Groundwater Contamination Risk Assessment In Chang Zhu Tan City Cluster

Groundwater plays an irreplaceable role to maintaining the balance of ecology and the sustainable development of society. Compared to other sources of water, there are many advantages of ground water, such as small seasonal and annual variation, water stability, convenient exploitation, stable water temperature and difficult pollution. However, with the rapid development of science and technology as well as the progress of human society, groundwater is suffering from pollution damage in different levels. The polluted groundwater will cause less available resources, then restrict the development of society, harm human health, destruct ecological balance, and attract natural disasters which human beings can not overcome them. It is a economy and ecological method for man, economy and ecology to strengthen the protection of groundwater resources. Assessment study about pollution risk of regional groundwater will provide an important theoretical basis to avoid the groundwater to be polluted.Based on the analyses of previous researches and the definitions of pollution risk in groundwater, the definition of risk assessment about groundwater pollution is as follows: the protection of emergency in groundwater is the product of pollution graded index. This paper comprehensive analysis the factors which are the effect of pollution load caused by human activities which cause some risks in groundwater pollution, and the changed function of polluted water is suffering from pollution and the inherent resistance about water system. The classification results of disaster in pollution sources replace the probability of polluted groundwater. And groundwater vulnerability map and groundwater value map will be combined to form groundwater protection urgency map replacing the consequences of groundwater pollution in this paper. The high value in groundwater is polluted by the high hazard pollution source, then the risk of polluted groundwater will increase. According to the evaluation idea and taking the Chang Zhu Tan city group as an example, the problems, which exist in the process of development and protection of groundwater in Chang Zhu Tan city group, will be carried out risk assessment of polluted groundwater in the area.This paper makes a comprehensive analysis and summarizes the domestic and foreign previous studies about risk assessment, definition of risk, research methods and research status of groundwater pollution. Besides, it will point out the shortcomings of the current risk assessment research. The main types and spatial distribution of polluted groundwater sources in the Chang Zhu Tan city cluster are investigated in detail. By using the method of detailed classification and simple evaluation, the pollution disaster in groundwater in this area will be evaluated. Groundwater pollution disasters in the study area is divided into three levels: high, medium and low. Then a grade distribution map will be drawn and the picture of grade map about the result of groundwater pollution disaster will be illustrated.The paper analysis the factors which influences the vulnerability assessment of groundwater, through combining the specific circumstances in survey religion and the collected information and using DRASTIC evaluation system to evaluate the vulnerability of the water in Chang Zhu Tan city cluster. With the aid of the function of software MAPGIS about mapping and spatial overlay combination, the study separately carry out mapping and spatial analysis about the seven different evaluation factors, and then to eliminate the micro zoning. DRASTIC vulnerable index will be divided into five grades: highest, higher, medium, lower and lowest. According to the distribution of vulnerability, the vulnerability in the survey religion will be evaluated and analyzed.The value of groundwater is divided into "in situ value" and "exploitation value". Based on the analysis of previous researches and the combination of actual situation of the research area, this thesis comprehensive considers the value index and adopts four merit indexes which are density of population, per capita GDP, quality of groundwater and recoverable resources in groundwater. The quality of water will be calculated by the Nemero index method. MATLAB programming will be calculated the value index in weight and score. According to the value index, groundwater value will be divided into five types: highest, higher, medium, lower and lowest. Based on the function analysis of software MAPGIS, the value zoning map of groundwater in the study area will be obtained and the value of groundwater will be evaluated.The vulnerability map and value map of groundwater are combined in the software MAPGIS, and the protection urgency map about groundwater in the study area will be obtained. Both protection urgency map and classification of pollution hazards will be combined. According to the formula R=(D+V) * H to calculate pollution risk index in groundwater, the index from the high to low will be divided into five grades: highest, higher, medium, lower and lowest. Through the analysis of the reasons for pollution risk, this thesis will put forward some suggestions for risk management of the polluted groundwater in the area.