Assessment And Prediction Of Groundwater Vulnerability In The Hun River Alluvial Fan Area

Hun River alluvial fan is located in the center of Liaoning Province, the groundwater hasbeen the region’s main source of water supply, which plays an important role in the economic andsocial development. In recent years, with the rapid development of industry and agriculture, andurban construction, the use of chemical fertilizers pesticides, garbage, and the industrial “threewastes” emissions increasingly. The pollution load enlarged gradually so that the groundwater isbeing severely polluted.Aquifer System has a natural protective effect to the pollutants permeate into groundwater,however, this natural protection reflects significant differences in the space. Groundwatervulnerability is an important indicator, which can quantify the groundwater system’s ability toresist the risk of contamination in an area. And conducting groundwater vulnerability assessmentnot only can identify the high-risk areas where vulnerable to pollution, but also can help tounderstand the impact of human activities on groundwater environment.This article relied on the environmental nonprofit industry research fund major projects-“Regional Groundwater pollution monitoring systems and the risk management keytechnologies”(Grant No:201009009), took Hun alluvial fan as the study area, based on theanalysis of regional geological and hydrogeological conditions, filtered out the impact of thegroundwater vulnerability evaluation index. Through DRASTIC and improved DRASTIC model,built the intrinsic and the special groundwater vulnerability assessment system on ArcGISplatform for the study area, and combined with hydrological forecasting, numerical simulation andother means to predict the evolutionary trends of shallow groundwater’s vulnerability, and furtherdrafted the shallow groundwater pollution protection zone. This thesis has made severalconclusions as follows:1. Shallow groundwater vulnerability assessment results show that groundwater in study areais mainly moderate vulnerability, and followed by the high vulnerability areas, these areasconcentrate in the river terraces which is together constituted by new fans and old fans of HunRiver’s. Sensitivity analysis of shallow groundwater vulnerability assessment models show thatgroundwater vulnerability index is most sensitive to groundwater depth, followed by land use.2. The result of shallow groundwater special vulnerability assessment in Hun River alluvial fan areas is quite consistent with the distribution status of groundwater organic pollution, theorganic contamination is more inclined to distribute in the high and moderate groundwatervulnerability regions, verifying that the established groundwater vulnerability assessment systemis reasonable, and the evaluation results can objectively reflect the basic characteristics of shallowgroundwater vulnerability.3. Groundwater flow forecasting model shows that compress the exploitation quantity ofgroundwater can effectively alleviate the problem of declining groundwater table, but with therecovery of groundwater levels, the depth to groundwater and thickness of the vadose zone willalso gradually reduced, and the pollutants in soils and vadose zone media will not have enoughtime to fully experience the adsorption, degradation and other reactions, so groundwater levels risein some degree will increase the risk of shallow groundwater contamination, some originalmedium groundwater vulnerability areas showing the evolution of trends to the high-level.