• The water stored in the reservoir is generally free from silt.
  • The flood inflow is generally muddy and heavily charged with silt.
  • Thus during floods there are two waters having different densities present is the reservoir.
  • Heavily silt charged water flows along the bottom of the channel towards the dam under the influence of gravity.
  • This current of heavily silt charged water flowing along the bottom of the reservoir towards the dam is know Density current.
  • If the density currents, are directly discharg out of the reservoir by suitably positioning and operating the sluice gates, the rate of reservoir silting can be considerably reduced.