An efficient method of discharge estimation based on probability concept

The probability law describing the velocity distribution at a channel section in rivers and streams is resilient and invariant with time and discharge. This is based on the observation that its parameter, the average ratio of the mean and maximum velocities, is invariant with time, discharge, and water level. This in turn can serve as the basis for an efficient method of discharge measurements in rivers and streams. The method is applicable in both steady and unsteady flows in rivers, and can be used with any velocity-measuring equipment to drastically reduce the time and cost of discharge measurements. Its most important utility, however, is its applicability in unsteady, high flows to collect data that are essential in critical situations such as flow forecasting but cannot be measured by conventional methods. The various steps as well as the reliability of the method are illustrated.