Anne Milot
Enviromental Geography
Topic: Coastal Problems
Common types of coastal problems are: pollution, erosion, salt intrusion, flooding calamities, habitat degradation / loss of biodiversity.
Coastal erosion of rocky cliffs and sandy beaches results from the action of ocean waves and currents. This is especially severe during storms. In many parts of the world the loss of land due to coastal erosion represents a serious problem. The action of waves, however, does not extend to a great depth, and the sea tends to cut a flat platform, characteristic of marine erosion, into coastal rocks.
Various measures can be taken to reduce the risk of flooding, especially in the settled parts of floodplains. One of the most effective methods of reducing damage has been to alter the size of floods themselves. By planting trees, controlling soil erosion, and preserving wetlands, people have helped to reduce the size of floods. Special channels have been constructed to divert floodwaters away from built-up areas. The construction of dams has also been a very successful means of controlling floods.
Constructing dams, however, can also alter the processes that shape the floodplains farther downstream. Since most sediment carried by a river settles out in the reservoir behind a dam, the water flowing past a dam has very little sediment in it. Water poor in sediment will scour sediment from the floodplain immediately downstream from the dam, resulting in erosion. By trapping nutrient-rich sediment and preventing annual floods, large dams halt the natural reinvigoration of the fertile floodplain soils that usually accompanies annual flooding. Without large floods, some river channels fill with debris or become narrow with overgrown vegetation, changes that might adversely affect native fish and birds.
Enviromental Geography
Topic: Coastal Problems
Common types of coastal problems are: pollution, erosion, salt intrusion, flooding calamities, habitat degradation / loss of biodiversity.
Coastal erosion of rocky cliffs and sandy beaches results from the action of ocean waves and currents. This is especially severe during storms. In many parts of the world the loss of land due to coastal erosion represents a serious problem. The action of waves, however, does not extend to a great depth, and the sea tends to cut a flat platform, characteristic of marine erosion, into coastal rocks.
Various measures can be taken to reduce the risk of flooding, especially in the settled parts of floodplains. One of the most effective methods of reducing damage has been to alter the size of floods themselves. By planting trees, controlling soil erosion, and preserving wetlands, people have helped to reduce the size of floods. Special channels have been constructed to divert floodwaters away from built-up areas. The construction of dams has also been a very successful means of controlling floods.
Constructing dams, however, can also alter the processes that shape the floodplains farther downstream. Since most sediment carried by a river settles out in the reservoir behind a dam, the water flowing past a dam has very little sediment in it. Water poor in sediment will scour sediment from the floodplain immediately downstream from the dam, resulting in erosion. By trapping nutrient-rich sediment and preventing annual floods, large dams halt the natural reinvigoration of the fertile floodplain soils that usually accompanies annual flooding. Without large floods, some river channels fill with debris or become narrow with overgrown vegetation, changes that might adversely affect native fish and birds.