Regional Flood Frequency Analysis Using L-Moments for North Brahmaputra Region of India

Abstract

Data of 13 stream flow gauging sites of the North Brahmaputra region of India are screened using the discordancy measure ( Di ) and homogeneity of the region is then tested employing the L-moments based heterogeneity measure (H) . For computing heterogeneity measure H , 500 simulations are performed using the Kappa distribution. Based on this test, it is observed that the data of 10 out of 13 gauging sites constitute a homogeneous region. Comparative regional flood frequency analysis studies are conducted employing the L-moments based commonly used frequency distributions. Based on the L-moment ratio diagram and ∣ Zidist ∣ -statistic criteria, general extreme value (GEV) distribution is identified as the robust distribution for the study area. Regional flood frequency relationships are developed for estimation of floods of various return periods for gauged and ungauged catchments using the L-moment based GEV distribution and a regional relationship between mean annual peak flood and catchment area. Flood ...