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The differing drainage basins in the UK.

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The differing drainage basins in the UK There are many natural factors influencing how a drainage basins main channel responds to rainfall, in this essay I hope write in detail the different natural factors, the opposition influencing these natural factors and the consequences on the volume of water flowing down the drainage basin to the main channel or river. Alongside stream channels are relatively flat areas of land known as floodplains, flood plains develop when streams and rivers overflow their levees spreading discharge and suspended sediments over the land surface during floods. Levees are ridges found along the sides of stream channels or rivers composed of sand or gravel. Levees are approximately one half to four times the diameter of the river (stream channel). Upon retreat of the floodwaters, stream and river velocities decrease causing the deposition of alluvium, repeated flood cycles over time can result in the deposition of many successive layers of alluvial material. Flood plain deposits can raise the elevation of the streambed. This process is called aggradation and can be disastrous to the whole drainage basin in the event of a flood as the depth of the river is reduced meaning the carrying capacity of the river is reduced too, so in the event of a storm and heavy rain the stream ...read more.


Parallel drainage patterns Parallel drainage patterns are ones where the water flows over areas with a steep relief or flows over non cohesive materials this is quite an effective basin except that there are not normally that many smaller tributaries leading to them they are all mostly larger stream channels Storm hydrographs Here we can see that the storm arrives then it takes some time for the water to pick up speed and velocity (lag time) this may be because when the water is in the tributary rivers it is not nessicarily flowing towards the stream channel it is flowing at right angles to it so in a storm with this type of basin the floods might affect the people living very close by as well as people further down stream. Also severe flooding might occur at the base of each tributary as it reaches the channel mouth as the water is coming down with such speed that it starts to erode at the points x and although rivers naturally meander it doesn�t naturally turn at right angles. With this drainage basin there aren�t that many sharp corners so the water is going to be able to flow quite easily to the stream channel but this is slowed down by the large pockets of water at certain stages down the stream channel. ...read more.


Also because of the surface the rock is on the decreasing side for discharge will be quite steep too because the water can travel quite quickly out of the basin too. But this creates another problem that is flash floods because the water rises so much so quickly. I.e. the water will rise and fall quickly but will breech the bankful discharge, the peak discharge will be higher in a basin like this, than one like a dentritic basin in bad weather because the water all arrives all at once instead of being spread out over a few days Storm hydrographs (parallel basins) These respond very quickly to storms and persistent rain as the water is transported straight to the stream channel flowing the same direction as it the lagtime is very short for this but flooding isnt experienced here unless there is a parallel basin further up stream as all the water is transported out of the way immediately. But by analyzing these I am only half way to answering the essay title because there is much more fluvial language that I have yet to use. There are many other natural factors which influences the mains channel and its response to rain fall. ...read more.

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