To what extent do you agree with the view that coastal systems are too complex to ever be completely manageable?
Louise Carvey
To what extent do you agree with the view that coastal systems are too complex to ever be completely manageable?
Of all the earth’s natural environments, the coast is the most rapidly changing and dynamic. It can be defined in several ways, but at its simplest, it is the place where land and sea meet and interact. The coast is under numerous pressures due to its pull for economic activity, settlement, recreation and wildlife. Its form is greatly influenced by Terrestrial (Weathering, erosion, deposition, rock type/structure). Human (Pollution, recreation, settlement, defenses) and Atmospheric (Climate. Marine, Waves, tides, salt spray). They all interact to produce the enormous variety of coastlines found worldwide. (From beaches and cliffs to coral reefs).
As things like coastal tourism have become more frequent, humans have found it increasingly necessary to attempt to control the effects of the sea. The main reasons for coastal management are to protect the coast from the erosive effects of the sea and to increase the amount of sand on the beach. Many strategies have been tried around the world, and these can be divided into two main groups, hard and soft engineering. Hard engineering methods aim to stop the coastal processes from occurring. Soft engineering methods try to work with nature to protect the coast.
Coastal lands and sediments are constantly in motion. Breaking waves move sand along the coast, eroding sand in one area and depositing it on an adjacent beach. Tidal cycles bring sand onto the beach and carry it back into the surf. Rivers carry sediment to the coast and build deltas into the open water. Storms cause deep erosion in one area and leave thick over wash deposits in another. Plants retain sediment in wetlands and impede movement of coastal dunes. Natural processes that change the water level also affect coastal dynamics. Taken individually, each natural process of coastal transport is complex; taken collectively, they create an extraordinarily intricate system that attempts to achieve a dynamic balance.
The complexity of this system means that individual factors make a big influence on the entire coastal system. Long shore drift is responsible for most of the interactions within the system through transfers of sediment. Loose materials are relocated from sections of the coastline dominated by erosion to those where deposition occurs to form constructive landforms such as beaches, spits and bars. Winds can carry sand inland as an output from the coastal system. Sea-level change occurs over a range of timescales. Short-term change occurs as a result of wave and tidal action. Tides are changes in water level due to the gravitational attraction exerted on the oceans mainly by the moon, and to a lesser extent by the sun. British coastlines experience semi-diurnal tides where there are two low and two high tides each day. Tidal range is the vertical distance between low and high tide and controls the vertical distance over which waves and tides can carry out geomorphic work. The tidal range around the British coastline is variable, over 6m in Morecambe Bay and only 1.8m in Christchurch Bay. In the intertidal zone between high and low tides the rocks and sediment are exposed for a few hours each day, when sub aerial weathering and biological processes operate. This erosion and weathering but sub aerial processes provide direct sediment inputs which then contribute into forming depositional landforms such as spits. Spurn head is an example of an unstable spit. The long shore drift from north to south carries a particularly heavy load because of the rapid rates of erosion. The dominant wind direction is from the north east. The spit’s growth has created still waters behind it, in which finer sediments have been deposited; at the same time the deep water channel in the estuary is being pushed southwards. Tidal and wave movements cause short term changes in sea level, but it is long term change that is important for coastal landforms and management. There are two causes of long term sea level changes, both of which have global as well as British significance. Eustatic changes are changes in the size of the ocean store (a worldwide change in sea level) caused by climatic change resulting in the growth or decay of ice caps. Already since 1990, sea levels have risen 10 -15cm. this has serious implications for low lying coastlines and for flooding and erosion rates along all coastlines. In regions where climatic change results in increased storm magnitude and frequency, the higher wave energy will result in adjustment throughout the coastal system. Any management strategies that are undertaken will be almost be impossible to cost benefit analyses because the climate is unpredictable, it is impossible to determine how beneficial the strategies would be to the coastal system.
