Reservoir bathymetry, capacity and sedimentation rates

Co-Investigator: Dr Daniel Parsons, Dr Jeff Peakall, Prof J Best

Sedimentation in reservoirs is a potential problem for water supply companies, such as "Yorkshire Water". The Business currently has a limited knowledge, however, of the extent of sedimentation in its reservoirs and is, therefore, seeking to improve its understanding. Over time, sedimentation can reduce reservoir capacity and thus the overall water yields for the full range of reservoir levels. The sedimentation rates and the spatial distribution of settled materials within the reservoir also have implications for reservoir scouring frequency and thus the water quality supplied. Moreover, knowledge of the extent of sedimentation in the reservoir and improved understanding of sediment releases during scouring will help YW to understand how it may impact upon the receiving water and help the business to comply with the demands of the Water Framework Directive.

This project will use new surveying techniques, namely multi-beam echo sonar (MBES), to obtain the full bathymetric details for a test reservoir, Gouthwaite, in North Yorkshire. The results obtained through this work will provide well-constrained estimates on water capacity and yields for the full range of reservoir stage levels and will indicate loss of yield due to sedimentation since previous surveys were performed, by Huddersfield Polytechnic in the 1980's and Jeremy Benn Associates in 2003. The data obtained will also supply information on the distribution of sedimentation across the reservoir and will aid determination of longer-term sedimentation rates throughout the reservoir, providing baseline timescales for scouring procedures and frequencies required. As well as determining the extent and pattern of sediment deposition in Gouthwaite reservoir, the current project will highlight the potential for MBES to be used on a regular basis for monitoring of sedimentation in Yorkshire Water's reservoirs.