Desilting Basin Design Concept 3f303n

Question 5 Should desilting basins be provided at all? Answer 5

In storage schemes with high dam and very large reservoir, the requirement of desilting basins are not there at all. In run off the river scheme with reasonable reservoir size, where the water gets enough time to shed off its suspended particles before entering into the water conductor system, again the requirement of desilting basins can be dispensed with. In run off schemes with small reservoir the necessity of desilting basins are normally felt. Again in the type of hydropower development, if the design discharge is enormous to be accommodate in a reasonable size of desilting chambers constructed economically in the given geological set up the needs to be economically weighted viz-a-viz to the turbines and outages for the maintenance of the machines. If the longitudinal slope of the river is very mild, the outlet for the silt flushing tunnel, which takes off from the bottom of the desilting chambers, will have to be placed quite far from the intake in order to achieve the reasonable safe level against atleast annual flood, resulting in very long silt flushing tunnel and make the entire system less efficient