Bangladesh Flood Risk Update Flood Risk Rising World Food Programme (WFP) Disaster Risk Reduction (DRR) 29 th August 2008
Jan 03, 2016
Bangladesh Flood Risk Update
Flood Risk Rising
World Food Programme (WFP)Disaster Risk Reduction (DRR)
29th August 2008
Overview Factors contributing to higher risk Regional Geography; Up-Stream
Perspective Situation in Bangladesh Situation Upstream Risk of significant flooding is now higher;
situation has changed Higher risk areas in Bangladesh Preparedness Actions Needed
Regional/Upstream Perspective Critical
In an average year, during May-October, about 1 trillion cubic meters of water flows through Bangladesh
17% of that water comes from rainfall inside Bangladesh
83% is “In-flow”; from rain and rivers outside the country
78% of the in-flow comes via the three main rivers; Bhramaputra-Jamuna, Ganges/Padma, and the Meghna
Regional perspective (i.e. Upstream monitoring…) matters; - - A lot !!
Source: Banglapedia
M e
g h
n a
Up-Stream Drainage BasinsUp-Stream Drainage Basins
Brahmaputra
Brahmaputra
Meghna
Ganges-Padma
Tista
11
22
33
Assam
Bihar
Assam
Sikkim
NepalNepal
Assam
Meghalaya
BhutanBhutan
Up-Stream Basins and Rivers1. Bihar/W. Bengal: Ganges-Padma
2. Assam: Brahmaputra-Jamuna + Sikkim: Tista
3. Meghalaya/Assam: Meghna
Approach/Methodology
For Each Basin (Map-Zone) we look at Known/Confirmed Flooding Events (if any)
Causes; Updates River Levels: current River Level: forecasts and trends Rainfall: forecasts and trends Flood Risk: near term (approx.
next 3-5 days)
M e
g h
n a
Ganges-Padma
11Assam
Bihar
AssamNepalNepal
Assam
Meghalaya
BhutanBhutan
Up-Stream Basins and Rivers1. Bihar/W. Bengal: Ganges-Padma
Sikkim
Major Floods in Bihar IndiaWhat Happened?
Nepal’s Kosi River Dam breaks; 18th August; embankments downstream breached
Major flooding occurs in Nepal, and downstream in Bihar Bihar: 2-3 Million people affected, Nepal: more than 100,000 displaced
Where in Nepal and India?Proximity to Bangladesh?
Origin of Kosi Flood
W. Bengal
Kathmandu
Nepal
Causes of Kosi Flood?
Heavy Rainfall?
Rainfall: 11th-20 August2008 Percent of Normal
2008 vs. Avg.( % Change )
400%
200%
125%
110%
90%
75%
50%
25%
10%
Notes:
1. Kosi Dam breaks 18th August
2. Rainfall was 2 to 4 times (200-400%)higher than Normalfor period 11th-20th August.
3. Heavy Rains not wide-spread; but location specific at Nepal-India Kosi area border.
4. Not entirely clear whether rain highlighted in map played a “causal” role.
5. Rainfall Source: USAID FEWSNET
RFE-2
6. “Normal” based on a 7 yr. Average.
Nepal
India
Bangladesh
Bhutan
Bihar WestBengal
WestBengal
Proximity to Bangladesh? Zoomed View
Nepal Nepal
Bihar
Bihar
Bangladesh
Rajshahi
Nawabganj
Rangpur
Bihar
W. BengalW
. Ben
gal
W. B
engal
FFWC Padma Stations relatively close to W.Bengal/Bihar
What is happening w/ river levels in these areas?
Source: FFWC29 Aug. 2008
Source: Google Maps, Maplandia
Graphs of Water Levels (Hydrographs) 2 FFWC Stations;
Padma River Nawabaganj DistrictTrends; Flat/Steady
Trends at 3 Normal (Green)
Stations also flat/steady
What is happening w/ river levels Up-
Stream:Bihar and
Surroundings ? 21 Stations at
or above Warning Level.
