The Largest Lakes and reservoirs of Russia as a Priority Water Ressource for Society

Global change for the last 25 years drives to important changes in hydrometeorological regime in different regions, reflecting water resources change of the larges reservoirs and lakes of Russia and of lakes’ district with more than 460,000 small and middle size lakes (North-western part of Russia and Finland. Interdisciplinary approaches in water resources research include as methods of traditional hydrology and climatology as paleoclimatology and economy. Decrease in the water level of largest Lakes (Ladoga, Onega, Ilmen) by 35-70 cm has been registered over the 1990s, the warmest decade in the time series. At the same time inflow to the largest reservoirs of Volga River and of Kama River increased by about 30%. Only inflow to the Tsimlyanskoye Reservoir (River Don) exhibits tendency to decrease (10% lower than normal). In spite of the fact that reservoirs are water bodies with a regulated water level, catastrophic inflow to reservoirs or lack of inflow can cause serious economic and social after-effects. The observed increase of inflow to the Volga-Kama Reservoirs results in occurrence of situations when dams have not been able to regulate water storage carefully last decades. As a result, the inflow to reservoirs of the Volga-Kama cascade was 50 % higher in 1991 than mean value and vast areas have been flooded, 102 dams have been destroyed, total economic losses has been equal to 552,5 million rubles. Therefore we shouldn’t ignore the up-to-date and expected changes in the hydrological regime of inland water bodies as one of the most sufficient elements of the sustainable development of human society. A steady-state hydrological model has been developed for evaluation of changes in inflow to reservoirs and lakes with the progress of global warming (Lemeshko, 2002). The paleoclimatic reconstruction for global warming on 2 deg. have been used as empirical scenario. This scale of climate change corresponds to warm epoch of the past, considered as analog of future climate: the Last Interglacial-Eem (125 KA B.P.) (Borzenkova, 1992). Calculations have shown, that average annual runoff from the catchment of 71 Ladoga and Onega should increase for 80 mm, inflow to reservoirs of Volga- Kama cascade should increase by 35-60 mm, and to the Tsimlyanskoye Reservoir (River Don) for 50 mm. The combined assessment of regional peculiarities for the period of hydrometric observations with the data of paleoclimatic scenario of Last interglacial, makes it possible to decrease existing sufficient uncertainty in the forecast of future changes in the hydrological regime of lakes and reservoirs. Changes of lakes’ level and inflow to reservoirs can have both positive and negative consequences for economic and social life. And, decrease of lakes’ level and inflow to inland water bodies, as a rule, has negative after-effects. First of all it is connected with deterioration of water supply. The increase of river runoff and inflow to reservoirs and a high lakes’ level can have both positive and negative consequences. So, it is favorable for water supply of the population, an agriculture, water-power engineering, etc., especially for the southern regions of European Russia. But it can result in flooding settlements, agricultural lands, erosion of the reservoir’s coasts, to bogging and degradation of a soil cover.