Study On Groundwater Vulnerability In Guan Zhong Basin

With the rapid economic development, the sharp expansion of population, and the acceleration of urbanization process, groundwater pollution became serious day by day. It led to decrease for water resources, which can be used, intensify water resources crisis, and influence economic development, also bring up dangers for eco-environments and human health. These problems also existed in Guanzhong Basin where human activities were frequent and environments were weak. Guanzhong basin is a national key exploit region, and an important industrial and agricultural base of Shaanxi province. The shortage of water resources and the groundwater pollution have become severe environmental problems. It is urgent to exploit rationally, manage and protect groundwater resources hi the new situation of the West Development. Therefore, it will be of momentous current significance to study groundwater vulnerability in this Basin that will provide scientific evidence for rational development and management of groundwater resources. Moreover, it will guide other regions. The contents of this paper are as follow:Firstly, this paper analyzed and summarized the current situation of the concept, classification, influencing factors, assessment methods, and mapping on groundwater vulnerability at home and abroad, and pointed out some problems existed in groundwater vulnerability researches.Secondly, this paper analyzed and studied geology, terrane and hydro geological condition in Guan zhong basin, the pollution state and the reason of groundwater pollution in Guan zhong Basin by the investigation of the field and the analysis of water samples. The result showed that the pollution of nitrate in groundwater had been very severe and the plane pollution had occurred.Thirdly, considering that groundwater nitrogen pollution is regional and severe in this basin, the objects to our research are the inherent vulnerability of groundwater and the specific vulnerability on nitrogen pollution of groundwater. Based on the analysis and studying different concepts on groundwater vulnerability at home and abroad, put forward the inherent vulnerability and special vulnerability.Fourthly, based on studying geology, terrane, and hydro geological condition deeply in this basin and analyzing synthetically concerned data at home and abroad, this paper analyzed and studied the influencing factors about the inherent vulnerability and special vulnerability of "Three Nitrogen" pollution of groundwater.Fifthly, taking into account the important role of the unsaturated zone and the special vulnerability of "Three Nitrogen" pollution of groundwater being concerned with the process of transportation and transformation about "Three Nitrogen" in the unsaturated zone, this paper designed and made experiments on the site, and studied the mechanism, of transportation and transformation about "Three Nitrogen" in the unsaturated zone of the loess.Sixthly, according to the process of transport, and transformation about "Three Nitrogen" in the unsaturated zone, this paper established the simulating models of these processes. In this paper , Computed water flow equation with finite difference method and solute transport equations with the Galerkin finite element method. In addition, the simulating models of the process of transport and transformation about "Three Nitrogen" in the unsaturated zone were identified and tested by the data from the site experiments.Seventhly, according to the analysis of influencing factors on inherent vulnerability, combining with analyzing concerned data at home and abroad, regarded geology, terrane and hydrogeology as the main control factors of inherent vulnerability. From these factors, we established the assessment index systems and the assessment standards of inherent vulnerability of groundwater, which was made up of lithology in unsaturated zone, stratum structure in unsaturated zone, terrane types, and the depth to groundwater, the vertical permeability coefficient of unsaturated zone, the conductivity of aquifer, and t...