Brink depth technique to measure free overfall in field channels

Abstract

The easy and accurate measurement of irrigation water through field distributaries permits its economic use. Less number of measurement of flow parameters in channels will minimize the error in discharge calculation. A laboratory procedure was carried out to develop the measurement technique of flow in irrigation channels. The relationship amongst the brink depth, ye' the critical depth, y C' and unit discharge, q, is developed as q=cyek, where c, k are constants. In present investigation, the relations are yc=1.37 Ye and q=5.08 ye3/2. Similarly a relationship among, yeyo, ycyo and q, where yo is the normal depth was found as yc/yo=1.33 yeyo and q=4.80e3/2 . The results are tested in field distributaries and the technique was found suitable in different field conditions. There is little impact of infiltration characteristics on discharge evaluation.