Figure 5.4.1 Interferences of Drawdown
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Figure 5.4.1.
Where a well is pumped near an aquifer boundary, the assumption
that the aquifer infinitely extends is no longer valid. An example
seen in the site is the situation of a well near a perennial
stream. Because of the continuous recharging from a perennial flow,
pumping water level (cone of depression) is modified as if there is
an imaginary well system at the opposite side of the flow.
Sectional view is exampled in Figure 5.4.2.
Taking these conditions; interference of production wells and
recharging from perennial flow, into consideration, drawdown of
groundwater taking place around the production wells was estimated
through MODFLOW model simulation. Figure 5.4.3 shows a sample of
drawdown contour map 5 years after two of the wells started
pumping, shown in meter. In this simulation, the production wells
have been operated at the rate of 2,500 m3/day each. In the figure,
the contour lines are 0.1m interval, and water level of the Kabul
River is GL. -14.0m.
5.4.4 Design of New Production Wells
As explained above, two newly drilled production wells are
required, which must yield more than 2,500 m3/day under at least
30m of water-head ((S.W.L 14m + D.D 5m) x 1.5). However, one new
large scale Test Well which can be converted to a production well
later shall be drilled at first in order to confirm the well yield
more precisely. Pumping rate of more than
Figure 5.4.2 Sectional View of Discharging Well near a Perennial
Flow
5 Years After
0 2000 4000 6000 8000 100000
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000Kabul River : GL.-14m
Well Point : No.1
Well Point : No.2
Pol-e Charkhi Case.6 : Q=5,000m3/s (No.1+No.2)
Figure 5.4.3 Groundwater Contour under pumping
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2,500 m3/day means nearly 30 liter/sec, rather large amount of
yielding, and to pump up such large amount of groundwater at least
φ10” well must be required. To make up 10” well, drilling by
18-1/2” bit is needed. Thus, the structure of the production well
shown in Figure 5.4.4 is recommended.
As shown in the figure, drilling diameter shall be 18-1/2”
throughout the drilling, excepting an uppermost span of conductor
pipe (6.0m), and the well depth shall be at least 40 m considering
the geological condition of the site. Screen must be a wired type,
so called “Johnson’s Screen” to obtain enough open ratio of more
than 25%. Since the screen is set from the depth of 25m to 35m, the
submersible motor pump shall be set at around 25m, just upper point
from the screen pipes.
Two production wells will be drilled in the premises of Pol-e
Charkhi Radio Station to avoid any land ownership conflict with the
villagers, and shall be 1.0 km apart each other so as not to make a
heavy interference. One of the two wells shall also work as a new
test well, location of which can be at 531.500 / 3821.700 in UTM
(1K unit) as recommended in Figure 5.4.5.
Compensation for the villagers may have to be considered. To
identify such influence by the pumping at an earliest date, a
monitoring system on groundwater level must be established before a
full scale development is to commence. A monitoring system is
therefore to be discussed in latter sub-chapter (Sub chapter
5.5).
5.4.5 Conceptual Design of Pipeline
If the proposed water resources site were selected in the
Dehsabz sub-basin, it might have been much
Figure 5.4.5 Location of New Test Well
●Production well No.2 (New Test Well)
●Production well No.1
Figure 5.4.4 Structure of New Test Well
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DCDA 5-24 JICA
easy to transport the water to the new city. However, possible
groundwater resources development site is only Pol-e Charkhi site
within the Kabul Basin. On top of this, the recommended production
wells are to be installed inside of the Radio Station located at
southern bank of the Kabul River. It means that the pipeline to
carry the water shall pass across the river along with the newly
constructed road and bridge joining the Jalalabad road.
