Abstract:

Based on the process of contamination filtering into soiladose zoneaquifer，geology，physiognomy and hydrogeology have been considered and indexes including depth to water，precipitation recharge，aquifer media，soil media，topography，impact of vadose zone and penetrability coefficients have been selected to establish DPASTIC index system of groundwater vulnerability assessment in Jiujiang City. The approach of fuzzy synthesis using DPASTIC indexes has been established according to fuzzy theory and method. It overcomes difference of rating and discontinuousness on index value and tries to seek optimization of rating and continuous change on parameters. The concept of index standard eigenvalue has been cited in order to determine index rating. Considering the data and information obtained in the study area，index standard eigenvalue matrix which sets corresponding to 10 linguistic classes used for determining the groundwater contamination degree of every parameter has been founded and relative optimization value been established. The map of groundwater vulnerability subarea has been drawn by MAPGIS soft. The distribution pattern of contamination is well consistent with groundwater environment quality forecasted and measured in this area，which has practical meaning for government agencies to set up prevention projects and management steps of groundwater contamination. It is considered that the method used in the present study has reference value to groundwater vulnerability assessment in similar areas.

Key words: groundwater vulnerability, fuzzy synthesis assessment model, DPASTIC index system, Jiujiang City