Aims of today’s session<br />To understand and appreciate the difference between human and physical causes of flooding<br />To look at Bangladesh as a case study and separate human from physical factors<br />To analyse and create an essay plan.<br />
Activity<br />Drawing a Venn Diagram like this and add the effects to each side and think of one’s that could be said to be both human and physical<br />Both<br />
Bangladesh is a country in SE Asia that suffers annual flooding<br />The floodwaters bring alluvial sediment which makes the delta and floodplains very fertile<br />Floods frequentlysevere causing loss of life and economic damage<br />Extreme poverty and geographic pressure increase the suffering<br />Much of the country´s budget must be used for recovery<br />
The flood hazard is due to its geography: the country is one huge delta<br />Floodplain contains 250 perennial rivers, of which 56 originate outside the country (Tibet, Bhutan, India and Nepal)<br />Only 7,5% of the total catchment area is within the country and 90% of discharge originates elsewhere<br />
There are Three main rivers in Bangladesh<br />The Ganges, whose lower course is known as the Padma / basin area 1,1 million km, lenght 2478 km, average maximum discharge 299 000 cumecs<br />The Brahmaputra, whose lower reaches are known as the Jamuna / basin area 0,9 km, lenght 2900 km, average discharge 317 000 cumecs<br />The Meghna, east of the Padma-Jumana area, lenght 800 km, half of which lies in Bangladesh <br />
Types of Floods in Bangladesh<br />Flash floods carry a heavy sediment load, raising the level of river beds, and are caused by heavy monsoon rains falling on mountains and hill next to the floodplain<br />River floods occur between May and September as a result of heavy regional storms or melting of the Himalayan snowpacks<br />Rainfall floods result from localised precipitation during the monsoon rains, mostly in low-lying areas<br />Cyclonic floods are sea floods and occur when cyclones from the Bay of Bengal create a storm surge which moves inland<br />
The human causes of the floods<br />Deforestation<br />Dam building<br />Urbanization<br />Global warming<br />
Solutions to the flood hazard<br />Flood action plan 1990-1995 sponsored by World Bank involving: <br />Surveying all main rivers and flood areas,<br />raising embankments on west bank of the Brahmaputra. <br />Upgrading of embankments on the east bank. <br />five projects using mathematical models and remote sensing to model drainage basin flows. <br />Studies of economic, enviromental and social problems<br />Flood forecasting<br />increaseradar stations in the hills and developing links to a flood forecasting centre<br />Controlled flooding where landcan receive flood waters through sluice gates<br />Coastel embankments and polders (low-lying tract of land enclosed by embankments )<br />
Self-help “flood-proofing“ which means the development of irrigated agrivulture during the dry season to avoid the monsoon risk , plus escape centres o high ground, specially designed school buildings, elevated roadds and market-places.<br />Dredging the channels- but this is too expensive and the channels would soon become choked again in one season.<br />Special bunds (embankment) to protect the capital city Dhaka<br />Dam construction upstream and groundwater abstraction to crceate storage in the soil for monsoon rains<br />
The short-term response to the floods:<br />By the Bangladesh government<br />Distributed money and 400 tonnes of rice<br />Provided relief supplies of fresh water and sanitation services<br />Appealed for national unity and calm in the wake of the disaster and the general strike which took place in response to the flooding and accusations that the government failed to get basic goods to the people affected<br />
By the governments of other countries<br /> Many countries around the world gave aid to Bangladesh during the flood disaste. Some of the donors included:<br /><ul><li>The UK with steel bridge materials and 100 000 million tonnes of wheat
Canada with 12500 million tonnes of wheat and money for medicines, water tablets, house repair, sanitation and for rehabilitation of farming and fishing
Saudi Arabia sent tw cargo planes with food, medicines, blankets and tents</li></li></ul><li>By The Disaster Forum (a network of aid agencies)<br />Provided boats to rescue people and move them and their belongings to higher land<br />Supplied medicines to treat and prevent the spread of diseases<br />Médecins Sans Frontiéres used six mobile teams in boats to travel around in one district where the population was literally living on the water<br />Supplied clean drinking water by repairing wells<br />Monitored the health situation and set up a mmedical treatment centre<br />Distributed fodder for livestock<br />Distributed food, plastic sheeting and water purification tablets<br />Planned a rehabilitation programme to repair and construct housing and sanitation<br />
Conclusion<br /> Managing the flood hazard is a challange for government and hydraulic engineers. In Bangladesh there is still uncertaintly over the main causes of the flood hazard, and further research is required to identify important factors and the effects of proposed structural solutions. Building embankments and bunds is particularly controversial: they can prevent floodwaters draining from fields and back into rivers, and they have an impact on fish stocks, a vital resource in a country where 5 million depend on fishing for their livelihood.<br /> Bangladesh faces triple problems in the future: sea level rises, delta subsidence and reduced delta growth. The net effect by 2100 could be a 3 metre rise of the sea level and a 2 km retreat of the shore, resulting in a 26% reduction of habitate land with 27% of the population displaced and GDP reduced by two-thirds.<br />
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