Groundwater Vulnerability Assessment Based On The Combine Of DRASTIC Model And ArcGIS

The Baiyinnuoer Mine in Chifeng City,Inner Mongolia is located in the arid and semi-arid region of the mainland.The region has less annual average rainfall,large evaporation,and lack of water resources.Human activities have a great impact on the groundwater environment.Mine mining activities can easily cause groundwater pollution.The assessment of groundwater vulnerability in the area is conducive to the prevention and control of groundwater pollution in the area,which has great practical significance.On the basis of field investigation and collection of geological,hydrological and meteorological data,the combination of GIS technology and the improved DRASTIC-GL model was used to determine the weight of each factor using the Analytic Hierarchy Process(AHP method),based on the groundwater vulnerability index of the study area.Size to partition.The main research content includes:(1)Through field surveys and detailed data collection,a clear understanding of the physical geography and characteristics of human activities in the study area was obtained;in addition to the selection of seven factors in the traditional DRASTIC evaluation model,land use(L)and the goaf(G)were also selected.Establishing a DRASTIC-LG evaluation model that considers the impact of human activities,and adopted a combination of ArcGIS and a groundwater vulnerability assessment model to evaluate groundwater vulnerability.(2)Using AHP method and comprehensive analysis method to determine the weight values of the factors,which were applied to the traditional DRASTIC model and the improved DRASTIC-LG model respectively;three evaluation methods were formed,and the evaluation results were basically the same as a whole:The southern and northern mountains are mainly low-lying areas and mildly vulnerable areas,occupying a large area,The sum of the percentages of the area exceeds 70%of the study area;moderately fragile areas,highly fragile areas and severely fragile areas are distributed in the Black River Valley and human activities.The region,where mining activity areas,tailings ponds,and some settlements are severely vulnerable,has the highest groundwater vulnerability index.(3)According to the distribution of cadmium in the sampling points,tests show that the three evaluation maps are basically in compliance with the test criteria of positive correlation between the vulnerability of the test area and the probability of containing cadmium in the sampling points in the area.The inspection criteria,the comparative analysis found that the best evaluation effect is the DRASTIC-LG model under the AHP method.The reason is that the integrity of the AHP method used to determine the factor weight value of the evaluation is better than that of the comprehensive analysis method and is more in line with the groundwater system.Integrity;in addition,the DRASTIC-LG model also considers the impact of human activities on the groundwater system and is more in line with the actual situation in the study area..(4)The results of DRASTIC-LG model evaluation under the AHP method show that the high-risk areas in the study area are distributed in the central residential area,the northwestern area and the west side tailings bank of the mining area,with an area of 5.8km~2;the severe risk areas are concentrated in the mining area.Heavy risk areas are concentrated in the mining area of the mining area,the tailings storehouse on the east side and some residential areas,with a sub-area of 1.6km~2.It is recommended to strengthen the monitoring of groundwater quality in the region and the protection of groundwater pollution.