To what extent the flood alleviation scheme has had on the environment and people of Swanage and to find out weather the scheme has been successful.

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Introduction

For my GCSE Geography coursework I have been asked to go to Swanage based in the South East of England, Dorset, and find out to what extent the flood alleviation scheme has had on the environment and people of Swanage and to find out weather the scheme has been successful.

        I will also be investigating how Swanage has been previously affected in the past by flooding, using photographs, newspaper clipping and a video.  Next I will use geology maps, OS maps, base maps with basin and drainage maps of Swanage along with classroom notes on factors effecting flooding to answer how Swanage has been affected by floods in the past and what caused them.  Then I will investigate what has been done to control the flooding using base maps showing locations of the various element of the SFAS, field work, and river cross sections at the natural and improve channels and finally notes from the visit to SFAS site.  Lastly I will show what the effect of the SFAS has been on both the beach; environment and people using fields work on ‘beach profile’, ‘level of beach on each side of groynes’ and lastly class work notes.

         Swanage is a small town tourist area, with most of its land being used as woodland, farmland, small residential area, or as tourist resorts and attractions.  The tourism attractions in the Swanage include caravan sites, camping sites, parking, information centres, museums, a pier, field study centres, natural trust areas and nature trails.  Even though Swanage is a tourist area it is not a commuter town and is very isolated with only one railway and a limited number of road.  The nearest main town is Bournemouth which is 45 minuets away and includes a ferry journey.  The residential area is small and calm making it ideal for older people and those with small children as the area has two schools.

        The headlands of Swanage are quite obvious and easy to notice.  Both the chalk and Purbeck bed are hard rock which is found to the north and south of Swanage.  The soft rock has been severely eroded in comparison to the other rock, especially the chalk found at Studland Bay.  This is where the famous ‘Old Harry’ stands.  This site receives a lot of tourism and still has been eroded less than the Swanage area.

Question 2

        In any place there is obvious causes of flooding, the most common cause of flooding is heavy rainfall over a long periods of time, often lasting many days, thunderstorms being the most severe of these.  If heavy rain fall occurs eventually infiltration will be replaced by surface run off.  In Britain, the summer is the most common time for flooding, as after long dry spells occur the ground becomes impermeable and the water can not infiltrate through the ground surface.  The surface run off then causes the river levels to rise and flash flooding happens.  Snow over a long time period is also a cause for distress as water is held in storage for several days until the temperature increase and all of the water that was being held is released.  This risk is increased if it rains after snowing as the ground is still frozen and impermeable.

        Sandstone and limestone are rocks that are permeable. Granite is an impermeable rock type.  As with rocks you also have permeable and impermeable soil, for example, sandy soils are permeable whereas clay soils with not let water infiltrate it. Flood risks are much higher in areas with impermeable surface run off and river basins.

        Vegetation intercepts rain fall and reduce the amount as well as the time the rain takes to reach the river.  Therefore river basins with vegetation have a lower risk of flooding.  

        Human activity means that there is a lot more surface run off, due to the impermeable concrete and tarmac ground laid when urban areas are built up.  This means that infiltration is reduced while surface run off is increased.  Deforestation is also common in urban areas, so not only is there a greater surface run off but there is also no interception.  Gutters and drains are made to deal with this problem, however they may get the rain down to the river more quickly but sometimes there is simply too much water and the underground pipes are not big enough to cope with the amount of water, this causes flash flooding.

        Swanage town is in the middle of a valley with highland to the North which is between 199 and 117 meters above sea level, to the South up to 125 meters above sea level.  Swanage however is less than 20 meters above sea level.  The sharp gradient on each side of Swanage means that the surface run off is on a steep slope, so precipitation makes its way very quickly towards the town centre which is a natural flood plain.  Surface run off is increased by the pull of gravity.  Swanage has been built upon a flood plain and on top of the Swanbrook River.  The mouth of the river is also very small meaning that there is a struggle to water into the sea, which is contributed to be the concrete and tarmac ground which makes infiltration impossible and increases the speed of the surface runoff.  The seas tides add to the problem as during high tides the waves run into the river.

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        To the North if Swanage lays Clayton which is impermeable and has a great surface run off. There is also little interception, as most of the vegetation lies outside of the river basin.    

        Swanage town is now a built up area so there is an even greater risk of flooding because of the impermeable ground.  The grounds surrounding Swanage are Weldon clay and Purbeck beds, increasing the surface runoff even more greatly.  There is also little vegetation decreasing the amount of interception making Swanage prone to floods.

Question 3

         The purpose of the experiment was to analyse the ...

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