Study On Groundwater Vulnerability In Lishui City Of Zhejiang Province

Groundwater vulnerability reflects the relative potential possibility of groundwater system to be polluted. The results of groundwater vulnerability research can provide a useful tool in land use planning, groundwater protection planning and groundwater quality monitoring. They can also help the pubic know more about groundwater pollution risk and have the idea of prevention taking priority in groundwater protection.Using the research experiences gained home and abroad for reference and taking Lishui city in Zhejiang province as the study area, an integrated groundwater vulnerability assessment based GIS technology is developed. The model has Parametric system methods as the basic, statistical method embedded to form an integrated model, that are used together to overcome the shortcomings of the single class of methods and to strengthen the objective and scientific foundation of the assessment results.The paper has divided the research area into two part: important part and common part, by the standards of classification for groundwater resources. The common part is analyzed as contrast. DRASTIC assessing model and the data of geological background such as geology,physiognomy,hydrology united together developed DRAMTIC assessing mode that suits to Lishui city.Seven parameters such as Recharge of rainfall infiltration,Depth to groundwater,Impact of the vadose zone media,Conductivity,Aquifer thickness,Mining intensity to groundwater,Topography are selected to form the vulnerability assessment factor system. Mining intensity to groundwater reflects outstandingly influence of human activities to groundwater vulnerability. The assessing cells are divided by village or town borderline, for the protection of groundwater resource to the locality. The rating system is confirmed according as DRASTIC assessing model and the rule which presents on the area. Principal component analysis and factor analysis are used to get the weighting system. Based on the established assessment system and GIS technique, groundwater vulnerability assessment is conducted in this area and a groundwater vulnerability distribution map is developed which is a useful tool for groundwater protection. The assessment results can reflect the capability of groundwater system to be protected and provide the direction for the planning department and the manage department of the groundwater resource.