Adequacy of Nakagami-m Distribution Function to Derive GIUH

Abstract

Nash and Clark based geomorphological instanteneous unit hydrograph (GIUH) approach proved its usefulness to compute the synthetic unit hydrograph (SUH) and in turn the direct surface runoff component for ungauged catchments. In recent development, two-parameter Weibull’s distribution, coupled with Horton’s ratio, was used to derive the SUH. In continuation with these innovations, present study was conducted to test the adequacy of two-parameter Nakagami- m distribution to derive the GIUH along with two-parameter logistic, two-parameter Weibull, and two-parameter gamma distributions (Nash model). Nakagami- m distribution approach was first tested on the published data and then used to develop the GIUH for Bhagirathi-Bhilangana River catchment. Based on the results of comparison with other approaches, it seems that Nakagami- m distribution-based GIUH can be a good substitute to other existing approaches.