Environmental risk evaluation of shallow groundwater and its spatial auto-correlation in lower reach of Liaohe River Plain

Field: Environmental Science (Physical Sciences)

As the economies are in the fast development, disasters occur more frequently. Evaluation, monitoring, and early warning of disaster risks are an important way to reduce the losses caused by the disasters. So it is one of the key topics in the current disaster research. As a major source of water in northern China, groundwater provides resource and ecological and geo-environmental functions. However, groundwater systems in northern China are being threatened by high population density, rapid urbanization and industrialization. Generally speaking, groundwater has been damaged to different degrees, which resulted in the decrease or complete loss of the functions of groundwater systems. So the research of groundwater environmental risk has great practical significance. In this article, the lower reach of Liaohe River Plain was chosen as a study area, and the shallow groundwater system was taken as a research object. The study area contains a large Quaternary groundwater system with characteristics typical of northern China. Social-economic and water environmental data of the Liaohe River Plain in 2012 were used in the study. Although many studies on groundwater have been conducted, few theories of groundwater environmental risk and methods of protection were developed at the groundwater system scale. Drawing lessons from modern hazard and environmental risk theories and methods, based on the definitions of groundwater environmental risks, we built an evaluation index system and an evaluation model for groundwater environmental risks from the aspects such as vulnerability, functionality, stress and adaptability. Using GIS spatial analysis method to evaluate the groundwater environmental risks in this region, we carried out spatial auto-correlation analysis. The results show that: 63.12% of the whole groundwater environment is facing a mid-level risk. In detail, the areas with extreme high risk accounts for 6.79%, the areas with high risk 18.96%, the areas with moderate risk 37.37%, the area s with light risk 21.98%, and the areas with slight risk 14.90%. Most high risk areas are mainly in the northeast of Xinmin City, Dengta City, west of Liaozhong County, parts of Heishan County and southeast of Linghai City. The risk of the study area shows a relatively high degree of positive correlation. The high correlation areas are mainly distributed in mid-east and mid-west of the high-risk areas and the northeast and southeast of low-risk areas. Uncertainty evaluation is an important part of the environmental risk analysis. But due to limited data, we didn't consider the indexes of randomness and fuzziness, which to a certain extent affects the scientific nature and reliability of the evaluation results. With constant improvement on the information sources, more studies will be done to include uncertainty index of groundwater environmental risk evaluation. The specific purpose of this study is to investigate measures to protect the three functions of the groundwater systems based on groundwater system risk evaluation. This study is of great significance to the enrichment of groundwater environmental risk theories and methods, and it also helps with making scientific decisions for the protection of the groundwater system of the lower reach of Liao River Plain and similar areas.