Reversal of eutrophication in four Swiss lakes: evidence from oligochaete communities

One purpose of river maintenance within Britain is to deliver given standards of land drainage service relating to the control, within acceptable limits, of flooding and waterlogging on riparian, mainly agricultural land. Aquatic weed removal is a major maintenance activity. Authorities responsible for cost-effective river maintenance need to determine the extent and timing of vegetation removal in channels of various types. The impact of maintenance is being studied on 12 sites in five regions of the National Rivers Authority (NRA) in England and Wales. The impact of differing maintenance regimes on flooding and waterlogging and the consequences for agricultural performance are assessed. The longevity of maintenance in terms of the time taken for the without maintenance watercourse condition to be reinstated following maintenance has been determined for gravel, sand and silt bed rivers on which vegetation cutting has been performed. The estimated benefits of river maintenance are set against costs to help formulate best maintenance strategies and prioritise and justify maintenance works.