Weir 2
Weir 2 : (a) A low dam built across a stream to raise the upstream water level (fixed-crest weir when uncontrolled); (b) A structure built across a stream or channel for the purpose of measuring flow (measuring or gaging weir); (c) A structure built into a levee or river bank that allows water to flow from the main river channel into a bypass channel during time of high flows