Gaugenotch

Gauge-notch in hydraulics is an arrangement for measuring the quantity of water flowing past any section of a small stream. It is a V-shaped or rectangular notch cut out of a board which is fixed across the channel in such a way that the water has to flow through the notch. It must have sharp edges to give accurate results, which are calculated from the dimensions of the notch and the head of water behind it.

The word gauging is employed to denote the measurement of the capacity of casks.