The wastes of mining resources usually have very large quantities, in which the granular size of the wastes is very fine and the moinsture contents or proceesing water are very high. Because of chemical compounds in the processing water, serious environmental problems, surface and subsurface water contaimination will be resulted from the leakage of proceesing water if the stack of the wastes is not treated properly. Due to the key functions of groundwater in the environmental systems, the assessment of tailings stacks on the impact of groundwater will be of great importances. However, structured grid in the numerical simulation models will not be appropriate to match the irregular inner and outer boundaries To evaluate the influences of tailing stacks of mining industries on the groundwater in complicated geological regions，it is necessary to understand the spatial variations of groundwater under the impacts of the tailing stacks. The development of numerical models capable of reflecting the geological complexity, with high stability and accuracy is very important. Therefore, in this paper, a completely implicit finite volume method (FVM) based on unstructured grid systems has been proposed. A case study was carried out in Guizhou province of China. The feasibility and accuracy of the numerical model have been validated through a comparison made between the simulated results and the data of boring holes. The influences of tailing stack in Guizhou on the regional groundwater have been revealed by comparing the spatial differences of groundwater with and without the impact of the tailing stack. Results indicate that the numerical model proposed is adapt for the groundwater simulation or the assessment of pollutants on the regional groundwater.
