Flood Frequency Analysis Using Mixture Distributions in Light of Prior Flood Type Classification in Norway

The fundamental assumption of flood frequency analysis is that samples are generated by the same generation mechanism (FGM). However, events usually triggered interaction meteorological factors and watershed properties, which results in different FMGs. To solve this problem, researchers have put forward traditional two-component mixture distributions (TCMD-T) without clearly linking each component distribution to an explicit FGM. In order improve physical meaning seasonal snow-covered areas, ratio rainfall volume (referred as rainfall–flood ratio, RF) method was used classify distinct FGMs. Thus, weighting coefficient determined advance based TCMD (TCMD-RF). TCMD-RF model applied 34 basins Norway. showed types can be divided into rain-on-snow-induced flood, snowmelt-induced rainfall-induced flood. Moreover, design associated uncertainties were also estimated. It found reduce 20% compared with TCMD-T. superiority attributed its clear classification FGMs, thus determining coefficients optimization simplifying parameter estimation procedure distributions.