Managing Rivers and Flooding

Short Term

• Sand bags - to prevent further damage to property

Medium Term

• Afforestation - trees are planted to absorb water (additional information)
• Managed flooding - the river is allowed to flood in some places to avoid destruction close to large settlements
• Planning - governments and local councils implement plans to help prevent damage to property in future

Long Term

• Dam building - dams are built in order to control the amount of discharge released
• River engineering - the river channel may be widened or deepened to allow water to flow more quickly

The values and attitudes of interested groups

Environmental groups and residents often prefer options which have as little impact on the settlement and environment as possible, such as planting trees

Governments and investment groups often prefer hard engineering options, such as dam building, as this can often generate large profits and can also attract people for leisure purposes such as sailing.

This video explains what can be done to prepare for flooding

Case Study - River management - the Mississippi

This video looks at the Mississippi river is a major river covering almost half of the USA. The river used to flood and the channel moved around the floodplain. This made navigation difficult so people attempted to manage the river. Strategies involved dykes, levees, dams and river straightening. This solved the flooding problem as the river flowed faster over a shorter distance. In 1993 the management techniques failed and large areas flooded. People now question whether or not we can control natural processes.

Flooding in MEDCs

Flooding in MEDCs has a different impact to flooding in LEDCs. A large amount of housing in urban areas of MEDCs has been built on flood plains. This has obviously led to extensive flooding in many MEDCs (for example, Mississippi river, USA or River Severn, UK).

The floods are often caused by the amount of tarmac and other impermeable surfaces which have been laid down as a result of urbanisation. This leads to rapid overland flow and rivers reaching their peak discharge rapidly in times of heavy rain and leads to extensive flooding.

Emergency services and warning systems mean that loss of life in MEDCs is often small. Homes and businesses, however, are often damaged and the cost can be great (the Mississippi floods of 1993 caused $10 billion of damage).

Plans to prevent flooding are often only put in after a flood has occurred. However, as MEDCs are more economically developed, they are able to implement effective strategies to reduce the damage from flooding in the future.

Case Study - Flood defence - dyke construction on the River Waal

This video looks at the River Waal in the Netherlands is naturally broad and shallow. Meanders along the river have been straightened through channelisation. Dykes have been built along the bank to encourage the water to flow faster in the middle of the channel, enabling better navigation. The river used to flood, which created alluvium-rich floodplains for farming. River defences were built to contain the river, but these were breached when the flooding problem became much more severe.

Flooding in LEDCs

Flooding in LEDCs has a massive impact on the economy, health system and people. The floods can occur due to monsoon rains, snow melt in spring or just unusually high rainfall (for example, River Ganges, Bangladesh).

Loss of life may be great as emergency services struggle to cope with the vast amount of help that is needed. Communication links are often destroyed and as the quality of housing is often of a poor standard, many homes are completely destroyed leaving people homeless.

Due to the lack of provision for clean up operations, water often remains stagnant which leads to the rapid spread of water-borne diseases, such as cholera and typhoid.

LEDCs may need to seek aid from MEDCs to assist with the damage caused by severe flooding.