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14th March 2022

Sediment continuity through run-of-river hydropower schemes


The Scottish Government’s ambition to decarbonise its electricity generation means that run-of-river hydroelectric power schemes are now a feature of many Scottish catchments. The essential requirements of these schemes (adequate hydraulic head and flow) mean that their locations often coincide with important freshwater habitat. A scheme can have various effects on the quality and extent of this habitat, in and downstream of the depleted reach (between the intake and tailrace), and upstream of the impoundment. The interruption of natural sediment movement is one such effect and, if measures to ensure that conveyance is maintained are not included in the design of a scheme, it can have significant and far reaching consequences for habitats, species, channel evolution, and adjacent land. It can also, significantly for the operator, affect the efficiency and profitability of a scheme. The realisation that the need to maintain sediment continuity has not been adequately taken into account for many schemes was the impetus for this project. The research published in this report has led to recommendations for dealing with accumulations of sediment at operational schemes, and for the incorporation of sediment management measures in proposed schemes. The effects of climate change and the biodiversity crisis have increased the imperative for remedial action and to ensure that measures for maintaining sediment movement and other natural processes are incorporated in the design of existing and new schemes.