Abstract
The unit hydrograph principle was first presented in 1932 by LeRoy K. Sherman,2 M. Am. Soc. C. E. Since then it has been developed into a usable method for surface run-off analysis. The most notable advance was the introduction of the distribution graph and pluviagraph in 1934 by Merrill M. Bernard,3 M. Am. Soc. C. E.