Flooding
Increased Risk of Flooding
Building a New Town at Adlington presents clear and material flood risks. Large parts of the site lie in Flood zones 2 and 3 1 (areas with medium-to-high probability of river flooding), meaning the baseline risk of flooding is already elevated. Natural Flood Defences The removal of large areas of trees and vegetation and the replacement of permeable ground with roofs, roads and concrete, will significantly increase surface water runoff. Tree roots, soil and fields act as natural sponges and serve as a Natural Flood Management system 2. Mature woodland and soils slow, store and evaporate rainfall; removing thousands of trees reduces that storage capacity and accelerates the speed and peak of runoff into ordinary watercourses and rivers, raising flood peaks downstream. The cumulative effect of hard surfacing across a very large new neighbourhood would therefore tend to increase local and downstream flood frequencies. Large deciduous trees can absorb and evaporate up to 2000 litres of water per day 3.
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Building a New Town at Adlington presents clear and material flood risks. Large parts of the site lie in Flood zones 2 and 3 1 (areas with medium-to-high probability of river flooding), meaning the baseline risk of flooding is already elevated. Natural Flood Defences The removal of large areas of trees and vegetation and the replacement of permeable ground with roofs, roads and concrete, will significantly increase surface water runoff. Tree roots, soil and fields act as natural sponges and serve as a Natural Flood Management system 2. Mature woodland and soils slow, store and evaporate rainfall; removing thousands of trees reduces that storage capacity and accelerates the speed and peak of runoff into ordinary watercourses and rivers, raising flood peaks downstream. The cumulative effect of hard surfacing across a very large new neighbourhood would therefore tend to increase local and downstream flood frequencies. Large deciduous trees can absorb and evaporate up to 2000 litres of water per day 3.
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