Rivers

CASE STUDIES

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  • Created by: Louise
  • Created on: 07-05-11 20:54

BOSCASTLE FLOODS 2004

CAUSES - PHYSICAL - heavy thundery precipitation - 200mm in 24hrs, cold front (low pressure) mild winds along coasts, high ground, small catchment area, confluence (Rivers Valency & Jordan), narrow channel

HUMAN - deforestation, farming - harvest season, lack of flood defences, old drainage system, structures obstructing the course of the river

EFFECTS - ECONOMIC - 4 million insurance claims, businesses were not all insured for lost trade, tourism was devasted - 1 milliion people visit N.Cornwall each year bringing £225 million to the economy, jobs provided to build the new flood prevention scheme (£900,000)

SOCIAL - Homelessness, homes destroyed, diseases spread via burst sewage pipe, communication problems - stress, property and poccession loss/damage, financial insecurity, community support, unaccessible village services

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BANGLADESH FLOODS 2004

 monsoon season, tropical cyclone brought strong winds, no slopes for surface runoff, rivers eroded levees which collapsed

shallow river channels, deforestation reduced infiltration and interception, soil erosion reduced river capacity, rise in sea level

high death rate (800 people), water borne diseases (cholera),  damage to crops, livestock death, loss of land (800,000 hectres of agricultural land) homelessness (36 million people)

10,000 volunteers produce warning to help with evacuation, broadcasts over loud speakers, cyclone shelters built - FOREIGN AID = UN AGENCIES

RIVERS - GANGES, MEGHNA, BRAHMAPUTRA

DAMAGE - $2.2 billion

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HARD ENGINEERING - THREE GORGES DAM, CHINA

BUILT TO REGULATE THE RATE OF WATER PASSING IN THE RIVER

Located on the Yangtze River, providing HEP for central and E.China

Reducing flooding for 15 million people.  The dam itself is 2.3km long and 100m high

Cost £25 billion

1.2 million people resettlement. 

increased erosion down stream, afforestation is needed to stop sediment being washed into the river,

possible increase in landslides and habitats for wildlife will be disturbed.

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SOFT ENGINEERING - RIVER QUAGGY, UK

SOUTH-EAST LONDON

1960's - culverts and artifical channels built underneath Greenwich and Lewisham - continual urban development - increasing flood risk

Sustainable approach was accepted

bringing the river above ground and running through Sutcliffe Park - creating a functional open space

The park was lowered and shaped to be a floodplain - flood storage capacity 85,000m3 of water and reduced the risk of flooding for 600 homes/businesses

created a wetland environment for wildlife, reedbeds and wild flower meadows

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