SOME FEATURES OF GROUNDWATER FLOW FORMATION AND CHANGE ON CERTAIN MAJOR VOLGA RIVER TRIBUTARIES OF TVER REGION (THE TVERTSA RIVER AND THE MEDVEDITSA RIVER)

Yakovlev Peter Ivanovich, Hidrologist of first category, Research center «Geoecology» (63 15 let Oktyabrya street, Tver, Russia), akva-petr.1947@mail.ru

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Background. The last estimation of the groundwater flow of the Tver region rivers was carried out in 1980s. At the present time there has occurred a necessity to re-estimate the parameters and and conditions of the underground inflow of certain rivers, where the water flow has changed due to anthropogenic factors.
Materials and methods. The author singled out two neighbouring river basins – the Tvertsa river and the Medveditsa river – differing by hydrogeological conditions and economic development of the territories. Estimation of the groundwater flow was carried out on the basis of low-water flow data according to hydrostations of the Russian hydrometeorological service and other agencies.
Results. The author specified more accurately the parameters of the groundwater flow and formation thereof on the rivers under investigation. The researcher gave a brief hydroeconomic characteristic of the river basins and determined the sections of outcrop of deep ground waters in the valleys of two Volga river tributaries, prospective for hydrogeological research.
Conclusions. The underground inflow change for the last 20–30 years has taken place on the lower part of the Tvertsa river, near the active Tveretsky and Mednovsky water abstractions. On the rest part of the territory under consideration no significant disturbances of the groundwater flow has been revealed.

underground waters, minimal low-water underflow, water discharge, increase of flow, discharge, spring-autumn, winter low water.

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