DETERMINATION OF UNIT HYDROGRAPHS BY MULTIPLE STORM ANALYSIS

This paper discusses the derivation of a unit hydrograph by multiple s torm analysis using least squares methods. Variations of least squares method was generalized using the framework of weighted ridge analysis . The paper also shows two theorems to support using multi-storm analy sis to derive UH. In addition, an issue was addressed on the scaling e ffect in the conventional multi-storm analysis which could create pote ntial bias toward large storms in deriving a multi-storm UH. For that, a simple scaling procedure was proposed to reduce such potential bias problem. Numerical investigations were conducted to examine the perfo rmance of the scaling procedure by comparing with the conventional mul ti-storm analysis (without scaling) and the HEC-1 weighing procedures. Based on various performance criteria using a total of 39 storms from three watersheds, the proposed scaling procedure was found to produce a quite desirable UH.