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Title: Report on the management of the drainage regime within Exminster Marshes
Author: National Rivers Authority South Western Region
Document Type: Monograph
In response to concerns that Exminster marshes are drying out and to evaluate the current management a study was made of the sites hydrology and ecological status. Field surveys were undertaken in the late summer of 1992, a period of low flows, with observations on flooding extending to May 1993. Inputs and outputs to the marshes were determined together with the flow regime within ditches. The temporary Alphin/Matford Brook intake was seen to be the major input to the system during low flow conditions. Ditches in which flow was unsatisfactory were identified and the number of dry ditches found to have increased since 1988. A simplified level survey was produced identifying areas of low ground likely to flood. Investigations on flooding within the catchment found that there is adequate storage capacity within the Exminster Marshes to provide protection to Alphington during conditions experienced in the 1960 flood. Flooding of the marshes had an expected theoretical return period of more than once each year. Surface flow across the marshes followed moderate falls of rain where the catchment was already saturated. These conditions were more common during the winter but could be expected at any season. Using a 1988 NCC full botanical survey of the sites ditch system as a base line along with records of past management the effectiveness of management practices in maintaining ditch diversity was investigated. De-weeding was generally found to maintain ditch diversity. A study of the distributions of certain rare plants at the site was made. Several species recorded in 1988 were not subsequently found in 1992, however results were not conclusive.
Publisher: National Rivers Authority
Publication Date: 1993
Publication Place: Exeter
Subject Keywords: MarshesField experimentationFloodingWater levelsSpecies distributionNature conservationDrainage
Geographic Keywords: Devon
Extent: 25; + appendices
Total file downloads: 30

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