Lumbroso, Darren · Davison, Mark

1 files · 6.5 MB · xlsxdeclared

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.

Lumbroso, Darren · Davison, Mark

2 files · 27 MB · xlsxdeclared

The hydrological model of the Volga River basin runs on a monthly time step. For each month, net precipitation is calculated as precipitation minus evaporation and converted to runoff using a delay function that includes contributions from the current month and up to four antecedent months. This formulation represents the aggregate effects of snow and ice storage, soil retention, groundwater contribution and river travel time using a small number of calibrated parameters. Runoff was separated into a rapid surface component, representing 80% of runoff, and a delayed groundwater component, representing 20%. The model was used to provide inflows to a Caspian Sea water balance model. Flows in the Volga River Basin are regulated by the Volga-Kama hydropower cascade which comprises 12 large dams and reservoirs constructed between the 1930s and 1980s The hydrological routing model of the River Volga can be used to route flow through the Volga-Kama hydropower reservoir cascade using a monthly flow routing model that represents constant minimum releases for hydropower and environmental flows, and spillway discharge when storage capacity is exceeded. Reservoir inflows were estimated based on the contributing catchment areas and simulated runoff volumes.