Knowledge Bank

Bangladesh is a disaster-prone country with an area of almost 1.5 million sq km and a population of 160 million, making it the most densely populated country in the world. It is located at the lowermost part of the basins of the three Himalayan rivers: the Ganges, Brahmaputra and Meghna. The combined watersheds of these rivers are about 1.75 million sq km, of which only 7.5 percent lies in Bangladesh. Around 90 percnet of the runoff is generated outside Bangladesh during a five-month-long rainy season from June to October, while for the other seven months there is almost no rainfall. Huge runoff in a short time associated with huge sediment loads makes managing the risk of flooding more complicated.  Normally about 20 percent of the country is flooded, but in extreme cases about 70 percent of the area of Bangladesh is flooded, creating significant negative impacts on national economy.Water management in Bangladesh is very challenging due to too much of water in monsoon and too little during the dry season. Coastal cyclones and cyclone induced flooding in coastal areas is an added problem. A projected sea level rise of about 80 cm by 2100 will make future water management even more complex and challenging. Bangladesh has a 710 km long coastline and a coastal area that is about 30 percnet of the country’s total area and home of 28 percent of its total population. The total water volume and sediment loads are delivered through the coastal area to the Bay of Bengal. This has severe impacts on water management in the country.Both structural and non-structural measures are adopted for addressing flood risk in Bangladesh. Flood forecasting and warning is the most fruitful non-structural measure to mitigate negative impacts. Using the latest technology to obtain flow data from upstream basins is essential to making flood forecasts with long lead times. Because the watersheds for the Ganges, Brahmaputra and Meghna rivers are shared by different countries in the region, regional co-operation and joint research is essential for reducing flood vulnerability by providing timely and reliable warnings to save people's lives and property.