Presentation on current gaps in flood management Presentation on current gaps in flood management Presentation on current gaps in flood management Presentation on current gaps in flood management

1. PRESENTATION ON CURRENT
GAPS IN FLOOD MANAGEMENT
Sheikh Fahim Faysal Sowrav
Email: sffsowrav@teachers.org

2. INTRODUCTION
Coastal zone flood management has very important bearings
in Bangladesh since coastal population is around one-fourth
of the country population, with poor livelihood groups
forming about three-fourths of the coastal population.
The development/livelihoods have been adversely affected by
natural hazards such as tropical cyclones and associated
storm surge floods, tidal flood, river erosion, sea beach
erosion, arsenic contamination of groundwater, drainage
congestion and water logging, saline water intrusion, soil
salinity, conflict between shrimp farming and rice
cultivation, scarcity of freshwater due to reduction of inflow
to the rivers and degradation of ecosystems.

3. TIDAL FLOOD
 The coastal area of Bangladesh belongs to the ‘Principal
Lunar Semi-Diurnal Constituent’ that faces two tides and
two ebbs in every 24 hours.
 On the other hand, a ‘Perigean Spring Tide’ is a tide that occurs
three or four times a year when the Moon's perigee (its closest
point to Earth during its 28-day elliptical orbit) coincides with the
Spring Tide (when the Earth, Sun and Moon are nearly aligned every
two weeks).
 This lunar affect increases the tide at least 20% higher than
the normal and inundate more coastal areas for long
duration but draws (almost) nobody’s attention.

4. STORM SURGE FLOOD
 Most of the Storm surge flood occurs during the pre monsoon
(April/May/early June) and post monsoon (late
Sept./October/November) period.
 Major coastal flooding typically occurs in response to strong
onshore winds, barometric pressure changes from a coastal storm
and heavy rainfall in the coast.
 If a storm strikes during a Perigean Spring tide, flooding could be
significantly worse than it otherwise would have been.
 The process relatively complex and need combined attention of
Meteorologist, Hydrologist & Modeler.

5. CURRENT GAPS
• No forecasting system available for Tidal flood/Storm surge flood;
Bangladesh Meteorological Department issues tide height
forecast (which is in addition of normal astronomical tide height) with Cyclone
forecast.
• Weakness in tidal data, storm surge data and wind speed data
collection (frequency & quality).
• Existing flood forecasting model (MIKE 11ff) used by FFWC of
BWDB has limitation to address tidal flood/storm surge flood.
• Tidal flood/Storm surge flood is a combination of Meteorological &
Hydrological Phenomenon; strong coordination/collaboration not
yet established

7. 7
Flood Proofing through Raising
Homestead Plinth Level
(Individual)

8. SUCCESS STORY AT THE END
Cyclone
Name
Date Wind Speed
on Making
Landfall &
Category
(Saffir/Simp
son Scale)
Estimated
Tidal Surge
(in M)
Deaths
BHOLA 12 Nov 1970 185 Kph Cat
3
6-9 300-500,000
GORKY 29 April
1991
250 Kph Cat
4
6-7.5 138,000
SIDR 15 Nov 2007 240 Kph Cat
4
3-5 4,234
NARGIS 02 May 2008 215 Kph Cat
4
3-4 150-
1,000,000

9. CONCLUDING REMARKS
• Reducing risks of water related hazards are important
determinants of economic growth and social prosperity in
the coastal zone of Bangladesh.
• There is a need to combine “high tech” use of satellites and
computer modelling to determine the potential threat
emanating from a particular weather system.
• Flood Management decisions can not be successful without
giving due consideration to interdependence of land, water,
ecosystems and infrastructures.
• Related institutions, available tools, techniques and
knowledge needs to be combined together to address the
problem.

10. 10
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