A Least‐Squares Hydrograph Analysis of Complex Storms on Small Agricultural Watersheds

The feasibility of a least‐squares technique developed by Snyder [1955] for extracting unit hydrographs from complex storms was investigated for application to small agricultural watersheds. The procedure is the reverse of hydrograph synthesis. Rather than summing unit hydrographs to synthesize a complex storm, the unit hydrograph was calculated. When summed, the unit hydrograph produced the best fit to the storm hydrograph. The feasibility of the technique was clearly shown on four of the five ARS watersheds in the study. Large perturbations occurred in the calculated unit hydrographs on one of the watersheds, but sensible results were obtained on the remaining four. The calculated unit hydrographs varied from storm to storm as expected. The results of these analyses demonstrate the feasibility of the least‐squares technique as a means of analyzing all storm hydrographs on small agricultural watersheds to detect the nonlinearity of the rainfall‐runoff process.