A Study On Groundwater Dynamics In Industrial And Mining Areas In Shanxi Based On GIS And FEFLOW

With the advantage of coal and the shortage of water, Shanxi is a province which is rich in coal and has been troubled by water problems. How to deal with the problem of water shortage is one of the most urgent problems to be solved in Shanxi, and the mechanism of groundwater processes in industrial and mining areas remains the key scientific issues to be resolved. Due to interference from mining activities, and over-exploitation of water resource, the groundwater system in industrial and mining areas has undergone a marked transformation with significant reduction in groundwater and continued drop in water level. What’s more, the natural storage environment of groundwater has been severely damaged, and the rules of supplement/runoff/discharge has been changed, resulting in serious ecological environment problems such as water pollution, spring cutoff and surface collapse more prominent, continues to increase.On the issues of water resource shortage and water environment deterioration in Shanxi mining area, this resesrch analyzed the natural conditions including meteorology, hydrology, geomorphology and identified the social economy conditions such as land use type, the present situation of coal mining, irrigation level, groundwater exploitation and so on. Then accumulated and arranged precipitation, evaporation, groundwater level monitoring data together with other related numerical data as data source. Finally the hydrogeological conceptual model and relative mathematical model were both established. On this basis, a new method that integrates GIS technique and FEFLOW model was used as platform to realize the numerical input of in\out on top\bottom and the hydrogeological parameters in mining area, for building the three-dimensional numerical model of groundwater preliminarily. By simulating and predicting the dynamics of mining groundwater under four different scenarios, there is a quantitative analysis of the impact of mining activities on groundwater dynamics, revealing its mechanism in groundwater system. Conclusions are as follows:(1) Monitoring data of groundwater level in 2008 was used as the initial level to identify and calibrate FEFLOW model. It was indicated that the simulated and measured water level in whole Jinci Spring reached a better fitting effect, the simulation of water level was relatively accurate, the accuracy of FEFLOW model can meet the required precision of study, the assigned parameters and model structure were nearly in line with the actual condition. In general, the model can be used for simulate and predict groundwater dynamics in industrial and mining areas.(2) In order to assess the sensitivity of groundwater level on mining activities, this paper used the factor transformation to analyze parameter sensitivity for mining intensity. The results showed that the absolute value of sensitivity coefficient of selected 28 monitoring wells mostly located in 0.2～1.2, with an average sensitivity coefficient reached 0.82. According to the classification of sensitivity, it can be judged to be grade Ⅲ, that is to say, the groundwater level is very sensitive to the mining activities, even extremely sensitive. Thus, mining intensity has a significant impact on groundwater system.(3) 2008-2018 were taken as forecast period to simulate and forecast the groundwater dynamics under four different scenarios. It indicated that the whole flow field and the motion trend of groundwater was not much changed when the intensity of mining reduced by 10%,30%,50%, and in the central and western regions, there is still a significant low center of water level which formed a groundwater drawdown funnel. However, the depth of funnel centre was rebound when intensity of mining reduced by 30%,50%. Equilibrium analysis of results showed that when the intensity maintained status quo or decreased 10%, groundwater systems are still in a negative balance, with its recharge less than excretion, when decreased by 30%, the system turned positive equilibrium, which keep increasing in pace with the decrease of mining intensity, resulting in significant increase of groundwater flow quantity and obvious rise of water level.This research revealed the dynamic rule of groundwater in mining area, analyzed the impacts of mining activities on groundwater systems, which provided a strong scientific and technological support for controlling the deterioration of water quality effectively and ensuring water security in mining area. It also provided the reference for the sustainable development of ecological environment in this area and even the whole mining area in Shanxi.