The Two Sides of Sediment: Necessity and Problem
Sediment belongs to the river. It protects the river from being cut into its bed by the force of the water. Installing a reservoir changes the natural balance of the river profoundly. The reservoir now keeps most of the sediment, and only a small fraction is sent down the river. Rivers with a sediment deficit tend to develop a “Grand Canyon Phenomenon”. The downstream river is furthermore affected by erosion. Until now there have been some conventional attempts to try to cope with sedimentation in reservoirs.
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All of them – reservoir flushing, manual dredging and wet dredging with optional pumping downstream – only partly solve your problems and often create new ones. Most approaches are extremely expensive and/or cause a significant reservoir/plant shutdown with tremendous economic losses. Both sediment extraction and massive flushing create severe ecological damage.