Errors in measuring the flow discharge in a trapezoidal open canal

摘要

The relative error arising in measurement of flow discharge by a level gauge in a gravity (open) canal is studied analytically. It is noted that resulting error is a combination of two types: fundamental (basic) and complementary. The sources of these errors arc clarified. On the basis of Manning's uniform flow formula, the governing relations for both types of errors are derived and analyzed. The comparative effect of each error component on discharge measurement accuracy is estimated.