Grid-based Model of The Volga Basin
Abstract
The Volga is the largest river in Europe and is of great significance for the economy of Russia. The Volga basin, of about 1.4 million km2, displays a wide range of to- pography, hydrometeorology and water resource problems. Its cascade of 12 large reservoirs controls the river flow. The Volga contributes about 80% of the total water inflow to the Caspian Sea and thus forms the main influence on Sea level fluctuations. Variability in climate and climate change give uncertainty to the current and future availability and distribution of water resources in the Volga basin. This Volga model was part of a larger study that aimed to develop a realistic and consistent methodol- ogy, including the facility to take into account the effects of climate change scenarios for the year 2050, indicating possible changes in future river inflows to the Caspian Sea. The methodology involved examining flows and water demands on a 0.5 by 0.5 grid. This choice was a compromise between that needed to represent spatial variabil- ity and the availability of suitable data. The modelling approach was based on work aimed at examining water resources availability on a world-wide scale (Meigh et al., 1998). At a preliminary stage the main direction of flow for each cell is determined assuming that all the flow from one cell flows into one of the adjoining cells. Based on these flow directions, the order in which the cells must be processed is determined so that the flows from upstream cells have always been calculated before processing the cell into which they flow. The processing order also takes into account the artificial transfers between cells. Surface runoff is generated for each cell by using a rainfall- runoff model; the model chosen was the probability-distributed model (PDM) devel- oped by Moore (1985). The flows are then routed through the linked cells to estimate total runoff for each cell. The effects of lakes and wetlands, water abstractions, return flows, artificial water transfers, flow routing and transmission losses are also taken into account. The basic time step of the model is monthly, and 30-year time series of flows are generated. Additions to the model for the Volga basin were made so that it could compute the effect on runoff of snow accumulation and snowmelt, soil freezing and melting, interception losses of precipitation by forest cover, and flow control by large reservoirs. The grid model was configured for the Volga basin, consisting of 935 cells. Model calibrations were carried out on the baseline period 1961-1990 and good results were achieved. Simulations of future flows for the 2050s were made using sev- eral climate scenarios from a range of GCMs, along with scenarios of high, medium and low water demands within the basin for the same time horizon.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.1275T