Case Study: Flooding in Bangladesh- Ganges Delta

• 6000m peaks of Himalaya Mountains receives snowfall as the main precipitation. In April and May higher temperatures cause the snow to melt releasing silt down the 2500km channels until it reaches Bangladesh where it provides fertile alluvial sediement for rice and wheat lands of Bengal the Golden
• The monsoon season lasts from June to September is intense and prolonged with about 300-400mm of rain which increases surface runoff, with less infiltration which increases the flood risk

• Straightening of the river channel moves flooding risk downstream. Farraka Dam holds water in dry season and releases it in wet season, river can't hold the water and bursts its banks and flooding the levees which has extended the flood season
• Nepal has a land clearance of 1.7% a year leading to more discharge in the Ganges resulting in less infiltration causing flood risks
• Land clearance in Bangladesh in 3.3% a year especially in the Meghalaya Hills which has increased the flood risk as there are less trees to intercept water and so more surface runoff
• In 2008 Bangladesh had a popn. of 146 million people resulting in urbanisation such as in Dhaka- permeable surfaces were replaced with impermeable surfaces and so there was less drainage increasing surface runoff and so water was flowing increasing the flood risk
• If global warming raises seas levels by 30-50cm Bangladesh could be at risk due to its low lying coast leaving it more vulnerable to flooding

People

• 800 died from drowning in floods in 1998
• 2 million homeless becoming refugees
• Social disruption
• 100 died by illnesses from dirty water such as typhoid and diarrhoea

Property

• 300,000 homes destroyed in cities and rural areas
• Many businesses and buildings destroyed
• Food crops washed away and livestock drowned
• 11,000km of road washed away- lots of bridges also collapsed damaging transport links and exports

Land

• Shifting river channels
• Chars destroyed where people lived