In order to control silt entry into the canal, following two methods of regulation of a head regular may be adopted.

  1. Open flow regulation.
  2. Still pond regulation.

Open flow regulation.

  • In this method undersluices are kept open to pass the surplus river water D/S.
  • Bottom layers of silt laden water are lead to under sluices and passed to the D/S.
  • The top layers of water having comparatively less silt, are diverted to the canal.
  • In this operation the pocket behind the undersluices remains clear of silt.

Stilling pond Regulation.

  • In this case a separate pocket is formed in the river and head regulator is fixed in this pocket.
  • Only that much water is admitted in to the pocket as is required by the canal.
  • The excess water remains passing D/S over the weir proper.
  • In this case water, in the pocket is almost still. This pocket is also known as still pocket or still pond.
  • Since velocity of flow here is very small, the silt gets deposited in it.
  • When silt reaches the level of say about 1 m below the crest of the head regulator, the gates of regulator are dropped, and gates of undersluices opened to scour off the deposited silt D/L.