Study on Flow Measurement Based on the Theory of Weir Flow in Rectangular Channel with Free Overfall

Based on the analysis on principle of weir flow,the theoretical formula for the flow measurement in rectangular channel with free overfall was proposed.The coefficient of discharge correction was determined by channel slope and channel roughness.A serial of experiments about flume were carried out with9 kinds of channel roughness and 2kinds of channel slope.The results showed that the flow through the weir was smooth,the discharge formula was concise and practical,and the relationship between flow coefficient m and was linear,the computational results correspond closely with the experimental results.