Simulation and evaluation of the spatial heterogeneity of shallow-groundwater environmental risk in an urban–rural fringe of megacity: a case study of Shenyang city, northeast China

Shenbei district of Shenyang city, Liaoning province, northeast China is a typical urban–rural (peri-urban) fringe of a megacity that is undergoing rapid urban expansion and the intensification of agricultural management, which threatens the quality of shallow groundwater in the area. This study selects proper indices relevant to vulnerability, stress, function, and adaptability based on the results of groundwater monitoring and the collection and processing of hydrogeological data. Based on the theory of natural disaster risk, an evaluation index system was then established, followed by constructing a groundwater environmental-risk assessment model. Next, the model was used to perform environmental risk grading and spatial pattern assessment on the groundwater based on the statistics and spatial analysis function of ArcGIS. The assessment results were then subjected to a correlation analysis with land use indices and socioeconomic indices, to explore the effects of natural geological conditions, urban expansion and intensive agricultural management on groundwater environment. The results of the study will provide support for land use optimization and water environmental management decision-making during the development and construction of the urban–rural fringe of the area. The results of the study showed that: (1) the spatial distribution of groundwater environmental risk of the Shenbei district is similar to that of groundwater vulnerability. At present, geological conditions are still the main influential factors of groundwater environmental risk in the region; (2) the scale and intensity of urbanization and intensive agricultural management have shown an obvious potential risk to the groundwater environment; (3) the large area paddy fields in the northwest have certain ecological function value, which should be further protected to ensure a win–win situation of agricultural production and environmental safety; (4) it is necessary to put more environmental protection efforts such as ensuring natural vegetation protection, strengthening artificial afforestation, and increasing the number of waste water treatment facilities during the urbanization process, as these measures are significantly effective in maintaining the groundwater quality.