Economics Discipline Khulna University – 9208, Bangladesh Md. Firoz Ahmed Assistant Professor Course Code: Econ 5217 Course Title: Climate Change and Disaster Management 1Econ 5217_ Lec # 04_Firoz Ahmed

Flood A normal condition of the hydrological cycle is perceived by man-due to its negative impacts on life and property – as abnormal, and labeled as flood. Flood – Unwanted inundation of land, which can damage crops, homesteads, and infrastructure, disrupt economic activities and endanger the lives of people and their domestic animals. Heavy or prolonged rainfall 20-22% of the country is flooded even in a year of normal precipitation 80% of the country is considered as flood prone Econ 5217_ Lec # 04_Firoz Ahmed2

On the basis of flood depths, five types of flood Land typeDescriptionFlood Depth Nature of Flooding F0HighlandNot floodedIntermittent or flood up to 30 cm F1Medium Highland 30 to 90 cmSeasonal F2Medium Lowland90 to 180 cmSeasonal F3LowlandOver 180 cmSeasonal (>9 months) F4Very LowlandOver 180 cmSeasonal (>9 months) or perennial Econ 5217_ Lec # 04_Firoz Ahmed3

Floods with the Affected Area Year Area Affected (%) Year Area Affected (%) Econ 5217_ Lec # 04_Firoz Ahmed4

Probable Return Period of Floods and Affected Areas Return Period (in Years)Affected area (% of the country) Around Around 70 Mean22 Econ 5217_ Lec # 04_Firoz Ahmed5

Causes of floods Short – term Causes Heavy monsoon rain resulting in deluge Synchronization of peak flows in the major rives, causing drainage congestion in the mouth Strom surge due to tropical cyclones in the Bay of Bengal Econ 5217_ Lec # 04_Firoz Ahmed6

Long – term Causes Construction of dams upstream Embankments Rising river beds caused by deposition of silt River bank-erosion and changing river courses Deforestation in the upstream areas Global warming Unplanned development and urbanization Seismic (Earthquake) and Neo Seismic (Earthquake) and Neo- -tectonic Activities Lack of coordinated flood and water management policy among catchment counties Causes of floods Econ 5217_ Lec # 04_Firoz Ahmed7

Types of Flood Flash flood River or monsoon floods in the major river Rain water or local flood Tropical cyclones in the Bay of Bengal Econ 5217_ Lec # 04_Firoz Ahmed8

Floods due to human intervention: Breaching of an embankment – difference of water level between river (out side embankments and land area) Public cuts in flood protection embankments – people willingly cut the embankments to protect themselves form water logging and others Cuts in coastal embankments project polders – Shrimp farmers cut the polders to allow brackish water onto their land. Release of water from a dam – Heavy rainfall cause danger for water reservoir and then it requires rapid releases. Ponding of water behind road, railway or flood embankments – inadequate provision of drainage Types of Flood Econ 5217_ Lec # 04_Firoz Ahmed9

Flood Action Plan In components and 15 supporting activities Argued in favor of – Embankments for the countries rivers Location of Embankments close to the rivers Flood control / mitigation is an international responsibility Econ 5217_ Lec # 04_Firoz Ahmed10

Criticism of FAP (Flood Action Plan) Form the very outset it was a topic of public debate Criticisms - Technical Viability of the Embankments (Embankments could rise flood level outside the embankments and thus river bed rise.) Agriculture (embankments would prevent fertile silt supply to croplands) Wetlands and biodiversity Involuntary resettlement (land acquisition for flood protection, displace the habitat, thus some people may unemployed) Public participation Institutional capacity Econ 5217_ Lec # 04_Firoz Ahmed11

Flood Management Methods Structural Method – Embankments (though it has many drawbacks) Drainage and Channel improvements (though it is not considered economically for the entire reach of the river. River training – build some structure Non-Structural Methods- Flood forecasting and warning system Flood Proofing – awareness and education, training to people, Flood preparedness - Normal time, Alert and warning stage, Disaster stage, Rehabilitation stage. Flood plain zoning - Econ 5217_ Lec # 04_Firoz Ahmed12

Reference Book Rasheed, K.B.Sajjadur, Bangladesh: Resource and Environmental Profile, AHDPH, Dhaka Econ 5217_ Lec # 04_Firoz Ahmed13