Coastal Flooding

Reasons for rising sea level:

• Last 15 years global sea level has risen 3mm each year
• main cause of rise is due to thermal expansionof seawater as more heat is absorbed
• Melting of ice on land e.g. from greenland/Antarctic ice sheets.  Removes water stored in a frozen state on land and enables it to flow into sea which increases amount of water in sea. Causes from this is global warming, increase in carbon dioxide in human activities.
• Rising sea levels will have important consequences for people living in the coastal zone. 

Location

• Lower Thames estuary, London

Background

• 1953 storm surge, funnelled down North sea killing 300 people. High spring tides and strom surge=flooding
• River thames has large tidal range- in excess of 7m on spring tides. Tidal surges occur when a combination of high tide, easterly winds and a weather system depression over the North sea- cvasuing tide levels to increase way above normal range

Potential Impacts

• Economic- property worth £100 billion at risk. Very high infrastructure costs. 'City of London' financial headquaters will be affected and jobs could be lost. Industry, housing anf farmland all at risk.
• Social- 1.25 million live in the Thames flood zone- jobs, healthcare, schooling, travel could be impacted upon. e.g. 69 London tude stations, 400 school and 16 hospitals in flood zone. 
• Political- Houses of Parliament at risk. Cost of defences/future plans part of government policy.
• Environmental- low-lying mudflats and salt marshes could be lost. Loss of land. Loss of habitats for birds such as oystercatchers, terns and egrets.

Measures to reduce flood risk- as a result of 1953 flood, a system of flood defences was constructed, largest being the Thames Barrier/Barrage. Built 1974-1982. Costs £534 million (£1.6 billion todays pricing). Raised 4-6 times a year.

Up to 2009, closed 116 times. Currently protects buildings worth £100 billion. It will probably need to be replaced in the next 30-50 yeras. A 16km wide barrier may be needed (stretching from Kent to Essex.)