Estimation of Flood Discharges for Various Return Periods at Kabini Dam Using Statistical Approach

Abstract

Determination of magnitude of floods for various recurrence intervals at a point serves a vital information to design any hydraulic structure, water resource managers in management of water, preparedness with regard to possible flood annihilation etc., An attempt has been made to gauge the design flood magnitude for various return period at Kabini dam located at H.D Kote, Mysuru subjecting the collected inflow data of 31 years to flood frequency analysis. Three statistical methods, namely: Log normal distributions, Log Pearson Type-III distribution, Gumbel's extreme value Type-I distributions are used in estimating the possible design flood discharges. The check for best fit distribution with the observed data is evaluated by Graphical technique and Parametric statistical approaches like Ftest, T-test and Z-test. In the present work for observed set of data, Gumbel's extreme value (Type-I) distribution fitted well revealing least deviation compared to other two distributions in both Graphical and Statistical techniques. Hence the magnitude of design flood for various return periods includes: 5, 10, 20, 50, and 100 years were calculated using Gumbel's extreme value (Type-I) distribution. The estimated design flood discharge helps in taking necessary precautionary measures and also in regulating the flow at the dam site when it is bound to occur.