The impact of groundwater discharge to the Hsueh-Shan tunnel on the water resources in northern Taiwan

Chiu, Yung-Chia; Chia, Yeeping

The impact of groundwater discharge to the Hsueh-Shan tunnel on the water resources in northern Taiwan | L’ impact de la décharge de nappe dans le tunnel Hsueh-Shan sur les ressources en eau au Nord de Taiwan El impacto de la descarga de agua subterránea hacia el túnel Hsueh-Shan sobre los recursos de agua en el norte de Taiwan 地下水向雪山隧道的排泄对台湾北部水资源的影响 O impacte sobre os recursos hídricos da descarga de águas subterrâneas para o túnel de Hsueh-Shan, no norte de Taiwan

2012

Chiu, Yung-Chia | Chia, Yeeping

The Hsueh-Shan tunnel is the fifth longest road tunnel in the world. During the excavation, the tunnel encountered several events of groundwater inrush, causing serious delay of the construction. Data on groundwater discharge to the tunnel were gathered from the monitoring system and their spatial and temporal variations were analyzed. The results of the integrated analysis of groundwater discharge and local precipitation indicated that the discharge increased rapidly when the cumulative rainfall exceeded 85 mm. The groundwater level recession rate after a rainfall event was found to be independent of rainfall intensity. A hydrogeological conceptual model was developed to simulate the long-term groundwater discharge to the tunnel. Sensitivity analysis was first conducted to identify sensitive parameters, and then the calibration process was accomplished by the automated parameter estimation method. The calibrated model was then used to evaluate the potential impact of tunnel excavation on the Feitsui reservoir; the average percentage loss of inflow to the Feitsui reservoir from 2006 to 2010 is estimated to be 1.74%. The developed model can provide a tool for evaluating the regional hydrogeologic setting and the influence of tunnel construction on water resources.

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