Region-of-influence approach to a frequency analysis of heavy precipitation in Slovakia

摘要

The paper compares different approaches to regional frequency analysis withthe main focus on the implementation of the region-of-influence (ROI)technique for the modelling of probabilities of heavy precipitation amountsin the area of the Western Carpathians. Unlike the conventional regionalfrequency analysis where the at-site design values are estimated within afixed pooling group (region), the ROI approach as a specific alternative tofocused pooling techniques makes use of flexible pooling groups, i.e. eachtarget site has its own group of sufficiently similar sites. In this paper,various ROI pooling schemes are constructed as combinations of differentalternatives of sites' similarity (pooling groups defined according toclimatological characteristics and geographical proximity of sites,respectively) and pooled weighting factors. The performance of the ROIpooling schemes and statistical models of conventional (regional andat-site) frequency analysis is assessed by means of Monte Carlo simulationstudies for precipitation annual maxima for the 1-day and 5-day durations inSlovakia. It is demonstrated that a) all the frequency models based on theROI method yield estimates of growth curves that are superior to thestandard regional and at-site estimates at most individual sites, and b) theselection of a suitable ROI pooling scheme should be adjusted to thedominant character of the formation of heavy precipitation.