Application of the operator model of runoff formation to determine the average long-term values of maximum water discharge of spring flood in the Pivdenny Buh basin
In the context of Ukraine's integration into the European Union and implementation of the main provisions of Directive 2007/60/EC which implies assessment of potential hydrological risks, long-term factors of their formation, in particular the effects of climate change and the trend of river water regime changes should be taken into consideration. With this in mind, given the presence of both current long-term tendencies to reduction of runoff layers (volumes) and maximum discharge of water of spring flood across the Ukrainian rivers there is an important task to identify, using the modern initial data, both the average long-term values of these characteristics and different probability of their exceedance probability. For the first time, the authors of the study implemented an operator model of runoff formation to determine the average long-term values of maximum water discharge of spring flood in the basin of the Pivdenny Buh using meteorological characteristics (snowpack and precipitation) and runoff coefficients as basic parameters. The model was applied to determine the maximum runoff modules of spring floods for the rivers with a wide range of catchment areas affected by different physical and geographical conditions within the Pivdenny Buh Basin. Application of the operator model allowed the authors of the article to calculate and summarize all input parameters of the calculation model, including those obtained from observational data (snowpack, precipitation) and those that can't be measured by the hydrometeorological network (runoff coefficient, temporal irregularity coefficient and duration of surface inflow of snowmelt and rain water, transformational function of the flood waves layering under the influence of channel lag, coefficient of channel and floodplain regulation) for the rivers of the Pivdenny Buh Basin. The verifying calculation related to determination of the average long-term values of the maximum modules of spring flood runoff using the operator model showed satisfactory concordance with the initial data and this allowed recommending it for practical application for the rivers of the Pivdenny Buh Basin, including those that haven't been studied from the hydrological perspective.