Erosion in regulated reservoirs

Due to extensive regulation for hydro power, serious erosion along the shores at some reservoirs has been observed. The degradation of the tributaries was particuarly dramatic. A programme to monitor the development of the erosion of three reservoirs was established. The programme consists of: - Aearial photography - Regular photo recording of interesting spots - Measurement of suspended material in the reservoirs. The programme was more intensive the first years after 1973, but is still being followed up at intervals of years. Among the findings so far is The rate of degradation and eroded areas at the outlets of the tributaries is related to - drainage area - soil composition - time. The development of new quasistable shores is dependent on - wave activity - soil composition - ice conditions - time. The sediment concentration varies regularly with seasonal and hydrological conditions such as - waterlevels - wave activity - ice conditions - waterdis-charge in tributaries. For some of these relations it has been possible to formulate general expressions. Findings under (a) will be reported in this paper.