Reservoir yield assessment in a changing Scottish environment

The application of a variety of reservoir yield estimation methods is described against the background of a review of yield in Scotland. The study is timely, both in the context of the possible effects of climate change, the institutional re-organisation of the water industry world-wide--but originating largely from the UK-and the emerging issues of sustainability and the shift from supply to demand side management. To set the paper in context, the study was undertaken just prior to the transfer of responsibility for water supply from regional councils to new water authorities in 1996, and following the quinquennial Scottish Office Environment Department's survey of water resources in 1994. A comparative review of assessment methods was undertaken in order to recommend a flexible and consistent approach for single sources, but with a view to extending this to conjunctive schemes. A case study of Loch Bradan showed that the derivation of the inflow record and definition of the catchment boundary are at least as important as the yield assessment method itself.