13 of 21 at Danger Level or Higher
8 of 21 at Warning Level or Higher and below Danger Level
Source: India Central Water Commission
River level measurements taken morning of 29th August
Information above pertains to Bihar, W. Bengal, Jharkhand
Data changes Frequently; latest Updates available at :
http://www.india-water.com/ffs/index.htm
Up-Stream River Level TrendsBihar and Surroundings
Number of Stations
26 Aug 27 Aug 28 Aug 29 Aug
Warning Level (or Higher)
Danger Level (or Higher)
Rainfall Forecast: Bihar and SurroundingsTotal Rain: Morning of 29th Aug. thru Morning of 1st
Sept.
Bihar and Surroundings
mms.
Rain Forecast:Very Light to Light
What is happening w/ river levels Up-Stream:
Assam and Surroundings ?
8 Stations at or above Warning Level.
3 of 8 at Danger Level or Higher
5 of 8 at Warning Level or Higher and below Danger Level
Source: India Central Water Commission
River level measurements taken morning of 29th August
Information above pertains to Bihar, W. Bengal, Jharkhand
Data changes Frequently; latest Updates available at :
http://www.india-water.com/ffs/index.htm
M e
g h
n a
Up-Stream Drainage BasinsUp-Stream Drainage Basins
Brahmaputra
Brahmaputra
Meghna
Ganges-Padma
Tista 22 Assam
Assam
Sikkim
NepalNepal
Assam
Meghalaya
BhutanBhutan
Up-Stream Basins and Rivers
2. Assam: Brahmaputra-Jamuna + Sikkim: Tista
Up-Stream River Level TrendsAssam and Surroundings
Number of Stations
26 Aug 27 Aug 28 Aug 29 Aug
Warning Level (or Higher)
Danger Level (or Higher)
Rainfall Forecast: Assam and SurroundingsTotal Rain: Morning of 29th Aug. thru Morning of 1st
Sept.
mms.
Rain Forecast:Light to Moderate Assam and
Surroundings
What is happening w/ river levels Up-Stream:Meghalaya-Assam and
Surroundings ?
8 Stations at or above Warning Level.
None at Danger Level or Higher
One at Warning Level or Higher and below Danger Level
Source: India Central Water Commission
River level measurements taken morning of 29th August
Information above pertains to Bihar, W. Bengal, Jharkhand
Data changes Frequently; latest Updates available at :
http://www.india-water.com/ffs/index.htm
M e
g h
n a
Up-Stream Drainage BasinsUp-Stream Drainage Basins
Brahmaputra
Brahmaputra
Meghna
Ganges-Padma
Tista
NepalNepalBhutanBhutan
Up-Stream Basins and Rivers
3. Meghalaya/Assam: Meghna
Meghalaya 33
Up-Stream River Level TrendsMeghalaya-Assam and Surroundings
Number of Stations
26 Aug 27 Aug 28 Aug 29 Aug
Warning Level (or Higher)
Danger Level (or Higher)
Rainfall Forecast: Meghalaya-Assam and Surroundings
Total Rain: Morning of 29th Aug. thru Morning of 1st Sept.
mms.
Rain Forecast:Light to ModerateA
ssam
Meghalya
Bangladesh South-East Chittagong, Cox’s Bazar and
Surroundings
In addition to the analysis presented in previous slides Very Heavy Rain has fallen in SE Bangladesh; and Flash Flooding has occurred
Some assistance has been provided; GoB and UNICEF
Conclusions/Recommendations
Flood Risk in Bangladesh has become higher in recent days; mostly because of heavy rain and high river levels Up-Stream; and also because of heavy rain in some areas of Bangladesh
Situation has deteriorated and may continue to deteriorate in coming days
Close Monitoring needed Stepping up preparedness for potential
rapid response warranted