Silt Clearance Problems
The KBD is proposed to have an orifice spillway, 40-ft below the minimum water level of the reservoir. And is believed to work as the ultimate remedy for all the sedimentation problems.
A significant relation of sediment sluicing has been found with the occurrence of piping action under the foundations of the dam.
Its has been reported by K.R Sharma in his book; Irrigation Engineering (2nd edition, India Printers, Jullundar, 1949) that, the Aswan Dam on Nile, constructed on the strongest footings of granite stone, has been found to suffer from foundation damages with each sluicing operation (which discharge the silt at a mean 20 ft/sec velocity). And correspondingly, the sluicing operation consumes a major portion of the operation and maintenance budget of the dam.
Given the 40-ft lower orifice spillway to exclude the sediment of the reservoir, and the geological formations (discussed earlier), it is feared that the recurring sluicing operations would result into piping actions under the dam footing, thereby putting the stability of structure at stake.