Water Cycle Study - East Devon District Council

Exeter and East Devon Water Cycle Study
3 The water cycle catchment
3.1 Introduction
3.1.1 Figure 3.1 shows the natural and engineered elements that comprise the Water Cycle in the
context of this study. Although the methods of dealing with the water cycle elements may change,
the basic requirements never will. Rain will fall, clean water will be needed for life and sewage
treatment will be needed for public health.
Figure 3.1 – The water cycle
3.1.2 Human manipulation of the natural water cycle can result in negative impacts on the water-related
environment, which can indirectly affect the ecology that is dependant on the natural features of a
water cycle. These features are potentially at risk from future development due to the associated
increase in demand for clean water supply taken from natural sources; increased treatment of
waste water that has to return to receiving waters; and the alteration of natural surface water flow
paths.
3.1.3 There are two key uncertainties in the study of any water cycle: Climate change, which can be
modelled crudely for some aspects of the water cycle, and the Water Framework Directive
((WFD) already transposed into UK law) which could mean that water quality standards improve
significantly between now and 2016. What is acceptable now may not necessarily be so in the
future.
3.2 River catchments and hydrology
3.2.1 The river catchments within the study area are shown in Figure 3.2 The main watercourses that
drain the core study area are the River Exe and its tributary the River Clyst. Just upstream of the
growth point area, the River Exe is joined by two major tributaries, the River Creedy from the
west and the River Culm from the east. The wide floodplains of the River Exe and River Culm
provide significant floodwater storage immediately upstream (north) of the core study area,
attenuating and reducing peak flows. Downstream of Exeter, the River Exe flows in a southeasterly
direction into the Exe estuary.
3.2.2 Elsewhere in East Devon, the other main river catchments are the River Otter in the west of the
district (flowing through Newton Poppleford and to the coast at Budleigh Salterton), the River Sid
19 Ref EWCS April 2010