• The falls may be divided into following two types:

1. Meter falls

2. Non-meter falls.

1. Meter Falls.

  • The falls which can be used to measure the discharge flowing over them, are known as meter falls.
  • Such falls must have broad crest so that the discharge coefficient remains constant under variable head.
  • Glacis type falls are most suitable as meter falls.
  • If section of the channel at the site of the fall has to be flumed.
  • From economic considerations, smooth U/S transition.
  • Should be provided to avoid turbulences and also to maintain accurate stage-discharge relationship.
Sloping meter fall
Sloping meter fall

2. Non-meter Falls.

  • The falls which cannot be use to measure the discharge passing through them, are known as non-meter falls.
  • Vertical drop falls cannot be used as meter falls.
  • Some vacuum is developed under the nappe of falling water, which causes non-uniform flow conditions.