The objective is to analyze the dynamics of the underground water of a mine field based on the study of the geofiltration process of the rock mass disturbed by mining to achieve safe extraction operations as well as subsurface territories at the stage of the mining enterprise closure. Numerical modeling, based on a finite difference method under the conditions of multifactority and definite uncertainty of processes of transformation of technogenic environment of a mine field, helps solve a problem concerning underground water dynamics forecasting. A hydrodynamic model of the M.I. Stashkov mine was developed while solving option series of epignosis problems in terms of the chronology of mine field stoping. The abovementioned made it possible to identify regularities of the history of filtration, the capacity parameters of rock mass and the expansion of areas of heightened hydraulic conductivity as well as to evaluate qualitatively the water balance components of a carbonic watered formation and an overlying one. The stage of mining closure helped obtain the forecasting hydrodynamic solutions. The efficiency of measures, concerning reduction of water ingress into mine workings and the mitigation of surface ecological effects of mine flooding was evaluated quantitatively. It was determined that implementation of the water control procedures makes it possible to perform a 10–38% decrease in water ingress. In this context, they may be applied both independently and simultaneously. In terms of mine closure and flooding, a period of complete underground water recovery takes three years; in the process, surface zones of potential waterlogging and swamping are developed within the floodplain of Samara River, located at the territory of Western Donbas (Ukraine). The scientific novelty is to define regularities of hydraulic conductivity transformation of the rock mass of a mine field starting from the mine working roof fall, up to its compaction during the mine operation period. To do that, nonstationary identification problems were solved, using numerical modeling. The abovementioned makes it possible to improve the reliability of hydrodynamic prognoses and develop technological schemes to control water at the state of the mine closure.

To investigate pathways and concentrations of the most dangerous radionuclides entering the surface and groundwater in terms of hydrodynamic situation re-establishment in the zone of radiation-hazardous mine field objects in the southern wing of the Central Donbas coal industrial region for environmental assessment. Methods. Hydrodynamics and migration parameters characterizing the stage of mine workings' floodinghave been investigated. This phase is marked by the establishment of steady-state hydrodynamic regime with laminar groundwater filtration and radionuclide migration from the source of pollution to the river drainage. The parameters have been estimated on the basis of numerical modelling of geofiltration using available data from similar research and experimental studies. The resulting model has been calibrated by assessing the components of the water balance within the drainage area of the territory under research. Radionuclide migration pathways are defined by mathematical tools for mass-transfer calculation (MODPATH) using input parameters of the geofiltration model. To determine the concentration value of radionuclides entering the river drainage through the groundwater discharge, analytic calculations have been carried out. Facts and previous assumptions from different sources have been subjected to analytical comparison in order to outline the measures for control and technical settlement of possible threats and their ongoing assessment. Findings. Predictive modelling of the initial phase of hydrodynamic regime stabilization during mine working flooding has been performed. Possible concentrations of Sr 90 that are expected to enter the river drainage at the stage of groundwater level recovery to absolute marks (+120…+145 m) are calculated. It is found that the probability of Сs 137 ions migration is very low, which can be explained by the specifics of migration mechanism. It has been demonstrated that radionuclide migration pathways differ in the form of distribution and groundwater flow directions at the final stage of mine flooding. It has been established that the developed continuously operating hydrochemical model of the region together with the application of actual monitoring data obtained from the underground and surface hydrosphere within the government-controlled area could be considered a practical tool of possible environmental threats control. Originality. The research novelty is associated with the investigation of quantitative parameters of radionuclide migration within the abandoned coal mining areas on the basis of geofiltration modelling of current mine flooding conditions, when groundwater level reaches the critical mark, and the level stabilization process is accompanied by water resources recovery and water balance components transformation. Practical implications. The proposed research technique enables to forecast environmental consequences of coal mines' flooding in Ukraine and to assess the hydrosphere pollution not only with radionuclides but also with other chemical elemen...

The physicomathematical conjugation of filtration models of a flooded and an adjacent mine is carried out with a justification of methodological principles of analysis and prediction of a technogenic mode of groundwater in conditions of operation and flooding of a mine field. The identity of models and real objects is established as a result of solving a series of inverse problems and is confirmed by a water balance discrepancy of 0.003%, the convergence of water inflows in separate layers with a deviation of 5 – 12.5% and the coincidence of groundwater surface levels on models and data of a mode network. According to results of predictive solutions, it is established that dynamics of flooding of a rock massif within old stopes are more intensive than the restoration of a level of groundwater in a mine shaft. The options of technical solutions for curtailment of mining operations are justified, the ecological risks and costs of which can be optimized by constructing a water intake of technical (or drinking) water in the productive stratum of riverbed sandstones, as well as equipment for geocirculation heat supply systems using the capacitive resource of a flooded mine field.

The paper considers specific character of hydrogeological problems arising during the whole cycle of a mining enterprise operation; the most reliable their solutions are implemented in the context of numerical hydrodynamical models of mine fields. Basic approaches to schematize laminated carbonic formation through simplification of natural rock mass permeability have been substantiated; prediction algorithm of its changes during temporal transformation has been developed. Numerous identification problems solving in the process of modeling mine fields has helped understand that water inflow amount cannot be correlated with the extension of mining area. Within the areas with roof caving, permeability of carbonic formation is a time variable which value increases 10 – 15 times in the context of rock displacement, halves after 5 –10 years and nears natural values after 15 –20 years. In the context of Western Donbas, the modularized schemes have been tested while solving problems concerning filtration control within mine fields and their surface influence areas with high confidence of hydrogeological forecasts.

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