This figure shows the distribution of mean annual rainfall over the Caspian Basin for the period 1931-60 and demonstrates very clearly the regional variability in precipitation. Most meteorological stations have recorded a significant increase in precipitation since 1976, with changes in winter rainfall being more significant than changes in the summer, particularly in the Volga catchment.

Mean annual rainfall distribution

 These seasonal changes in rainfall have been investigated further by analysing the changes in monthly rainfalls observed at three representative locations between 1931-60 and 1961-95. This provides further evidence that it is the increased winter rainfall that is the most likely cause of the increased runoff from the Volga catchment since 1976.

Mean Monthly Rainfall, 1961-95