Abstract: In order to prevent negative effects of tunnel construction on groundwater environment, we applied an evaluation system to a diversion tunnel project located near the east of Erhai Lake in Yunnan. On the basis of analysing the geological and hydrogeological conditions, we employed analytic hierarchy process (AHP) and fuzzy comprehensive evaluation method to select appropriate index weight and evaluate negative effects on groundwater environment. Results show that when the tunnel goes through Hecun segment of Dali, negative effects of level IV within 5 000 m on both sides of the tunnel and decline of groundwater are caused by tunnel construction. Ground subsidence, karst collapse, obvious surface flow reduction, and wellspring depletion will also take place. The research results offer reference for the construction and design of the diversion tunnel.

Key words: Erhai Lake in Yunnan, tunnel construction, negative effects on groundwater environment, AHP, index weight, fuzzy comprehensive evaluation method