№ 1 (2024)

Seawater intrusions into coastal aquifers have been the object of study by hydrogeologists since long ago. A wide range of methods are used to predict the development of intrusions: analytical, numerical analytical and numerical. The purpose of this paper is to identify and evaluate seawater intrusion using a coastal groundwater intake as an example. The paper considers a coastal groundwater intake, where mineralization, total hardness and chlorides have increased due to intensive exploitation. Seawater intrusion is assumed to be the main reason for the groundwater quality deterioration. To prove the seawater intrusion motion, chemical sampling of water from the intake wells was carried out, which resulted in chlorine-bromine coefficient values indicating the presence of seawater admixture in fresh groundwater. The seawater intrusion was evaluated using numerical-analytical and numerical modelling. The estimation obtained by the analytical element method (GFLOW code) indicates the presence of seawater intrusion at the studied water intake. However, the analytical element method calculations provide the ultimate steady-state estimate of the intrusion development. Also, the method uses the assumption of a sharp freshwater-saltwater boundary. Numerical modelling provides a more realistic assessment. In building the three-dimensional numerical model, special attention was paid to the nature of the connection between the exploited aquifer and the sea. In the onshore part, the Quaternary aquifer is separated from the exploited aquifer by a clay layer with interbedded gravel and sand, but there is no data on the composition of sediments beneath the sea. To clarify their composition, profile numerical models were built in the FEFLOW program with different degrees of connection between the sea and the exploited aquifer. One of the models suggests a direct connection between the sea and groundwater through sand, while the other one is complicated by clay. According to the results of the profile models, the direct connection between the exploited aquifer and the sea was proved, which was taken into account in the construction of the three-dimensional numerical model. On the numerical model in the SEAWAT program, the change in the seawater intrusion position in different periods of water intake operation with different water withdrawal values was obtained, after which the calculation results according to numerical-analytical and numerical models were compared.

The article presents a model of aluminophosphate glass leaching, an analogue of the RW glass matrix, in static mode in the presence of bentonite. Parameterization of the model is based on experimental data. The model takes into account the kinetics of the glass matrix leaching and the transformation of bentonite mineral phases; sorption processes are also taken into account, as well as the inhibition of leaching by the precipitation of secondary mineral phases formed. The model demonstrates a small transformation of clay phases, as well as the formation of secondary phosphate phases and gibbsite upon leaching of glass in the contact zone with bentonite. The simulation was carried out in the PhreeqC software.

The methodology of protecting stationary objects (foundations of high-voltage network, cable road, overpasses, etc.) located on an active landslide slope is considered. A new approach to implementation of protective measures is proposed. It is based on the identified features of formation of new geological structures in the ground massif at the local area of technogenic impact. Dissipative geological structures develop in the landslide massif upon its thrusting on a immobile object. In particular, a core and boundary envelopes are formed at the contact with the frontal surface of the object, in accordance with the parameters of the latter. A methodology is proposed to ensure the flow of landslide masses around the object and its stability.

The article is focused on consideration of the engineering geological conditions of the area situated in the north-eastern residential part of the Ufa city (the capital of Bashkortostan). The majority of urban population lives in the Ufa-Belsko-Shugurovsky interfluve area. Exogenous hazardous geological processes are extensively developed there. The most wide-spread are karst, karst-suffusion, slope and erosion, as well as other engineering geological processes, which are manifested in the relief by sinkholes, craters, landslides, ravines and washouts. The research was based on a set of schematic maps compiled in 2013 according to archive data for the development of the Ufa master plan on a scale of 1:10000, as well as the updated versions of these maps [3]. The maps were created considering the state of the most problematic areas of geohazard activation. The occurrence of these processes was previously investigated by satellite and aerial images, and also in field by route survey as a part of reconnaissance. Archival geological information from the mining documentation was also used when compiling the maps. Engineering geological research and zoning territories with manifestation of karst, karst-suffusion, slope and other hazardous geological processes is proved to be relevant for the design of buildings and engineering structures. Currently, the engineering geological background data on the Ufa city territory is quite plentiful, and yet it remains uneven in the study area.

In the article, the authors considered the eastern part of the White Sea drainage basin within the administrative boundaries of the Arkhangelsk region. The aim of the study was to assess the potential predisposition of the main rivers inf the Arkhangelsk region to the drift and accumulation of sedimentary material (including polluting material) based on the calculation of the geomorphometric parameters of the relief. Analysis of pollution sources at the global (European Center for Environmental Destabilization), regional (Kola industry) and local levels (enterprises of the Arkhangelsk region) showed that the region is a recipient of pollution. The main route of pollutant transport is atmospheric, which is further transformed during floods. At the local level, the transfer is carried out due to the runoff of water. In all of the above options, the nature of the relief has a dominant role in the redistribution of pollution. Each type of transport can be taken into account and evaluated when calculating the geomorphometric parameters of the relief, which quantitatively demonstrate the potential predisposition of the territory to the drift, transit and accumulation of sedimentary material. The high role of drainless depressions as receivers and accumulators of pollution in the calculation of runoff into surface and groundwater and the transfer of material, both in ionic and suspended form, is shown. Based on the calculation of such parameters as Topographic Wetness Index (TWI), Terrain Ruggedness Index (TRI), LS factor, it was concluded that in the basins of such large rivers of the Arkhangelsk region as the Northern Dvina and Pinega, the processes of washout and transit, and, as a result, the pollution transfer prevail. In the basins of the Onega and Mezen rivers, accumulation of sedimentary material is predominant.

The paper describes the scientific and methodological fundamentals for the assessment of engineering geological conditions at platform areas for selection of environmentally friendly sites for allocating municipal solid waste landfills. By the example of Central Federal region of Russia and its part, Vladimir area, the algorithm of assessing the geoenvironment suitability is shown proceeding from the comprehensive consideration of geological structure, lithology of ground massifs, hydrogeology, and geohazards. The typological zoning of geoenvironment is performed in three stages: the first stage includes the small-scale zoning for the preliminary estimation of ground conditions of large regions at the federal level; the second stage comprises the medium-scale zoning for the comprehensive assessment of the territory according to the complex of natural conditions in order to distinguish favorable areas at a regional level; the third stage stands for the large-scale zoning for outlining and comparison of particular plots for MSW disposal proceeding from the score assessment of factors. For each distinguished type of ground conditions, the additional eningeering protective measures for landfill arrangement are assigned.

The experience in reclamation of disturbed lands in Kuzbass is summarized. The demand for studying the spatial distribution of soil composition and water content in soil at the technical stage of land reclamation is shown. Currently, there is a need to develop new methods for the reclamation of disturbed lands, aimed at ensuring further development of depleted areas. The goal of research is to develop a method for reclamation of lands disturbed by mining operations in Kuzbass, based on the use of applied geophysical technologies by the example of the Taldinsky coal mine. The proposed method is based on the zoning of the mined-out area proceeding from the results of applied shallow geophysical survey on the state of soils and their water content, which provides a new level of information interaction between the technical and biological stages of reclamation. The practical use of this method is to expand the possibilities of reclamation of disturbed lands for the development of rational environmental management.