Caspian Sea water balance model

A process-based monthly water balance model was developed to simulate changes in Caspian Sea water levels under both historical and future climate conditions. The model represents the Caspian Sea and the connected Kara-Bogaz-Göl (KBG) lagoon as coupled storage elements linked by a hydraulic exchange term. At each monthly time step, river inflows, direct precipitation, evaporation, groundwater and residual exchange fluxes, Volga Delta losses, and KBG exchange are converted into volume changes. The updated storage volume is then translated into water level using interpolated hypsometric area-volume-elevation relationships. The model incorporates historical river flow data from the basins draining into the Caspian Sea, together with time series of precipitation and evaporation.