Author(s): Silvia Kohnova; Ladislav Gaal; Juraj Parajka; Jan Szolgay; Kamila Hlavcova
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Abstract: This study examines the applicability of the region-of-influence (ROI) method used as a mapping tool for the estimation of precipitation quantiles at ungauged sites in Slovakia. Its focus is set on the upper Hron River basin, which is located in Central Slovakia and encompasses 23 gauged sites. The annual maxima of 1-day precipitation totals derived from the daily records of precipitation totals in the period 1961–2000 are analysed. The ROI approach to a regional frequency analysis is an alternative to focused pooling techniques, in which unique groups of similar stations are pooled for the sites of interest, and their similarity is evaluated according to a certain set of site attributes. For the target area, three climatological characteristics that are expected to describe the country’s longterm regime of precipitation are used. Different mapping techniques (ordinary kriging, external drift kriging and inverse distance weighting) are applied to interpolate the selected site attributes into a regular grid network. The design precipitation of a 1-day duration and a 100-year return period is estimated in each grid point by means of the ROI approach, and the corresponding maps are constructed. The results are inter-compared with similar maps obtained by two other approaches: (i) direct mapping of the at-site quantile estimates and (ii) an expert’s hand-drawn isohyets map. Finally, several alternative settings and the application of these approaches in engineering practice is discussed.
Year: 2010