Combined Numerical Simulation and Groundwater Depletion Sensitivity Analysis for Dynamic Pumping Management

The economy continues to grow in Taiwan, and water demand from both households and industry has also continued to increase, which has led to water scarcity problems rising throughout the island. Thus, groundwater plays an essential role as a backup to supplement water resources. Considering that overpumping might lead to groundwater depletion, land subsidence, and even water quality issues, drawing up a more efficient strategy for groundwater management is necessary. This study proposes a dynamic adjusting pumping rate based on the exceedance probability of the historical groundwater table and the regional sensitivity of the pumping rate. The sensitivity of regional groundwater depletion was calculated by solving a Jacobian matrix composed of various pumping scenarios from numerical simulations. The coastal region of the Taichung City of Taiwan was selected as the study site to test our method. The result indicated that the groundwater table drawdown affected by pumping was reduced from 3.0 to 0.17 m in the 2015 dry season. During the period, groundwater of approximately 750,000 t was provided. Similarly, 350,000 t of groundwater resources and only a 0.09 m drawdown were accomplished in the 2016 wet season. Thus, this study proposed a groundwater dynamic management rule based on the current water level that effectively improves the efficiency of using groundwater resources.