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Submerged weir formula

Submerged weir diagram

Excerpt from: Rajaratnam, N., Muralidhar, D., 1969. Flow below deeply submerged rectangular weirs. Journal of Hydraulic Research 7, 355–374.

In submerged flow, the flow rate depends on the upstream water level hamont and the downstream water level haval (Rajaratnam et al., 1969):

Q=Cd2gLhavalhamonthaval

With:

  • L the weir width in m
  • hamont the upstream head on the weir in m
  • haval the downstream head on the weir in m
  • Cd the discharge coefficient (equal to 0.9 by default).

This formula is not recommended for flooding below 80%.

Rajaratnam, N., Muralidhar, D., 1969. Flow below deeply submerged rectangular weirs. Journal of Hydraulic Research 7, 355–374.