Flood defences

There are 2 types of flood defences: HARD STRATEGIES: Try to prevent floods from happening in the first place. SOFT STRATEGIES: Let floods happen and try to help people cope with floods.

Which is which? SHOW me what you think: GAME 1: STAND UP, SIT DOWN: STAND UP = HARD STRATEGY SIT DOWN = SOFT STRATEGY GAME 2: TRAFFIC LIGHTS: RED = HARD STRATEGY YELLOW = I DON’T KNOW GREEN = SOFT STRATEGY

Accepting the damage & loss: Often happens in countries which can’t afford to protect against flooding. E.g. L.E.D.Cs such as Bangladesh

Flood plain zoning: Land near the river in the flood zone called the floodplain, can be protected from certain sorts of land use or building. E.g. Floodplain in Camarthen (River Towy / Twyi)

Forecasting flood levels: To give the public warnings about possible flooding. The media or police sirens can be used to warn communities of flooding. E.g. Environment Agency & Met Office, UK E.A’s “flood maps” showing likelihood of flooding

River straightening: The course of the river is straightened, allowing the river to be free from obstructions and to flow faster. E.g. Mississippi E.g. Rhine E.g. Jubilee section of River Thames (London)

Making the channel larger, deeper or wider: To hold more water before it overflows. E.g. Mississippi

Flood insurance Can be offered so people living in flood areas can insure their property against flood damage. E.g. Direct Line House insurance (UK)

Afforestation: Plant trees to intercept the rainwater and delay the time it takes to reach the channel. The roots of the tree will remove some of the water from the soil and bind it together to stop landslides. E.g. Mississippi / Rhine catchment

Dams & reservoirs: Aswan High Dam, Egypt To hold back the water and keep it stored in special lakes called reservoirs, Water is released when it is needed; e.g. in drier summer months. These reservoirs can be used for recreational boats as well as a water supply. Turbines can also be built which will make Hydro-electric Power. These are very expensive, e.g. the Three Gorges Dam in Asia cost $25 billion! It also took a long time to build: many years. Also, many people were forced to leave the area and the habitats of wildlife were flooded upstream of the dam. The Clywedog reservoir was built for regulating the River Severn. Aswan High Dam, Egypt

Walls, banks or levees: A B Artificial and “human” made - can be built on either side of the river. They are common because they are cheap to build. E.g.: (A) Concrete wall - River Towy / Twyi Carmarthen (B) Levees - Mississippi A B

Public relief funds: May be set up after a disaster where charities are set up to collect donations. E.g. after the Lynmouth flood £1,3000,000 had been collected by the summer of 1953.

Emergency procedures: Can be put in place so everybody in the high risk areas knows what to do in the event of flooding. E.g. Environment Agency’s “Floodline” campaign (T.V., leaflets & phone number).

Floodgates Camera monitors high risk areas. Floodgates closed by staff during times when rainfall / flood risk is high. E.g. Village of Abergwili in Camarthen, (Towy Valley). Worcester - a wall of wooden pallets covered in plastic sheeting. These can be erected faster than the water rises!

Flood shelters Flood shelters, often on raised ground, and designed to hold a few hundred or a few thousand people - have flags on roof which are raised to show the warnings. E.g. “Killas” in Bangladesh cs.gazetteonline.com/.../archive/2007/7/23.aspx Flckr st martins public

Coastal barriers: A To prevent coastal inundations by cyclones. E.g. (A) Netherlands/ in Bay of Bengal in Bangladesh. However, they are expensive, and can't protect all the small islands and chars. A

Flood / Tidal Barrages & coastal barriers: In the lower course of the river. Designed to control water flow in the delta – however it could make local situation worse. E.g: (A) Swansea Barrage (River Tawe) (B) Thames Barrage (London) Coastal barriers are an expensive way of preventing coastal inundations by cyclones and “storm surges” E.g. (C) Netherlands/ in Bay of Bengal in Bangladesh. A B C

Drainage / flood relief channels: Built to drain and store water in areas liable to flood. E.g. River Exe (Exeter) E.g. “water meadows” alongside the Rhine.

Widen bridge arches / change design Make bridge arches wider so that debris (e.g. fallen trees) doesn’t not clog up & cause a damming effect. Bridge supports not in the river, but on the banks either side so they don’t interfere with water flow. E.g. Carmarthen

Plan building House built on stilts (e.g. Bangladesh) Buildings raised above floodplain

Sand-bagging Bags of sand placed outside doors of houses to try and “flood-proof” them and delay entry of floodwater. Sandbags placed on either side of river.