Meteorological and Hydrological Drought Assessment

The paper presents two indexes for the classification and space - temporal modeling of drought historical events during the year 1972 to 2014 in a 7 gauging station localized in a eastern part of Slovakia. Two different types of drought, namely: I) the meteorological drought is detected by SPI Standardized precipitation index - computed from monthly precipitations and II) the hydrological drought is detected by SSI - Standardized streamflow index - computed from monthly streamflow time’s series. These two indexes have the same mathematical background and can by computed by non-parametric approach as well as parametrical approach. For the non-parametric approach we have considered the Weibull plotting position to calculate the empirical cumulative frequency during the period of 1972-2014, while the parametric approach has been implemented considering the best theoretical probability distribution. Its selection is operated via the Kolmogorov-Smirnov test and the parameters’ estimation is made using the maximum likelihood method in a mathematical program EasyFitt. As case study we have considered seven monthly time series, 43 years long, in gauging stations namely: Bardejov, Červený Kláštor, Humenné, Ižkovce, Medzev, Svidník a Ždiar for streamflow, and stations: Bardejov, Červený Kláštor, Kamenica nad Cirochou, Vysoká nad Uhom, Štós, Tisinec and Skalnaté Pleso for precipitation, both in the period 1974-2014. The main contribution of this work is to reveal the spatial and temporal vulnerability of the studied area to drought and geographic representation of results that could be used for monitoring, minimized future negative effects and managed with water resources in studied river basins.