NEW LOOK AT HYDROGEOLOGICAL CONDITIONS OF THE FEDERAL CITY OF SEVASTOPOL

Abstract

The relevance of the work consists in compilation of all available hydrogeological materials (published and fund) on the territory of the city of federal significance Sevastopol and drawing up in accordance with existing methodological recommendations the new generation scheme of hydrogeological stratification and a hydrogeological map for the first time in the last 50 years. The studied territory has a rich history from ancient times and as a consequence, year-round it is a favorite place in the tourist routes along the Crimean peninsula. The increasing flow of tourists and satisfaction of the current and future needs of the Sevastopol urban agglomeration in quality drinking water is one of the primary tasks of ensuring social stability, protecting health and increasing the life expectancy of the population (436 thousand people as of 01.01.2018). Currently, 9 water intakes (Orlovsky, Lyubimov, Rodnikovsky and others) are used in the city for the purposes of centralized household and drinking water supply. Most of them exploit the water-bearing complex of Miocene sediments. If one analyze the situation with the underground water supply of the city of Sevastopol as a whole, it can be stated that the approved operational reserves at operating water intakes are at best 30–40 %, with the exception of Inkerman water intake, where this figure reaches 90–93 %. But the issue of underground water supply and development of existing water intakes is not simple. Errors in the operation of the Orlovsky water intake in the 1980s have already led to disastrous consequences for the change in chemical composition of groundwater in the exploited aquifer. In this regard, the issue of underground water supply must begin with the creation of a modern hydrogeological model, which first of all implies the actualization of the hydrogeological stratification scheme and the hydrogeological map of the city of Sevastopol. The aim of the research is to reveal the features of the hydrogeological structure of the city of federal significance of Sevastopol on the basis of a detailed analysis of archival, published and field research, and to compile, in accordance with existing methodological recommendations, a new generation scheme of hydrogeological stratification and a hydrogeological map. Methods. The methods of I.K. Zaitsev, B.N. Arkhangelsky, E.L. Baskov, M.S. Altovsk, A.S. Ryabchenkov, N.V. Rogovskaya, M.R. Nikitin, B.E. Antypko and others researchers, the latest methodological recommendations of the Ministry of Natural Resources of Russia and VSEGEI on the compilation of hydrogeological maps and schemes of hydrogeological stratification, fund and published data were used. Results. The hydrogeological data on the territory of the city of federal significance Sevastopol is summarized and a hydrogeological map and stratification scheme were compiled. The data on the main aquifers and horizons in the region are presented. A brief description of their chemical composition is given. Two water-bearing structural stage (Mesozoic and Cenozoic) are distinguished in the region of investigation. They include 7 aquifers: 1) complex of Pliocene and Quaternary deposits – 8(N2-aQ); 2); Miocene – 8(N1); 3; 3) Paleocene-Eocene – 8(₽1-₽2); 4) Upper Cretaceous – 8(K2); 5) Lower Cretaceous – 8(K1); 6) Upper Jurassic – 8(J3); 7) the Upper Triassic–Middle Jurassic – 8(T3-J2). It is established that fractured-porous, fissured-karstic, fractured and pressure-fractured waters with total mineralization up to 1,5 g/dm3 are common in the lower (Mesozoic) aquifers, whereas in the upper (Cenozoic) aquifers mineralization varies from 0,4–0,5 to 10,3 g/dm3 (up to 35 g/dm3 in coastal areas). According to the chemical composition (within Shchukarev's classification) water composition is very diverse and there are 37 chemical types of water from fresh Ca-HCO3 to saline Na-Cl. The composition is dominated by ground waters of hydrocarbonate, hydrocarbonate chloride and chloride calcium and calcium-sodium types with total mineralization ranging from 0,16 to 2,63 g/dm3. Salinity of most groundwaters does not exceed 0,6 g/dm3.

Keywords

• groundwater
• hydrogeological map
• hydrogeological stratification
• sevastopol city
• crimea