Irrigation in the Pacific Northwest

Rectangular Submerged Orifices

This calculator determines the flow rate of water through a rectangular submerged orifice. A submerged orifice is an underwater hole that water goes through. In this case the hole has a rectangular shape. The water level on the upstream side is higher than the water level on the downstream side. This height difference also called the height change. The area is based off the measurements of the rectangular orifice.

Learn more about the units used on this page.


Height Change:
Flow Rate:



The Equations

The equation to determine the flow rate for a Rectangular Submerged Orifice is:


= Flow Rate in cfs.

= Area of the Rectangular Orifice in square feet.





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