Abstract: Scientific prediction on impacts of tunnel constructions on groundwater can effectively avoid tunnel water inrush disasters and reasonably protect and allocate groundwater resources.The Qianchishan tunnel to be built in the Dadu River-to-Minjiang River Water Diversion Project will directly expose the karst aquifer of Xiangshuixi Spring.The water source composition of Xiangshuixi Spring is analyzed by water balance method, and the relationship between the amount of water inrush in the tunnel and the flow change of Xiangshuixi Spring is predicted by analytical methods.A three-dimensional groundwater seepage numerical model is constructed to simulate the evolution of groundwater flow field during the tunnel construction.The results show that the water of Xiangshuixi Spring is mainly from karst water, among which Yangxin Formation (P₂y) limestone and Devonian (D_2-3) limestone account for 63%~65%, and Dengying Formation (Z₂€₁d) dolomite accounts for 20%~22%.The water inrush of the tunnel in the karst section is predicted to be 9 208~36 907 m³/d, resulting in a 23%~62% reduction in the flow of the Xiangshuixi Spring.The groundwater level along the tunnel would reduced to 850~1 250 m after one year of construction, the soluble rock section would reduced to 1 050~1 200 m, the maximum drawdown would be 180 m, and the drawdown of Xiangshuixi Spring would be 10 m.After one year of tunnel construction, the flow rate of Xiangshuixi Spring would decrease to 17 751 m³/d, 26% lower than that of natural state.After 120 days since the tunnel closure, the flow of Xiangshuixi Spring would recover to 91% of the natural state.The research results can provide theoretical support for the prevention and control of water inrush disasters in Qianchishan Tunnel and the protection of groundwater environment like Xiangshuixi Spring.