Water Club 18th March, 2010, IWM, Dhaka

Performance of Flood Control Performance of Flood Control Works around Dhaka City during Works around Dhaka City during

Major Floods in BangladeshMajor Floods in Bangladesh(Part(Part--2)2)

Sujit Kumar Bala

Institute of Water and Flood Management (IWFM)Bangladesh University of Engineer and Technology (BUET)

Outline

• Flood Control works of the city

• Performance during major floods

• Field investigations during major floods

Flood Control Works of Dhaka City

Drainage System of Dhaka City

Natural drainage system: 40 Khals(canals), lakes and lowlands (provide detention storage)

Storm sewer system: 225 km underground pipe, 8 km box culvert12 Drainage zones (JICA, 1987)6 Drainage compartments and sub-compartments (JICA, 1991 and 1992)

3 permanent pump stations in the western part (54 m3/sec total pumping capacity)

Dhaka West

Dhaka East

Source: Khan et al., 2010 IWFM, BUET

Flood Control works of Dhaka City

The The Greater Dhaka city is Greater Dhaka city is divided into Dhaka West and divided into Dhaka West and Dhaka EastDhaka East, which is our study , which is our study areaarea

The city is surrounded by The city is surrounded by thetheBuriganga at the south, Buriganga at the south, the the Turag at the west, Tongi Khal at Turag at the west, Tongi Khal at the north and the north and the the Balu at the Balu at the east.east.

Locations of pumped drainage in Dhaka West during 1998 flood

Locations of pumped drainage in Dhaka West during 2004 flood

Flood control works in Dhaka City

About 30 km of earthen embankment.About 37 km of raised road and floodwalls. A total of 11 regulators at the outfall of Khals. 1 regulator and 12 sluice gates on the Khals. Three pump stations namely Kallyanpur, Goranchat Bari and Dholai Khal pump stations.

Performance of Flood Control Works

Areas flooded by river water and floodwater intrusion points during 1998 flood

Areas flooded by river water and flood water intrusion points in 2004 flood

Performance of Flood control works around Dhaka city during 2007

-0.5

0

0.5

1

1.5

2

2.5

3

3.5Ju

l-22

Jul-2

7

Aug-

01

Aug-

06

Aug-

11

Aug-

16

Aug-

21

Wat

er L

evel

diff

eren

ce in

m,P

WD

Goran chatbariKallayanpurDholai KhalSegun bagichaRampura

ConclusionsFlood protective embankment worked very well.

Internal flooding was observed surfacing out as one of the disasters for protected Dhaka West.

Breaks out of diarrhoeal diseases during 2007 flood.

Urban encroachments have increased and reduced retention pond area of the Kallaynpur and Goranchat Bari pump stations.

Field investigations during major floods

Flood 1998

Boat transport in the roads of Dhaka East for more than one month during 1998 Flood

A 2.2 km incomplete embankment at Kellarmukh, which was exposed to Buriganga River flooding

during 1998 flood

Slum and deterioration of embankment near Rayer Bazar during 1998 flood

Garbage dumping along the flood protective embankment near Kallaynpur Pump Station

during 2004 Flood

Flood 2004

People were using boats as transport in Golapbag during 2004 Flood

Social Conflicts around Regulator (FS13) during Flood 2004

Residential buildings around Gulshan lake during internal flooding of 2004 Flood

Water quality of extreme bad type near Golapbag during 2004 Flood

Flood 2007

Rampura temporary pump station shows negligible impact on drainage congestion

Temporary pumps near Hazaribag discharge untreated waste water which cause serious pollution

of Buriganga river

Retention ponds of Kallayanpur pump station Encroachments gradually increases and

reduces retention pond area.

Dredging in Turag river filsl wetlands of Dhaka west. Serious thread to retention ponds of

Goran chatbari pumping stations.

Floating mat of waste on Dholai khal indicates poor solid waste management of the Dhaka city

References

Chowdhury et al. (1998) of IWFM have studied the impact of 1998 flood on Dhaka city and performance of flood control works.

Rahman et al. (2005) of IWFM have investigated the hydrologic aspects of Flood 2004 in major rivers of Bangladesh and special emphasis has given on the floods of Dhaka city.

Islam et al., (2008) of IWFM carried out a study on Flood 2007.

Thank you