Pipeline will pass across the road after crossing the bridge,
then go west along with the northern side of the road. At a
location around 3 km west from the joint with the road, the
pipeline will turn to north along with the by-pass road to the
Bagrum Road, just along with the district boundary between District
9 and District 19. After joining the Bagrum Road, the pipeline
shall go further north along with the Bagrum Road approaching the
new city. Total pipeline length is to be around 17 km. The rough
route map of the pipeline is shown in Figure 5.4.6. As shown in the
figure, the pipeline starts at the two production wells to be
established in the Radio Station and the ends at a reservoir near
the new city just beside the road.
5.5 Monitoring System for Groundwater Table
There are two categories of monitoring systems in this project;
one is to monitor the natural ground water level of the three
target sites for a basic hydrogeological data in Dehsabz Basin and
another is to observe groundwater drawdown to be caused by the
pumping inside the Radio Station influencing the outside.
5.5.1 Monitoring of Natural Groundwater Table
For the drilled three (3) wells under this Sub-project, after
having placed concrete made basement (see photo as an example),
they are to be so arranged that regular measurement of the
groundwater level can be done. The frequency of groundwater level
measurement can be as a rule once a month. This measurement may be
carried out by DCDA supported by the Project on the Promotion of
Kabul Metropolitan Area Development.
Figure 5.4.6 Outline of the Pipeline
Concrete made basement placed at the well for Bakhtyaran
site
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JICA 5-25 DCDA
This Sub-project is therefore to provide them with a manual
showing procedures of the measurement and items to be taken. If the
measurement is to be entrusted to a third party, the Sub-project
Team is to prepare a standard contract form and the TOR.
5.5.2 Monitoring the Interference to be caused by Production
Wells
In the previous section, draw-down to be caused by pumping at
the production wells was explained. As shown in Figure 5.5.1, large
parts of Pol-e Charkhi village will be affected by the pumping from
the production wells but the influence is not anticipated serious
judging from the result of the MODFLOW simulation. However, natural
hydrological condition is not homogeneous, not infinitely equal.
Therefore, it is quite important to monitor the values of actual
groundwater draw-down in and around the production wells.
Major purpose of the monitoring is to evaluate an influence of
the groundwater drawdown to be caused by operations of the
production wells, so that the monitoring must be done to the
directions most affective and must be commenced before the
production wells start pumping. The proposed locations of the
monitoring wells are shown in Figure 5.5.1. (Drawdown contours
shown in the figure are only a reference). As shown in the figure,
total three monitoring wells are required to observe the state of
draw-down at the north, east, and south directions. The proposed
locations are:
M1: 532000 E/ 3822200 N M2: 532850 E/ 3821800 N M3: 532000 E/
3821500 N
Depths of the monitoring wells are to be the same as that of the
production wells, 50m, but drilling diameter is to be 7” to 8” and
completed by 4” screen and casing. Rough design of the monitoring
well is shown in Figure 5.5.2. In case of observation wells, PVC
casing and slotted screen can be applied. Screen depth shall be
fixed from 25 to 35m in depth, the same as that of the new test
well.
Figure 5.5.1 Location Map of Monitoring Wells
Figure 5.5.2 Structure of Monitoring Well
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5.6 Way-forward to the Population’s Consent for Groundwater
Exploitation
The prime target is Pol-e Charkhi area for the groundwater
development of the Dehsabz new city. Secondary target may be Tang
Kalay area, however in this area there are already 3 large wells
owned by an investor. Therefore, the development in this Tangi
Kalay area will firstly depend on the result of the negotiation
with the owner since there is no more potential to further exploit
the groundwater other than those large wells. To this end, the
way-forward to develop the groundwater including EIA clearance and
the population’s consent should center on the Pol-e Charkhi
area.
5.6.1 Groundwater Development in line with Legal Aspects
There is a law stipulating water related issues in Afghanistan,
called Water Law6 issued at a Gazette No. 974 – 28, February 2009.
In addition, there is environmental related law called
Environmental Law, official Gazette No.912 dated 25 January 2007,
and its relevant Environmental Impact Assessment Regulations
(Gazette No.939, 10 March 2008). This session refers to these 2
laws to know the legal aspects to be required for the groundwater
development:
1) Water Law
The Water Law has total 40 articles and governs not only surface
water development but also groundwater development. The project for
the groundwater development shall refer to the law especially for
securing water right to develop and utilize the groundwater.
