U.S. Department of the Interior


Date of this Version



Published in Hydraulic Engineering: Saving a Threatened Resource—In Search of Solutions: Proceedings of the Hydraulic Engineering sessions at Water Forum ’92. Baltimore, Maryland, August 2–6, 1992. Published by American Society of Civil Engineers.


Groins are defined as an elongated obstruction with one end on the bank of a stream and the other end projecting into the flow. Groins may be permeable allowing water to flow through at reduced velocities or impermeable blocking the current. Groins have been used successfully for river bank protection since the 19th century. Extensive research was conducted to determine the most recent design criteria for groins.

The criteria necessary to design a groin field are:
1. groin orientation;
2. length and spacing of groins;
3. predicting scour at groins;
4. elevation of groin crest;
5. groin side slopes and roots;
6. location of groins within river reach;
7. riprap size; and
8. flow conditions around groins.