Basin-wide approach to flood risk management in Bangladesh

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Mohammad Hossain, Mohammad Hossain

Friday 3 july 2015

12:36 - 12:39h at Oceania Foyer (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flooding along in rivers and coasts, Poster pitches

Parallel session: Poster pitches: 15L. Flood Risk - Flooding

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Bangladesh is a disaster-prone country having an area of only 1,47,570 sq. km. with a huge population of about 160 million that makes it the most densely populated country of the world. The country is at the bottom of the basins of the three Himalayan Rivers: the Ganges, the Brahmaputra and the Meghna (GBM). The huge volume of runoff and sediment load generated from the GBM basin of about 1.75 million sq. km. area is delivered to the Bay of Bengal through a few rivers of Bangladesh. Around 85% to 90% of the flow is generated outside the Bangladesh territory and only about 10 to 15% is generated within Bangladesh. In normal flood about 20% of Bangladesh’s territory is inundated while in extreme cases about 70% area is vulnerable to flood disasters which have significant negative impacts on national economy. Records show that during devastating floods of 1987, 1988, 1998 and 2007 the flood affected area of the country was 39%, 61%, 68% and 42% respectively. Water management in Bangladesh is very challenging due to too much of water in monsoon (June to October) and too little during the dry season (November to May). Coastal cyclones and cyclone induced flooding in coastal area is an added problem during April-May and October-November period. Future anthropogenic changes in the hydrological cycle due to climate change and construction of dams and barrages in combination with increasing water demands in the GBM basin will make future water management even more complex and challenging in downstream Bangladesh. Flood induced disaster and risk cause huge loss of lives and properties. Flood management and risk reduction practices in Bangladesh have continuously evolved in last 60 years, in different phases. Initially, the emphasis was on structural measures through the implementation of large-scale flood control, drainage and irrigation (FCDI) projects in late 1950's and 1960's. In early 1970's and afterwards, flood management shifted to small and medium scale FCD projects to provide early benefits. Thereafter, during mid-eighties and afterwards, environmental protection came to the forefront gradually. However, as the flood prone area of the country is large, only structural measures alone could not mitigate flood problems; as a result non-structural measures such as flood forecasting and warning were later incorporated. Based on the new concept of disaster management, a balanced importance to both structural as well as non-structural mitigation measures is given. Flood Forecasting & Warning Centre (FFWC) of Bangladesh Water Development Board (BWDB) in association with Institute of Water Modelling (IWM) developed a comprehensive system of collecting and processing hydrologic and other data as input to forecasting models; preparing flood forecasts and warnings on a daily basis during the flood season. The forecast incorporate new technologies that increase the accuracy and reliability of flood forecasts and provides real-time flood information and early warning with lead-times of 24, 48 and 72 hours. Updating of the flood forecasting system is going on to cope with modern hydrological data collection system, advancement of weather forecasting and overall higher expectation of warning information. As the GBM basins are shared by different countries thus data sharing and regional co-operation in hydrological activities and research is an essential prerequisite for reducing flood vulnerability by providing timely and reliable warning to save people's lives and property in Bangladesh. Keywords: Bangladesh, Floods, Satellite based flood forecasting, regional cooperation