Relevant articles in the law are cited and presented as below:
The water is defined as a public property and the government is
responsible for its protection and management by Article 2 -
Ownership and Management of Water. The Article 3 defines the
definitions and terminologies used in the Law wherein groundwater
is governed under this Law defining that groundwater is all waters
beneath the ground surface at different depths (aquifer) including
springs, Karezes, deep and ordinary wells.
Article 8 - Responsibilities of Governmental Institutions
stipulates that the ownership of all waters in the country belongs
to the people of Afghanistan and the government is responsible for
their protection, control, management and effective use in
accordance with the law. With this article, practical enforcement
is stated as that MEW is responsible for planning, management and
development of water resources in collaboration with concerned
ministries and agencies, and for the groundwater the MoM shall be
responsible in close collaboration with MoPH7 and also NEPA.
Aside from the line ministries, the Law stipulates under Article
13 ‘River Basin Council (RBC)’ that the MEW shall establish a River
Basin Committee composed of members representing water users,
relevant national and local agencies and other stakeholders in the
river basin (as at July 2011, no RBC has been established, though).
The article further says that the MEW may delegate, when
appropriate, some of its powers to the RBC in accordance with the
law, after improving the required working capacity and capability
through technical trainings. To this end, the one who shall issue
water permit is the RBC, if already established, as stipulated
under No.5 provision of Article 14 – Functions of the RBC, i.e.;
‘Issue, register, change or cancel permits and maintain relevant
documents’.
6 Referred to in an Unofficial English Translation by EIRP
(Emergency Irrigation Rehabilitation Project) /FAO, Edited by UNEP
and KRBP (Kunduz River Basin Programme) - July 6, 2009 7 Though the
provision of Article 8 does not specify how to collaborate with MPH
and NEPA, there is an understanding that the MPH should provide
recommendations for the safe water quality in terms of chemical and
bacteriological compositions. NEPA is the responsible agency for
EIA clearance where required. In addition, NEPA is relevant with
the protection of any water sources to be developed in
Afghanistan.
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The Law states necessity of carrying out an environmental impact
assessment in the Article No. 32 - Adverse Effects on the
Environment. The article stipulates that the owners/proponents of
any substantial water resources development projects shall be
responsible for conducting Environmental Impact Assessment (EIA) at
their own cost in accordance with Environmental Law and policy.
Though the level of ‘substantial’ is not stated in the Law, the
envisaged groundwater development for the new Dehsabz city will be
categorized under this ‘substantial water resources development
projects’ since the scale of the development goes beyond what the
ordinary individual households require for their domestic
purpose.
There is an article stipulating deep well drilling, namely,
Article 38 - Deep Wells Drilling. This article states that the deep
wells may be drilled only after obtaining an authorization from MoM
for agriculture, commercial, industry and urban water supply
purposes. Digging ordinary wells to meet the need for drinking
water and livelihood purposes is exempted from this provision.
2) Environmental Law and its Regulations
The Environmental Law was enacted on January 25, 2008 by the
National Assembly, and has total 78 provisions, following which
Environmental Impact Assessment Regulations was gazetted on March
10, 2008. Relevant articles that shall refer to in developing
groundwater are:
National Environmental Protection Agency (NEPA) is designated as
an independent institutional entity responsible for coordinating
and monitoring conservation and rehabilitation of the environment,
and for implementation of the Environmental Law under Article 3.
This NEPA is therefore the sole agency to authorize on the advice
of the EIA Board of Experts the project submitted by a proponent,
provided that any significant adverse impact on the environment
takes place.
