Modeling of river runoff formation in the mountainous Crimea under current and projected climate conditions

The ECOMAG runoff formation model was used to calculate physically based changes in the water regime of the rivers of the mountain Crimea in the XXI century using data from an ensemble of climatic models taking into account various global warming scenarios. The objects of the study were the rivers Chernaya, Belbek, Derekoika, Alma, Salgir, Burulcha, Tonas, Kuchuk-Karasu, and Indol. Models of natural river flow formation for the specified set of river basins were developed on the basis of homogeneous sources of information on hydrometeorological regime and land surface parameters. The hydrological models were verified by comparing actual and calculated daily and monthly water discharges at different hydrometric stations over a multi-year period. Then, the hydrological models were used to estimate scenario future changes in river runoff for a year, conditionally warm and cold seasons of the year using data from an ensemble of global climate models relative to the base period 2006–2020. Under the realization of any of the RCP scenarios in the near-term perspective for 2021–2050, as well as under RCP 2.6 and RCP 4.5 scenarios at the end of the XXI century, water resources deficit can be observed mainly in the river basins located to the east of the Salgir headwaters, however, without reaching catastrophic indicators. According to more aggressive climatic scenarios RCP 6.0 and RCP 8.5, at the end of the XXI century, the greatest reduction of river flow in the mountainous Crimea is likely, which will contribute to the development of water scarcity at the expense of atmospheric sources.