[Groundwater Pollution Risk Assessment in Plain Area of Barkol-Yiwu Basin]

Groundwater pollution risk assessment is an important part of groundwater pollution prevention and control. Taking groundwater in the plain area of Barkol-Yiwu Basin as the research object, the DRSTIW model was constructed to evaluate groundwater vulnerability. According to the survey data of contaminated sites and land use types, point source and non-point source pollutions were classified, and the groundwater pollution load was evaluated. The primary value, economic value, and ecological value of groundwater were considered to evaluate the functional value of groundwater. The groundwater pollution risk assessment map was generated by using the map algebra function of ArcGIS software. The ROC curve was used to verify the risk assessment results of groundwater pollution. The spatial distribution of cold and hot spots of groundwater pollution risk was obtained by calculating the G index, and the change in hot spots was quantitatively analyzed by combining the center of gravity and standard deviation ellipse. The results showed that the groundwater vulnerability was generally low. The gentle terrain slope, shallow groundwater depth, and strong aquifer permeability made it easy for pollutants to enter the aquifer, resulting in high groundwater vulnerability in the northwest of Santanghu Town, the southeast of Dahongliuxia Township, and Kuisu Town in Barkol County. The groundwater pollution load and groundwater functional value were generally low, whereas the point source and non-point source pollution caused by industrial and agricultural production and life would increase the groundwater pollution load in local areas, and the human economic activities and habitat quality levels would affect the distribution of high groundwater function value areas. Groundwater pollution risk was generally low; very high and high pollution risk areas only accounted for 6.8% of the study area, mainly distributed in Naomaohu Town and Yanchi Town of Yiwu County, Kuisu Town, Shirenzi Township, Huayuan Township of Barkol County, and Hongshan Farm of Corps. The shallow groundwater depth, strong permeability of soil surface and vadose zone media, poor adsorption capacity, and concentrated distribution of pollution sources made it easy for pollutants to migrate and enrich in these areas. Under the dual influence of high vulnerability and high pollution load of groundwater, the risk of groundwater pollution in local areas increased. Affected by human activities, there was a certain spatial agglomeration of groundwater pollution risk, and the overall trend was from northwest to southeast. The results of groundwater pollution risk assessment provided a scientific reference for the division of groundwater pollution prevention and control areas.