There is an article under the Law specifying public
participation – Article 19 – Public Participation. The article
states that the NEPA shall not reach a decision on any application
for the permit until such time that the proponent has demonstrated
to the satisfaction of the NEPA that the proponent has distributed
copies of the document to affected persons, informed the public
that the document is being made available for public review by
advertising the document and display a copy of it for inspection,
and convened and recorded the proceedings of a public hearing.
The Article 19 under the Law further says that after the NEPA
has reviewed the conditions set in the aforementioned statement,
the NEPA shall reach a decision and inform the pubic of that
decision and make available any relevant documentation or
information for public review.
In line with the Law excerpted above, the Regulations elaborates
procedure of application in order to acquire permission for a
project which may affect environment and its screening. Regulation
4 – Applications states that an applicant shall submit to the NEPA
an application form in accordance with schedule specified in the
Regulations. Regulation 5 – Screening8 points out that the
proponent shall conduct a screening process and complete a
screening report consistent with international best practice, which
is to be submitted to NEPA for its decision for the permission.
Then, the NEPA may require the applicant to carry out
environmental impact assessment process. If the applicant is
instructed to do so by the NEPA, the applicant shall prepare
environmental impact statement, which statement shall contain all
the information required for the NEPA to
8 In relation to this, activities are categorized in 2; Category
1 and Category 2. No groundwater related activities are listed in
the categories, however there is an activity of ‘water supply and
treatment’. With reference to this category, a water supply scheme
with a total cost of US$ 400,000 or more is categorized under
Category 1 Activities while less than that water supply projects
under Category 2 Activities.
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DCDA 5-28 JICA
make a decision if it is permitted or not.
2) Procedure to EIA Clearance and Water Right to Secure
Taking account of above cited provisions of the Laws and
Regulations relating to this groundwater development, DCDA is
required to take following actions:
1) The production wells are to be constructed in the premises of
Pol-e Charkhi Radio Station which is placed under the supervising
authority of the National Radio and Television of Afghanistan
(NRTA) of the Ministry of Communication and Culture. To construct
the production wells within the premises, DCDA should start
discussing with the Ministry of Communication and Culture for the
permission of constructing the well(s), though this is not directly
related to the requirement of the environmental law.
2) At the same time, DCDA to hold a public hearing meeting(s)
inviting the population of the Pol-e Charkhi village (refer to
Box). The size and contents of the development including the volume
of the groundwater exploitation will be explained to the villagers.
Expected drawdown of the groundwater table shall also be thoroughly
explained with its monitoring system (For the procedure and the
contents of the meeting are discussed in the following
section).
3) In line with above 1) and 2) processes, DCDA to prepare for
Screening of the groundwater development project required under the
Environmental Law which is also a part of EIA. The contents of this
Sub-project shall fully be utilized especially for the design of
the works, scale of the groundwater development, level of expected
negative impacts represented by drawdown of the groundwater table
and mitigation measures including monitoring system. The EIA should
incorporate the discussion results with and the consent from the
villagers of the Pol-e Charkhi for the development of the
groundwater.
4) Upon the consensus by the Pol-e Charkhi population and
permission for the construction of the wells within the premises by
the Ministry of Communication and Culture, DCDA will complete the
EIA statement and submit to the concerned authority, NEPA, for
authorization of the project. Upon approval, DCDA to prepare for
and submit an application form of the water work, which here means
the groundwater development works composed mainly of 2 deep wells
construction, to the MEW. In fact, though the application is
supposed to go to the River Basin Committee, the committee has yet
to be established whereby to the supervising authority, namely, to
the MEW. In addition, DCDA has to submit the plan/design for the
deep well(s) to MoM for the authorization of the work.
5) Upon the granting of the permission, the DCDA may proceed
with the construction of the deep well(s) in the premises of the
radio station. The premises is a government property, and therefore
no financial compensation for occupying a land, approximately 5m
square each per well, for the construction of deep well(s) may be
required on condition that the DCDA and the Ministry of
Communication and Culture are in agreement.
