Printed from: https://conservationhandbooks.com/waterways-wetlands/dams-weirs-and-sluices/weirs/
Weirs are barriers, usually in flowing water, which hold back water and are overtopped by it in normal conditions. They may be part of the overflow systems of dams or they may be placed on their own where only a small head of water is to be ponded back, for example to create fish pools....