Flood Risk Management and Urban

Resilience in Bangladesh

Institutional Setup of DNCC

Institutional Setup of DNCC

1. Ministry of Local Government

2. Secretary of Local Government

3. Administrator

4. Chief Executive Officer

5. Chief Engineer

6. Additional Chief Engineer

7. Superintending Engineer

8. Executive Engineer

9. Assistant Engineer

10. Sub- Assistant Engineer

11. Road Inspector

Institutional Development

• Following the floods of 1987 & 88, the

Government has undertaken FAP studies

• National Water & Flood Management Strategy

• National Water Policy

• National Water Management Plan

• Guidelines for Participatory Water

Management

Meghna Basin

82,000 sq.km

Brahmaputra Basin

552,000 sq.km

Ganges Basin

1,087,000 sq.km

B A Y O F B E N G A L

BHUTAN

I N D I A

C H I N A

BANGLADESH

I N D I A

Bangladesh rivers receive runoff from a catchment of 1.72 million sq.

km, around 12 times its land area

Impacts on Land and Water Management

Water ~ Land Sector

Flooding Cyclonic

surge Drought

Salinity

intrusion

River

erosion

Climate Change

Temperature

change

Precipitation

change

Sea level

rise

Glacier

melt

FFWC produce monsoon flood

forecast with a lead time of 24, 48, and

72 hours

The center collects available

qualitative weather forecast, and

incorporate them in the mathematical

model called FFWC Super Model

The Super Model is based on data &

information of 1998 or earlier

Since, modeling technique as well as

Flood Forecasting is an evolving

technology, it needs continuous

upgrading & updating including

training of relevant professionals.

Introduction

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0 2200.0 2400.0 [m]

0.0

5.0

10.0

15.0

20.0

25.0

30.0

P5-2 0 - 1963

1963

GANGES-EXT 7370 - 6820

6820

7370

[meter]

-5.0

-10.0

-15.0

Lowest point in cross section

Flood Map for 1-in-10 Year Return Period Flood in 2050 without any climate change

Flood Map for 1-in-10 Year Return Period Flood in 2050 under climate change conditions

Mathematical models have been used to identify drainage problems, plan and design an effective drainage

system for the pourashavas

Primary drain Secondary drain

Godagari

Dohar

Primary drain (7 nos): 9.3 km

Secondary drain (11 nos): 7.4 km

Primary drain (6 no): 18km

Secondary drain (39 no): 33km

D. Response Modeling A. Economic & Urban Growth Modeling

B. Flood Modeling C. Damage Modeling

FLOOD MANAGEMENT

STRATEGIES

Flood Map for 1-in-10 Year Return Period Flood in 2050 under climate change conditions after implementation of adaptation measures

A. Drivers of Flooding: Urbanization is changing the

natural drainage system. Economic growth model and

urban growth model helps us to formulate the future

scenarios better.

B. Flood Modeling: New state of the art technology can

simulate the depth, duration, velocity of flooding with high

accuracy for a complex urban system.

C. Flooding Impact: Damage in building structures due to

flooding can be determined using flood map, damage

curves and GIS.

D. Strategies for Flood Management: Different strategies

can be evaluated and Flood Resilience Index (FRI) can be

developed based on physical, social, institutional

dimensions.

IWM conducted a study to assess the impact of climate change on Khulna drainage system. Outputs from GCMs were applied on several models to determine the damage due to flooding for several climate and socioeconomic scenarios. Adaptation measures were proposed which would reduce flooding.

Field Survey

Stakeholder Consultation

Water Resources Planning Division

Flood Management Strategy

Economic & urban growth modeling.

Flood modeling.

Damage modeling.

Response modeling.

Flood management with advanced Analytical tools.

A. Drivers of Flooding : Urbanization is chinning the natural drainage system.

Economic growth model and urban growth model helps us to formulate the

future scenario better.

B. Flood Modeling : New state of the art technology can simulate the depth,

duration, velocity of the flooding with high accuracy for a complex urban

system.

C. Flooding Impact: Damage in building structures due to flooding can be

deterring using flood maps, damage, curves and GIS.

D. Strategies for Flood Management: Different strategies can be evaluated

from flood resilience Index (FRI) can be developed based on physical,

social, institutional dimensions.

Indian Data

WMO

JRC

WARPO

FFW C Radio Tower

FFWC Satellite dish

24, 48, 72 hr

forecasts

water level

flood extent

maps

thana

inundation

maps

Telephone

Fax

Fax Modem

ModemTelevision

Bulletine

GIS data layers

Radio

wire

less c

om

mu

nic

atio

n

via modem

manual entry

Te

lem

etry

/Da

ta b

ox / V

oic

e SPARRSO

Sattelite images

BMD

Weather forecast

Synoptic charts

Boundary estimation

Rainfal,

Water level

Data Entry & Processing Modelling & Mapping

River stage

Rainfall

R

e

a

l

T

i

m

e D a t a

Dissemination

to the public

Dissemination

to various agencies

Internet

Increase the Lead-time of Forecast

Present

Expected

10-day forecast

20-day forecast

Floods differ in

location timing

intensity

duration

Floods are of four types:

a) River floods

b) Rainfall floods

c) Flash floods

d) Tidal floods.

