Features of the Karst Water Regime in the Skelskaya Cave (Ai-Petri Massif, the Mountain Crimea) and Their Hydrogeological Interpretation

The data of long-term monitoring (2012–2023) of hydrological (levels) and physicochemical (temperature, specific conductance) characteristics of karst water of the Skelskaya Cave are analyzed. Parallel observations in opposite parts of the cave (Western and Eastern lakes) revealed synchronous level variations but different dynamics of the temperature, specific conductance, and isotopic composition of water. The difference between the physicochemical parameters can be most clearly seen in flood events, which indicates the input into the cave of two karst water flows from different catchments. These were identified to be the Karadagskii and Tarpanbairskii recharge areas, which lie at different elevation levels and carry their waters along the Karadagskii fault towards Western and Eastern lakes of the cave, respectively. The comparison of water level variations in the cave with the discharge dynamics of the Skelskii spring, as well as the physicochemical and isotope characteristics during floods revealed a strong correlation between them. Therefore, the Skelskii spring is the main discharge site (drain) of the karst aquifer system of the Skelskaya Cave.