REGIONAL FLOOD FREQUENCY ANALYSIS FOR CENTRAL INDIA

Abstract

Estimates of flood frequency quantiles are important in planning and design of hydraulic structures. Hence there is a need to seek for the most appropriate design estimator that would meet both safety and economic considerations of such structures. Over the years, a lot of research geared up towards achieving this goal. This has led to a general agreement, that at site/regional flood frequency analysis methods yield the most appropriate results. Cunnane(1988) conclude that Wakeby/GEV distribution with parameters estimated from regionally averaged standardised probability weighted moments are the most appropriate at site/regional and regional only flood quantile estimation methods. The ob_j,ec.t.i-.v-e- of the present study is to develop region curves for various subzone-s of Zone 3 of India and Zone 3 as a whole (coveri-ng river-basins of Central India) and to evaluate the performance o.f various.RFFA methods utilising the annual flood series (AFS) of various gauging sites of Zone 3. In this study at-site/regional and regional fl-ood frequency analysis has been carried-out for 116 sites drawn from 7 subzones of Zone 3 of India on subzone basis and Zone 3 as a whole basis using USGS, NERC and standardised probability weighted moments methods. For standardised probability weighted moments Wakeby distribtuion (4-parameters as well as 5-parameters), General Extreme Value (GEV) and Extreme Value type 1 (EV1) distributions have been used.