Kształtowanie się zwierciadła wód gruntowych na warszawskim odcinku Wisły

Abstract

Kształtowanie się zwierciadła wód gruntowych na warszawskim odcinku doliny Wisły analizowano w warunkach ekstremalnych. Główny wpływ mają przede wszystkim zmienne stany Wisły, a na terenie Warszawy również urbanizacja. Zasięg wpływu Wisły na wahania zwierciadła wód gruntowych jest zmienny. Wpływ ten znacznie ogranicza zwarta zabudowa miejska. Dwukrotnie zmniejszają się wieloletnie amplitudy wahań zwierciadła w stosunku do terenów nie zurbanizowanych. Trwałe obniżenie zwierciadła wód gruntowych pod wpływem urbanizacji ocenia się średnio na ok. 0,4 m. Nie obserwuje się wyraźnych korelacji stanów zwierciadła wód gruntowych z opadami atmosferycznymi.THE FORMING OF GROUNDWATER TABLE AT THE WARSAW SECTION OF VISTUU VALLEY On the basis of the measurements of the unconfined ground water table of the Quaternary horizon in the course of many years, the changes in their forming, mainly under the influence of Vistula River and the urbanization of Warsaw, were analysed. The ground water exists in the sandy-gravelly sediments of Pleistocene and Holocene. The forming of the ground water table was analysed in the extremal conditions of water levels. The changing levels of water in Vistula form an essential factor deciding on the extent of the influence and the amplitude of fluctuations of the ground water table in the zone of terraces immediately adjacent to the river. At the whole section of the valley, the influence of Vistula on the ground water table is changing and reaches the distance of 100-3000 m from the flood banks. In the urbanized area it is smaller and amounts to 100-1750 m. During the time in which Warsaw was beeing built the natural environment was gradually degraded. It is especially evident in the lowering of the ground water table and the pollution. In the area of dose city buildup the amplitudes of fluctuations of the ground water table counted for many years diminished twofold in comparison with the non-urbanized area. The value of permanent lowering of the ground water table at this area is estimated at 0.4 m, but in the area where the new blocks of houses with deep drainage are built, at over 0.4 m. At many sites in Warsaw significant spreading of the cones of depression in the ground water table was found, caused by the drainage of the deep foundations dug during the construction of blocks of houses, or as the result of Quaternary ground water exploitation by the wells drilled for the use of the manufacturing plants. In the urbanized area the distinct correlations of the fluctuations of the water table with the atmospheric precipitates were not observe