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

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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

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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

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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