Comparison of mapping approaches of design annual maximum daily precipitation

In this study 2-year and 100-year annual maximum daily precipitation for rainfall–runoff studies and estimating flood hazard were mapped. The daily precipitation measurements at 23 climate stations from 1961–2000 were used in the upper Hron basin in central Slovakia. The choice of data preprocessing and interpolation methods was guided by their practical applicability and acceptance in the engineering hydrologic community. The main objective was to discuss the quality and properties of maps of design precipitation with a given return period with respect to the expectations of the end user. Four approaches to the preprocessing of annual maximum 24-hour precipitation data were used, and three interpolation methods employed. The first approach is the direct mapping of at-site estimates of distribution function quantiles; the second is the direct mapping of local estimates of the three parameters of the GEV distribution. In the third, the daily precipitation totals were interpolated into a regular grid network, and then the time series of the maximum daily precipitation totals in each grid point of the selected region were statistically analysed. In the fourth, the spatial distribution of the design precipitation was modeled by quantiles predicted by regional precipitation frequency analysis using the Hosking and Wallis procedure. The three interpolation methods used were the inverse distance weighting, nearest neighbor and the kriging method. Visual inspection and jackknife cross-validation were used to compare the combination of approaches.