FLOOD FREQUENCY ANALYSIS FOR UNGAUGED SITES OF CENTRAL INDIA

Abstract

Flood frequency analysis aims at estimating the flood magnitude corresponding to required recurrence interval, at a project location. Regional flood frequency analysis is used for the estimation of floods at sites where little or no data are available, It involves the identification of groups (or regions) of hydrometeorologically homogeneous catchments and the application of a regional estimation method in the identified region. In the present study analysis of. the data of 116 sites of Central India using, L-- moments, indicate the superiority and versatility of the L-moments as• par1,.,cicr estimator for most of the distributions, as goodness of fit indicator for at site as well as regional distribution and for checking the homogeneity of the basins/area. I3 sed on the detailed statistical analysis - of the data, the regional flood formulae have finally been developed for. different subzones of zone 3. L-moments have been used to estimate parameters of various distributions such as Extreme Value type I (EVI), General Extreme Value (GEV), logistic, Generalised logistic, Generalised pareto, Normal and lognormal distributions. These distributions have been evaluated based on various criteria such as efficiency and L-moments ratio. Regionalization techniques depend on the degree of heterogeneity, intersite dependence and presence of outliers in the data set. Various homogeneity tests such as X-10 test, Revised Dalryrnple's test and MOM Cv tests are studied to judge the homogeneity of different subzones of zone 3 of India. Regional flood frequency analysis has been carried out using standardized L-moments for different distributions. Outliers are detected and treated based on Bulletin 1-7B and all the sites are cross correlated to know which of the sites are most correlated to study the Effect.