Regional Flood Frequency Analysis of North-Bank of the River Brahmaputra by Using LH-Moments

In this study LH-moment proposed by Wang (Water Resour Res 33(12):2841–2848, <CitationRef CitationID="CR14">1997</CitationRef>) has been used for regional flood frequency analysis of the North-Bank region of the river Brahmaputra, India. Three probability distributions i.e. generalized extreme value (GEV), generalized logistic (GLO) and generalized Pareto (GPA) has been used for each level of LH-moments i.e. L, L<Subscript>1</Subscript>, L<Subscript>2</Subscript>, L<Subscript>3</Subscript> and L<Subscript>4</Subscript>. The regional frequency analysis procedure proposed by Hosking and Wallis (Water Resour Res 29(2):271–281, <CitationRef CitationID="CR15">1993</CitationRef>) for L-moments i.e. discordancy measure for screening the data, heterogeneity measure for formation of homogeneous region and goodness-of-fit test have been used for each level of LH-moments. Based on the LH-moment ratio diagram and ∣Z∣-statistic criteria, GEV distribution for level one LH-moment is identified as the robust distribution for the study area. For estimation of floods of various return periods for both gauged and ungauged catchments of the study area, regional flood frequency relationships have been developed by using the level one LH-moment based on GEV distribution. A comparative study has been performed between L-moments and LH-moments for the study area. It is observed from comparative study that the regional flood frequency analysis based on the GEV distribution by using level one LH-moment (L<Subscript>1</Subscript>) is superior to the use of L-moments. Copyright Springer Science+Business Media B.V. 2010