(Power Stream, Vol. 4, No. 10, December 2007, pp. 38-40)
In India over 4000 large dams built with a storage capacity of about 213 (BCM). About 6000 million tonne (MT) of soil is eroded every year as a result of sheet erosion. Besides gully and ravine erosion ravages 8000 ha of useful land annually. CWC after analyzing data of 144 reservoris (cumulative gross capacity of 94.8 BCM) found that average annual percentage loss of gross storage capacity is 0.44 per cent and that of live storage is 0.3 per cent. Based on another study done by CWC weight of total sediment deposits is of order of 1100 MT annually. The sedimentation rate of reservoir was found to be varying due to factors like hydrometeorology, physiography, climate etc. The actual rate of sedimentation is for more than design rate of sedimentation in most of the projects.
