Abstract: Based on the fuzzy comprehensive DRASTIC evaluation method , the vulnerability of unconfined water in Songnen Plain is evaluated.The main influence factors of the groundwater environment vulnerability in Songnen Plain are analyzed to construct the proper evaluation index system exactly and to determine the seven main hydrogeological parameters. The study area is then divided into 75 cells and the subordinate degree optimal matrix of each cell for different rank is constructed. The evaluation results show that the most vulnerable zone (the zone quite easier to be polluted) is only distributed in the high land area in the south of Wangfu-Fulongquan in Jilin Province; the vulnerable zone (the zone easily be polluted) is mainly distributed along the main streams, flood plains and low terraces of their main branches and the central low plain ; the least vulnerable zone is mainly distributed in the high plain area and the basaltic area in Wudalianchi.

Key words: DRASTIC method, fuzzy comprehensive evaluation, Songnen Plain, groundwater vulnerability