Impact of Changes in Short-Term Rainfall on Design Floods: Case Study of the Hnilec River Basin, Slovakia

Abstract The research aims to analyze changes in the predicted short-term rainfall intensities at the Telgárt climatological station and the subsequent use of these predicted rainfall intensities for estimating design floods. The area of interest selected is the upper Hnilec River basin in Slovakia. The research is divided into two parts: In the first part, the authors have focused on analyzing future seasonal changes and the trend of shortterm rainfall intensities and estimating the scaling exponents of short-term rainfall. In the second part, the observed and predicted short-term rainfall intensities have been applied to estimate the design floods in the study area, using the Soil Conservation Service – Curve Number method (SCS CN). The results indicate that for the future periods, there will be a shift in the rainfall maxima of about one week to an earlier period in July compared to the historical period. The changes in the short-term rainfall trends were detected in the 60-, 120- and 180-minute rainfall durations at the 90% significance level. The results of the design discharges predict higher values in the near future in the case of the 10- and 20-year return periods and higher values in the 50- and 100-year return periods for the remote future.