The discharge of streams and canals has to be measured for following reasons.

  • The irrigation potential of a particular river at a particular point can be estimated only if discharge characteristics of the river at that particular point of the stream are known.
  • If flow in the stream falls too low during particular season, it may become essential to construct dam or weir.
  • Even height of the dam or weir depends upon the discharge of the river.
  • Storage of water is further dependent upon the available discharge which again necessitates measurement of discharge.
  • Because water in the canal is left proportional to the area it has to irrigate, measurement of discharge again becomes necessary at all works.
  • Regulation of canal system is almost fully based on the discharge measurement, as water in each canal has to be left equal to the capacity of the canal.
  • To conduct research work as regards to the behaviour of streams and canals, discharge in them has to be measured.
  • River discharge is also required to be known in the design of the river training works.
  • Discharge may have to be measured, when water of a particular river has to be distributed amongst different countries.
  • A canal supplying water to more than one state has to be measured and distributed.