Urban flood management using Flood Forecast

Pump operation

Structure operation

Detailed forecast inside

the city area

Emergency maintenance

of flood dyke

- Drainage Projects

- Flood Control

- Flood Control &

Drainage

- Flood Control,

Drainage & Irrigation

- Irrigation & Drainage

- Irrigation Projects

65% of flood prone

lands now under flood

management

Flood Management

Normal Flooding

Extreme Flooding

Depth Duration Mapping

Duration Mapping

Flood Mitigation Structural measures

• Embankments

• Hydraulic Structures

Non-structural measures

• Flood forecasting and dissemination

• Flood preparedness, etc.

What has been done to reduce the huge losses of lives and properties?

The concept of mathematical modeling has been introduced for improved flood management through understanding the problems scientifically and to devise appropriate, efficient and cost effective mitigation measures.

Non Structural Measures

Flood Forecasting and Warning System

in Bangladesh

What has been achieved so far?

Non-structural measure

Established a Flood Forecasting and

Warning Centre

Dissemination of warning through

Government and NGO initiatives

Taking decisions regarding early harvesting to avoid major crop damage

Planning of transplanting of rice crops

Taking protective measures for saving assets and livestocks

Taking precaution for culture fisheries

Planning flood response activities

Taking precautionary measures to protect infrastructures (growth centres,

food silos, embankments, Roads etc.)

• Taking preventive measures against water borne diseases

What people wants?

Medium-range flood forecasts (4 – 14 days)

Flood Management – Non Structural Flood Forecasting with increased Lead-time

CFAN FFWC

Mode of Flood Forecasting in Future

Forecasting with 10-day Lead-time (CFAN, on-going)

Seasonal Forecasting

Low Flow Forecasting

• Flash flood occurred in April 2004 in the

northeastern region of Bangladesh is the ever

worst in the recorded history.

• Flood 2004 mainly occurred in the Brahmaputra

and the Meghna basins.

• FCD schemes could achieve its primary goal

• Increasing intensity of floods calls for changing

design criteria

Observations

Lessons Learnt

Safety could be provided for floods of even very high frequency

Concept of compartmentalization may be replicated with the community participation

Coastal embankments and drainage structures are very successful

Drainage congestion at some coastal polders due to siltation of the outfall channels.

Decision support systems for monitoring of flood management systems.

Decision support systems (DSS) would help in close monitoring of flood management systems

Lessons Learnt

The magnitude of this year’s flash flood could

have been reduced, if the conveyance

capacity of the river systems could have been

increased by taking up appropriate measures.

Bridges and culverts should have adequate

clearance for navigation.

Flood proofing measures, where feasible, may be

implemented to reduce the flood damage.

• Rationalising of Existing FCD Infrastructure” need to be taken

• Flood risks zones should be designated

• Safe conveyance of the large cross-boundary flows by channelising and stabilizing these rivers with appropriates measures

• Excavation and desilting of rivers, khals, offtakes of distributaries etc

• Rivers, khals and floodways may be kept free from encroachment for free flood flows.

• Full flood protection and proper drainage for the urban areas

Recommendations

• Required fund may be ensured for the maintenance

• Revolving fund for emergency flood fighting

• Coordinated planning, design and construction of all rural roads, highways and railway embankments

• Adequate on-the-spot security for the personnel engaged in flood fighting

• Legislation to regulate the community participation in O&M activities

• Water Act may be enacted to regulate all water management activities

• Improved flood forecasting system

Recommendations

Reassess and redesign of the flood embankments including submergible

embankments in NE region.

An integrated approach of river management covering dredging of the

navigational routes and river bank protection along with feasible

interventions can be undertaken.

Redesign the National Highways, Railways and other key infrastructures

etc.

Reassessment of SW and GW resources considering climate change

scenarios and formulation of plans and incorporation in NWMP

Way forward

Way forward

Development of early warning of storm surge inundation forecasting.

Reengineering of the coastal polders by phases for Sea level rise and

storm surge for the safety of life and livelihood of coastal community.

There are need of new cyclone shelters in the newly defined high risk

areas specially in the Barisal and Khulna division.

Development of GW modelling to understand and manage salinity

intrusion for water management in the coastal region.

There are knowledge gaps right from downscaling of the climate model to the

considerations of glacial melt or blending of meteorological science with the

hydrology. Capacity building in these areas will be of prime importance.

Regional cooperation at the basin level for prediction of climate change impacts

and adaptation measures, sharing of knowledge and development of resources

(conservation of water through upstream reservoirs, flood moderation and

forecasting, navigation, hydro-power etc.)

The existing Bay models are capable of forecasting storm surge induced flooding.

These models extend from Indian to Myanmar coast. These models can for the

basis for regional cooperation

Way forward

Thank You