Лаборатория геологии техногенных процессов
Gorbunova K.A, Maximovich N.G., Blinov S.M., Kraev V.G. Factors determining underground water regime of Kungur Cave (the Urals)// The Proceedings of Karst-Water Environment Symposium.- Blacksburg, 1997. - P. 150
FACTORS DETERMINING UNDEGROUND WATER REGIME OF KUNGUR CAVE (the URALS)
K.A. Gorbunova, N.G. Maximovich, S.M. Blinov, V.G. Kraev
Kungur Cave is the only cave in Russia where regime observations on underground water level and composition have been conducted since 1934. The cave is located in the vicinity of Kungur City (Perm region), to the northwest of Ufimskoye plateau. The cave entrance is in the lower part of the northern side of Sylva river valley at the level of aggradation terrace. The terrace width near the cave entrance is 100-150 meter. Downstream, the terrace is pinched out and a valley borders the river. The total length of grottos and passages of the cave is about 5 to 6 kilometers.
The cave is formed in gypsum and anhydrite of Lower Permian Kungur state Iren horizon represented by alternation of gypsum-anhydrite and limestone-dolomite members. In the cave basement there occurs dolomite of Filippovsky horizon. Eluvial loam and detrital-shaly sediments, their thickness exceeding 10 meters, cover Lower Permian rocks. The field over the cave is complicated by the existence of numerous sinks. The largest ones are situated over large grottos.
Near the entrance the southeastern part of the cave is cold. In this location, various ice crystals, stalagmites, stalactites, columns, and overflow ice can be observed. The central and northwestern part of the cave are notable for the existence of more than 60 lakes. The cave is horizontal, grottos and passages are stretched mainly northeast and north-west.
Karst water in the cave occurs on the dolomite. Water containing rocks are cleaved through karstic gypsum, and anhydrite and detrial-shaly products of rock destruction. The aquifer is recharged by atmospheric precipitation which is absorbed by numerous sinks, water in the aeration zone (its thickness equals 70-80 m), and river water during flood periods. Karst water in the cave is exposed through three wells and underground lake basins.
The regime of cave massif karst water is formed under the influence of climatic, hydrologic, and geologic factors. The climate of the region is moderately continental, with average annual precipitation of about 500 mm. Maximum precipitation occurs in the summer time and snow cover lasts up to 180 days a year.
Climatic factors cause seasonal fluctuations of regime data. They influence the flood height and level of the river and karst waters. The influence of hydrological factors is expressed by close connection of cave karst water level with the Sylva River level. During the flood period, river water penetrates in cave massif for a short time by infiltrating through alluvial deposits of the first terrace or by inflow in karst rocks adjacent to the river. Lowest levels of river water (low-flow) are registered in the winter period and before floods.
The following geological factors influence karst water regime: the degree of fissuring and karsting of rocks, and their composition and condition of occurrence. According to G. N. Kamensky's classification, the cave massif is attributed to the near-bank type of regime. In heavily karsted areas the near-bank regime is changed by the absorption regime, and far away from the river it is changed by the divide regime.
Regime hydrochemical observations showed that after a flood period the mineralization of sulfate-calcic karst water decreases. Water becomes aggressive to gypsum and anhydrite. Seasonal fluctuations of rock and water temperature, air humidity, wind regime, level and mineralization of karst water are the factors that activate karst processes causing the evolution of the complex cave system.