Research On Sensitivity Of Shallow Groundwater

Many urban and rural shallow groundwater surrounding environments in China are contaminated, causes deterioration of shallow groundwater quality and seriously affects the health of people and the sustainable development of the local economy, which becomes a critical environmental problem. The society are focusing on how to strengthen the ability to resist pollution and improve the quality of shallow groundwater, but the contaminative law of shallow groundwater is not very clear. Research and map-making on sensitivity of shallow groundwater are hot and front tasks in international hydrological geology, and also the prolog of groundwater pollution prevention and control work. The result can provide important basises for management decision in natural environment, community economy, etc.Shallow groundwater of Tai'an city is the main object of human activities, especially the quaternary pore water, which has the largest pollution load, the most sensitive to be polluted, and the most obvious control by hydrological, meteorological and hydrological geological structure.The thesis takes Tai'an shallow groundwater as an example, with the use of the GMS,GIS softwares and DRATMIC model, explores issues related to the sensitivity of shallow groundwater in-depth, and achieves some good results, major findings are as follows:(1) The thesis takes the natural and social attributes of shallow groundwater sensitivity as point of departure, with the combinative analysis of modern natural and social science theoretical viewpoints, clarifies the modern connotation of the shallow groundwater sensitivity: it means the orientation or possibility that pollutants reach the top of the aquifer on a particular location. Groundwater sensitivity can be divided into two types: one is the nature sensitivity, which is not considered the impact of pollution sources and the human activities, but only considered the impact of hydro-geological internal structure factors. The other is the special sensitivity, that is, a particular sensitivity of groundwater reflects specific contaminated source or human activities. (2) With the use of GMS technology platform and groundwater borehole data of Tai'an, this thesis achieves visualization of hydrogeological structure entities, intuitively shows the hydrogeological structure of the study area. The three-dimensional hydrogeological structure map shows that many places of the study area are coveraged by quaternary alluvial material, the thickness is from 8-27m in general, and greater than 50m in part.The lithology mainly has silty clay, sand, sand and gravel, and the weathering gneiss, mudstone, shale are very small in percentages.(3) By studying the present situation of the groundwater sensitivity evaluation system from home and abroad and the deficiency of the domestic shallow groundwater sensitivity study, the thesis constructs DRATMIC model, evaluates the shallow groundwater sensitivity (the orientation or possibility that pollutants reach the top of the aquifer on a particular location.) and grading Zoning of Tai'an, and it reflects the shallow groundwater sensitivity accurately.(4) With the sensitivity zoning based on DRATMIC model, the thesis uses GIS software map out the sensitivity zoning plans, so that results are more intuitive. The zoning map shows obvious regional characteristics of Tai'an shallow groundwater sensitivity, that is, the middle part, the east part and west part of the study area has three different degree of sensitivity, alluvial plains in central downfield mountain areas is the most sensitive, most vulnerable to be polluted; western low hilly area is the lowest sensitive, and is not vulnerable to be polluted;...