Future water availability in the largest freshwater Mediterranean lake is at great risk as evidenced from simulations with the SWAT model

Abstract Inter- and intra-annual water levelfluctuations and changes in water flow regime are intrinsic characteristics of Mediterraneanlakes. Additionally, considering climate change projections for the water-limited Mediterraneanregion, increased air temperatures and decreased precipitation are anticipated, leading to dramatic declines in lake water levelsas well as severe water scarcityproblems. The study site, Lake Beysehir, the largest freshwater lake in the Mediterranean basin, is – like other Mediterraneanlakes – threatened by climatic changes and over-abstraction of water for irrigated crop farming. Therefore, implementation of strict water levelmanagement policies is required. In this study, an integrated modeling approach was used to predict the future water levelsof Lake Beysehir in response to potential future changes in climate and land use. Water levelestimation was performed by linking the catchment model Soiland Water Assessment Tool(SWAT) with a Support Vector Regression model ( e -SVR). The projected increase in temperature and decrease in precipitation based on the climate change models led to an enhanced potential evapotranspiration and reduced total runoff. On the other hand, the effects of various land use scenarios within the catchment appeared to be comparatively insignificant. According to the e -SVR model results, changes in hydrological processes caused a water levelreduction for all scenarios. Moreover, the MPI-ESM-MR General Circulation Model outputs produced the most dramatic results by predicting that Lake Beysehir may dry out by the 2040s with the current outflow regime. The results indicate that shallow Mediterraneanlakes may face a severe risk of drying out and losing their ecosystem values in the near future if the current intensity of water abstraction is not reduced. In addition, the results also demonstrate that outflow management and sustainable use of water sources are vital to sustain lake ecosystemsin water-limited regions.