People’s involvement/participation in EIA: In line with EIA
procedure, the people who may be affected by the project should at
least be given all the relevant project information (level-1),
which is usually called ‘involvement of the population’. This also
requires the implementing agency to discharge the responsibility of
accountability to the people. On top of the involvement, there may
be 2 levels in which the people participate. One is the
participation to decide which alternative plans to be provided by
the implementing agency shall be the best (level-2), and the other
is that the people themselves participate in the design of the
alternative plans and decide on them by themselves (level-3).
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5.6.2 Consensus on Groundwater Development from the Pol-e
Charkhi Population
From the viewpoint of accepted customs and traditions, there are
some statements given by some of the Shura members during the
explanatory meetings arranged for the purpose of arriving at
consensus on the conduct of the surveys under this Sub-project. The
custom and tradition may suggest that the property right of the
landowner does not govern that of the groundwater beneath his/her
land.
It means that as far as the new development does not negatively
affect the present use of groundwater, the villagers shall not
claim any compensation for the groundwater exploitation according
to costmary practices. This custom is also in accordance with the
Water Law wherein water is specified as public property under
Article 2 - Ownership and Management of Water.
According to the Water Law, DCDA is required to conduct EIA for
this groundwater development project. The EIA procedure, according
to the Environmental Law, requires DCDA to conduct public hearings
from the Pol-e Charkhi population who may be affected by the
project. Though the well(s) are to be constructed within the
government premises, it is still necessary to hold the public
hearing meetings with the Pol-e Charkhi villagers for the
groundwater development as far as there is a possibility that they
may be affected, otherwise the EIA procedure can not be
completed.
Taking above conditions into consideration, following procedures
are recommended to arrive at the consensus with the Pol-e Charkhi
villagers for the development of the groundwater:
1) DCDA to invite village representatives such as CDC members
and Shura members through Malik for the public hearing meeting(s).
The meeting should also invite some villagers concerned who are
heavily dependent on the groundwater, e.g. farmers with irrigation
wells and nearby households who are dependent on the groundwater
for their domestic uses. Villagers who reside outside the radius of
2 km may not be requested to attend the meeting since the impact
will be negligible.
2) During the meeting, the DCDA will explain the plan/design of
the groundwater development and also its relevant impact. DCDA will
also request the village representatives who attended the meeting
to hold small meetings in their areas to further discuss and
explain the information provided by the DCDA. DCDA will inform the
participants in the meeting of the following, and at the same time
shall make all the relevant documents and information public/
available:
Rationale and the purpose of the groundwater development in the
Pol-e Charkhi area,
Timeframe of the groundwater exploitation, which refers to the
time when the water resources at the Panjishir fan is to be
developed,
Development plan/design and the volume of the groundwater to be
exploited by development stage (by year) in correspondence with the
exploitable potential which exists in the Pol-e Charkhi area,
Expected impact especially in the form of drawdown of the
groundwater table,
Monitoring system, and
Measures to cope with negative impact such as drawdown of the
groundwater table which goes beyond allowable level.
3) DCDA and the village representatives will prepare record of
discussions including issues and agreements made. The document
should clarify the consensus with the villagers on the groundwater
exploitation and also the measures to be taken in case that
unallowable negative impact happens.
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DCDA should have in mind that as regards drawdown by more than
50cm from the present groundwater level it should notify the water
users of what is happening on their groundwater through general
communication practices. In case that groundwater level goes down
by more than 50 cm from the original level, the users can feel that
the pumping gets harder bit by bit due to the increased load and
also the escalated time lag between starting the pumping and the
moment the water starts pouring out. However, this situation does
not instantly require the users to seek compensation since users
still can avail of groundwater.
According to the well structure in the Pol-e Charkhi area, the
level of drawdown which makes existing wells very hard to pump up
groundwater would be from 2-3 meters or more. In fact, if the
drawdown reaches as much as 5m, there will be many wells that will
dry up. However this situation would hardly take place according to
the simulation results by MODFLOW.
