The impact of reservoir regulation on the processes of erosion and sedimentation of the delta in Lake Oyeren, Norway

摘要

The 9 km~2 delta in the Lake Oyeren reservoir has been affected by water level regulation since 1862. This paper reports the results of investigations carried out to identify the factors controlling the processes of delta erosion and sedimentation and to evaluate the impact of recent changes in the operational directives for power stations. Successive regulation phases have gradually reduced the amplitude of seasonal variations in water stage from the natural range of 8 m and resulted in an extended period of high and more constant water level. Local sediment redistribution within the delta has decreased over the years reducing the downstream extent of the sedimentation zone. As a result, a new phase in the delta development was initiated with marked proximal accumulation. The sub-aerial part of the delta increased rapidly in area as a greater proportion of the suspended load tended to be deposited on the delta plain. The impact of the delta changes on fish communities and fish habitats is discussed.