Water balance of Crimea for 2001–2021 based on ground and remote sensing data

Estimates of precipitation, evaporation, river runoff, potential evaporation and components of basin water storage were obtained for the territory of Crimea and a number of its river basins for 2001–2021. The period 2014–2021 was characterized by greater aridity compared to 2001–2013, namely a decrease in the precipitation and river runoff and an increase in the evapotranspiration. The streamflow balance tends to decrease from the upper parts of the catchment to the lower parts. The exception is the Belbek basin, where the area of runoff losses falls on the middle part of the catchment. Analysis of changes in measured and climatic runoff for two periods showed an increase in non-evaporation runoff losses in many mountainous and foothill areas, which is probably related to a decrease in groundwater inflow and an increase in water withdrawal. At the same time, it is possible that for the plain parts of the catchments of the Alma, Chernaya, Belbek and Kacha rivers, as well as the upper reaches of the Salgir, there was an increase in river runoff as a result of groundwater exploitation and further wastewater inflow into the rivers. The decrease in runoff within the Salgir basin by 0–40 mm can be partially explained by the closure of the North Crimean Canal in 2014. The estimated decrease in groundwater storage within the Crimea for 2003–2020 was of the order of 150 mm.