Hybrid Approach to Delineation of Homogeneous Regions for Regional Precipitation Frequency Analysis

Hybrid Approach to Delineation of Homogeneous Regions for Regional Precipitation Frequency Analysis Regional frequency analysis of heavy precipitation amounts based on the estimation of the parameters of a regional distribution function usingL-moments is adopted for the specific geographical-climatological settings of Slovakia. The paper focuses on the first step of the regionalL-moment algorithm (Hosking, Wallis, 1997), which is the delineation of homogeneous regions. Objective and process-based logical pooling techniques are used to form homogeneous pooling groups of rainfall gauging stations for regional frequency analysis ofk-day precipitation amounts (k= 1 to 5 days). Even though the delineation of homo-geneous regions by means of objective methods is generally accepted and recommended in the literature, it is concluded here that such a pooling of similar sites should not be carried out automatically in precipitation analysis. Instead, a combination of physical/geomorphological considerations and objective methods should be preferred.