DISCOVER
×

How to calculate discharge of a river

Updated March 23, 2017

In order to calculate the discharge of a river, you need a cross-sectional area of part of the river and you need the velocity of the river. To find the cross-section area of the river, you can simplify the equation by assuming the cross-section is a rectangle. This helps give a general estimate since finding the true area is complicated because the water is flowing and you cannot get an accurate description of the shape. Use the formula q=va to calculate the discharge of a river, where "q" is the discharge, "v" is the velocity and "a" is the cross-sectional area of the river.

Measure the depth and the width of the river. For example, assume a river is 4 metres deep and 5 metres wide in one area.

Multiply the depth by the width to find the cross-sectional area. In the example, 4 metres x 5 metres equals 20 metres^2, or 20 metres squared.

Find the velocity of the river. In the example, assume the velocity 3 metres per second.

Multiply the cross-sectional area by the velocity to find the river discharge. In the example (20 metres^2) x (3 metres/second) equals 60 metres^3/second. The calculated discharge of the river is 60 cubic metres per second.

Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Carter McBride started writing in 2007 with CMBA's IP section. He has written for Bureau of National Affairs, Inc and various websites. He received a CALI Award for The Actual Impact of MasterCard's Initial Public Offering in 2008. McBride is an attorney with a Juris Doctor from Case Western Reserve University and a Master of Science in accounting from the University of Connecticut.