An IUH Equation Based on Entropy Theory
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The instantaneous unit hydrograph (IUH) is a commonly used method for computing surface runoff hydrographs from small watersheds. Assuming travel time as a random variable, a general equation for IUH is derived using the entropy theory. This equation specializes into several well‐known equations, such as the gamma distribution, Lienhard distribution, and Nakagami‐m distribution, to name but a few. The general equation has three parameters, two of which are based on specified information (or constraints) on travel time, and the third parameter is an exponent that can also be determined from the specified values of travel time. In this study, the derived equation is tested on two small agricultural experimental watersheds. Surface runoff hydrographs computed using the derived IUH equation are found to be in satisfactory agreement with observed surface runoff hydrographs.
Instantaneous unit hydrograph
Principle of maximum entropy
DepartmentBiological and Agricultural Engineering (College of Agriculture and Life Sciences)
Singh, V. P. (2011). An IUH Equation Based on Entropy Theory. American Society of Agricultural and Biological Engineers. Available electronically from