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Title: East Devon public water supply strategy : the existence and potential use in yield analysis of historic flow records
Author: Liso Roach
Document Type: Monograph
In January 1993 South West Water Services Limited (SWWSL) applied to NRA SW for a licence to abstract water from the River Exe during the winter months to pump into Wimbleball Reservoir. In order to determine the licence, NRA SW made an assessment of the availability of resources for public water supply in the Wimbleball supply area. This involved the Water Resources Planning Team determining the drought reliable yield of the Wimbleball/Exe system. The drought reliable yield was defined as the maximum amount of water the system can supply throughout a 1 in 50 year drought. Typically the drought reliable yield varies according to a range of factors including the size of the reservoir, the pattern of the demand placed upon it, and most importantly, the nature of the inflow sequence. Recent work to identify the most appropriate methodology for accurately determining the yield of surface water resources such as Wimbleball Reservoir, indicates that ideally a daily flow record of about 100 years is required to represent the inflows into the reservoir (NRA, 1992). The record should be accurate, reliable and unaffected by artificial influences. The longest river flow record in the south west that can be obtained from the current network of gauging stations, initiated by the former River Boards, is 35 years. Both Thorverton gauging station, N.G.R. SS 936 016, and Preston gauging station, N.G.R. SX 856 746, on the 'Rivers Exe and Teign respectively have records of this length. However, neither of the records are sufficiently long to meet the requirements outlined above. This report details the research undertaken to locate, recover and catalogue the flow data and then assess its usefulness for yield analysis. The latter included an assessment of whether it could form primary data to represent reservoir inflows.
Publisher: National Rivers Authority
Publication Date: 1993
Publication Place: Exeter
Subject Keywords: Water supplyWater abstraction licensesWater industryWater reservoirsWater resourcesRiversForecastingData
Geographic Keywords: TeignExeEast Devon catchmentSouth Devon catchmentDevon
Extent: 23; + appendices
Total file downloads: 38

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