Flooding and Management

Flooding and Management

1. Global Warming

   • Global sea level is rising at a rate of about 2mm per year (20 cm in the past century). It is predicted to rise about 18-59cm by 2100 as a result of global warming ( a rapid increase in the global temperature over the last 100 years)
   • The melting of ice on land (e.g. the Antarctic) causes water that's stored as ice to return to the oceans. This increases the volume of water in the oceans and causes sea levels to rise.
   • Increases global temperature causes the oceans to get warmer and expand (called thermal expansion). This increases the volume of water causing sea levels to rise.

2. Impacts of Flooding

   • Economic
     • Loss of tourism.
     • Damage repair.
     • Loss of agricultural land - seawater has a high salt content. Salt reduces soil fertility so crop production can be affected for years after a flood.
   • Social
     • Deaths
     • Water supplies affected - floodwater can pollute drinking water with salt or sewage.
     • Loss of housing.
     • Loss of jobs - coastal industries may be shut down due to damage of equipment and buildings (e.g. fishing boats may be destroyed).
   • Political
     • The government has to make policies tor educe impacts of future flooding by doing things like building more or better flood defences or they can manage the use of areas that might be flooded (e.g. by stopping people living there).
   • Environmental
     • Ecosystems affected - increased salt levels can damage or kill organisms in an ecosystem.
     • Vegetation killed by water - the force of floodwater uproots trees and plants and standing floodwater can drown them.
     • Increased erosion - a large volume of fast-moving water can erode lots of material, damaging the environment.

3. Hard Engineering

   • Man-made structures built to control the flow of the sea and reduce flooding and erosion.
   • Sea Wall
     • A wall made out of a hard material (e.g. concrete) that reflects waves back to the sea.
     • Prevents erosion of the coast and acts as a barrier to prevent flooding,
     • Creates a strong backwash which erodes under the wall. Very expensive to build and maintain.
   • Rock Armour
     • Boulders that are piled up along the coast.
     • They absorb wave energy to reduce erosion and flooding. Also are fairly cheap.
     • Boulders can be moved around by strong waves so need to be replaced.
   • Groynes
     • Wooden or stone fences that are built at right angles to the coast. They trap material transported by longshore drift.
     • Groynes create wider beaches which slow the waves which gives greater protection from flooding and erosion. They are fairly cheap.
     • They starve beaches further down the coast of sand, making them narrower which don't protect the coast as well, leading to greater erosion and floods.

4. Soft Engineering

   • Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.
   • Beach Nourishment
     • Sand and shingle from elsewhere (e.g. the offshore seabed) is added to the beaches.
     • Creates wider beaches which slow the waves giving greater protection from flooding and erosion.
     • Taking material from the seabed can kill organisms like coral. It is very expensive and has to be constantly repeated.
   • Dune Regeneration
     • Creating or restoring sand dunes by either nourishment, or by planting vegetation to stabalise the sane.
     • Sand dunes provide a barrier between the land and the sea. Wave energy is absorbed which prevents flooding and erosion. Stabilisation is also cheap.
     • Protection is limited to a small area and nourishment is very expensive.
   • Marsh Creation
     • Planting vegetation in mudflats along the coast.
     • Vegetation stabilises mud flats and helps to reduce wave speed and creates new habitats for organisms.
     • Isn't useful where erosion rates are high as the marsh can't establish itself. It is fairly expensive.
   • Managed Retreat
     • Removing an existing defence and allowing the land behind it to flood.
     • Overtime it becomes marshland creating new habitats. Flooding and erosion are reduced behind the marshland and it is fairly cheap.
     • People disagree on what land is allowed to flood (e.g. farmland would affect farmer's livelihood).