The Impact of Building Harlow New Town on Canon's Brook

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The Impact of Building Harlow New Town on Canon's Brook There are likely to be many effects of building a town on a brook. We can see that the most probable responses would be that more water flows into the river and the flood risk increases. However, there are likely to be many other contributing factors and other responses to these rainfall events. In this essay, I am going to examine how the changes to the response of the river occur and what these changes actually are. The river responded to rainfall very differently in three different time periods. In 1950, the peak discharge was about 1.8 cumecs. In 1950, the lag time would have been much longer due to the fact that there were no drainage systems. Water flows into the drains, and is taken straight to the nearest river which would greatly decrease the lag time. As the drainage system developed, the lag time would decrease, and this is shown as in later years the lag time is much lower. The flood risk for the area in 1950 is quite low because there is not a lot of water being discharged from the river. In 1950, the rising limb and falling limb are gentle. In the second time period, 1958-62, the peak discharge is 5.2 cumecs. We can see that the discharge has increased from the discharge of 8 years ago. The lag time is also much shorter in this time period, which is a definite contrast to the previous one. The rising and falling limbs are also different to the previous time period. The main difference is that the rising and falling limbs are much steeper. The flood risk is quite high in this time period as the discharge is quite high. Also, the two limbs come to more of a point, rather than the curve that was present in 1950-54. In the third time period, 1966-68, the peak discharge was 8 cumecs. This is a huge increase from the previous two periods. The lag time is has decreased from before, which is also a contrast from the previous

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