HYDROGEOLOGICAL CHARACTERIZATION AND REGIONAL GROUNDWATER CIRCULATION USING GIS AND MODFLOW MODELS: A CASE STUDY FROM KURUKTAG REGION, NORTHWEST CHINA
Applied Ecology and Environmental Research
In order to realize the evaluation of hazardous chemicals disposal sites in the Kuluktag region of Xinjiang, China, this paper conducted a numerical simulation study of the circulation of groundwater in the carrier of nuclide migration. Based on the hydrogeological survey in the field, a hydrogeological conceptual model of regional groundwater flow and a three-dimensional numerical model of regional groundwater flow were established. The finite difference method was applied to obtain the flow
... o obtain the flow velocity and characteristics of groundwater under various scenarios. By analyzing the sensitivity of the structure of water-containing medium and its parameters, this paper aims to explore the impact of the uncertainty of precipitation, water-containing medium structure and its parameters on the flow velocity and direction of regional groundwater, simulate the change of flow velocity and direction of groundwater in the study area, and predict the groundwater circulation rules in the long run measured in the unit of 10,000 years. According to the survey of stratigraphic lithology in combination with the analysis of groundwater dynamic field, geological structure and hydrogeology in the Kuruktag region of Xinjiang, the model of regional groundwater circulation is established, and the numerical model of three-dimensional groundwater flow is constructed to obtain the parameters related to the aquifer system. Based on the existing research results and risk assessment experience at home and abroad (Kendall, 1998; Singleton et al., 2005) , the groundwater flow numerical model is used to simulate the spatial and temporal distribution characteristics of groundwater flow under various scenarios, and the influence of the uncertainty of geological medium structure and parameters on groundwater flow is studied and explored. The variation rules of regional groundwater flow under long-term scale could be predicted through the mechanism and pattern of groundwater flow. (1) We use GIS (Geographic Information System) technology to integrate a large number of regional scale data (including geology, topography, spring location, and well information) into hydrogeological information data. The method not only accurately describes the hydrogeological conditions of the study area, improving the data management and efficiency, but also provides necessary data to support the establishment of regional groundwater models. (2) Due to the large-scale work area and the difficulties determining hydrogeological boundaries, SRTM DEM (the digital elevation model) data is used for hydrological space analysis, that is, the extraction of digital river network and the division of the drainage basin, so as to grasp the boundary of the whole basin. On the basis of hydrological analysis, the model boundary is determined according to the hydrogeological conditions, flow conditions and replenishment relationship of the work area. (3) According to the stratigraphic age and lithology, the regional groundwater permeability coefficient is divided. At the same time, considering the strong heterogeneity of the work area, the faults are separately characterized in the model to analyze the impact of faults on groundwater flow. (4) We aimed to establish a regional groundwater flow model by MODFLOW (Visual MODFLOW 2000 software), and correct the model through the measured groundwater water level so that the regional groundwater model can reflect the real groundwater flow field more accurately.