Theme 5-6-Development of regional flood frequency relationships using L moments for south Bihar.

Abstract

Estimation of magnitudes of likely occurrence of floods is of immense importance for solution of a variety of water resources problems. Whenever, rainfall or river flow records are not available at or near the site of interest, it is difficult for hydrologists or engineers to derive reliable flood estimates directly. In such a situation, the regional flood frequency relationships or the flood formulae developed for the region are one of the alternative methods which may be adopted for estimation of design floods specially for small to moderate size catchments. In this study, regional flood frequency relationship has been developed using the L–moment based General Extreme Value (GEV) distribution utilizing the annual maximum peak flood data of 32 small to medium size catchments of South Bihar for estimation of floods of desired return periods for the small to medium size gauged catchments. The L-moment based regional flood frequency curves derived for the GEV distribution have been coupled with the relationship between mean annual peak flood and the catchment area and the regional flood formula has been developed for estimation of floods of desired return periods for the ungauged catchments of South Bihar.