MODFLOW analysis has identified the drawdown of the groundwater
under different pumping ratios of groundwater exploitation. Table
5.6.1 summarizes the drawdown of the groundwater table in case of
total 5,000 m3/day pumping (2,500 m3/well x 2 wells) with time of
lapse and by distance from the wells. From the table, it can be
said that the present users would hardly be affected to a level at
which they would have great difficulty of pumping up groundwater
whereby needing compensation:
In detail, after a year since the pumping started, the
groundwater drawdown will be only 66 cm even at a distance of 30m
from the pumping well and only 27 cm at a place 1 km away from it.
Likewise, 5 years later since the pumping started, the drawdown
will be 74 cm and 42 cm at the place of 30 m away and at the place
of 1 km away, respectively. From these results, though user
villagers
would notify the drawdown of the groundwater to at least some
extent, they would have very little difficulty in pumping up the
water.
For the compensation should the case take place, the best way
may be to install public taps sourced from the production well(s).
The public taps, if needed, should be installed along existing
village roads. Of course, the positioning of the taps should fully
incorporate the users’ views. To provide the compensation water to
about 50% of all the Pol-e Charkhi population as an example, there
would be about 90 m3/day of domestic water based on a per-capita
water requirement of 50 liter per day. Aside from this domestic
use, there are 14 irrigation wells in Pol-e Charkhi area. One well
usually provides about 40 m3/day during the irrigation period of 3
months. Though it is not likely for all the wells to be affected,
the maximum compensation, if needed, would reach 560 m3/day for the
3 months from May to July.
Table 5.6.1 Drawdown of the Groundwater, 2,500m3/day x 2
WellsDistance from the Well
Day/Year 30 m 100 m 1.0 km
Day 1 -0.208 -0.073 0.000 Day 10 -0.351 -0.205 -0.003
Day 100 -0.552 -0.406 -0.117 Year 1 -0.658 -0.516 -0.268 Year 2
-0.699 -0.560 -0.341 Year 3 -0.718 -0.580 -0.377 Year 4 -0.730
-0.593 -0.401 Year 5 -0.739 -0.603 -0.419 Year 5 -0.739 -0.603
-0.419
-
Afghanistan Dehsabz South Groundwater Survey
JICA 6-1 DCDA
CHAPTER 6 GROUNDWATER DEVELOPMENT -2 (ADDITIONAL TEST WELL) 6.1
General
As explained in Chapter 4 and Chapter 5, the target site No.2,
Pol-e-Charkhi area is the only site which has substantial
groundwater development potential, on which present level of
groundwater use is estimated below the annual rechargeable amount
among total four candidate sites in this Sub-project. However, as
described in Section 4.2.1 “Test Well Drilling General”, the test
wells drilled in the study were finalized by 6” casing and screen,
and also as shown in Section 4.2,3 “Pumping Test Results”, the size
of test well drilled in Pol-e-Charkhi site was not enough to set a
submersible pump with large discharge amount. On the other hand,
total groundwater development potential in Pol-e-Charkhi site was
estimated as 5,960 m3/day (Section 5.1.2), and exploitable
groundwater potential was evaluated as around 5,000 m3/day (Section
5.3.2). The volume can be exploitable by only two production wells
(2,500 m3/day/well, nearly 28.9 lit/sec/well) because of very
excellent hydrogeological condition of the site.
However, actual pumping rate in the Constant Discharge Test in
TW-Pol was only 3 lit/sec, and alternative pumping well (existing
well in RTA compound) had rather enough discharge rate at around 24
lit/sec though no well design nor aquifer information were
available. Thus, an additional test well was required to be drilled
which had enough large casing diameter for setting submersible pump
yielding around 30 lit/sec, and can be diverted to a Production
Well after completing series of tests as a test well.
Based on such requirement, an additional test well with 10
inches casings and screens which were enough to yield around 30
lit/sec of groundwater was planned out, and implemented. The new
test well (hereinafter called as TW-N) was sited by field
reconnaissance around RTA compound (Radio S