[A-HW25] Near Surface Investigation and Modeling for Groundwater Resources Assessment and Conservation

[AHW25-P07] Modeling Saturated-Unsaturated Groundwater Flow in Taoyuan Region Considering the Influence of Laterite and Gravel Layers: Impact of Pond Recharge

*Li-Yuan Hsu¹、Jui-Sheng Chen^1,2 (1.Graduate Institute of Applied Geology, National Central University , Taiwan 、2.Center for Advanced Model Research Development and Applications, National Central University, Taoyuan, Taiwan)

キーワード：Thermal-Hydrology-Mechanic-Chemical (THMC) Software , Groundwater, Laterite, Taoyuan, Groundwater Flow Model, Ponds

Under extreme climate conditions, the uneven spatiotemporal distribution of precipitation has made groundwater a crucial source of stable water supply. The interaction between saturated and unsaturated zones is a key mechanism in groundwater flow and recharge processes. However, the unique stratigraphic configuration in Taoyuan characterized by a low-permeability laterite layer and a high-conductivity gravel layer complicates the recharge process. In particular, the region's distinctive ponds, as potential sources of groundwater recharge, have uncertain recharge mechanisms and efficiency, thereby increasing the uncertainties in water resource management. To address this issue, the present study employs THMC software to develop a groundwater flow model that accounts for the spatial distribution of laterite and gravel layers. This model simulates groundwater dynamics under various stratigraphic conditions, with a focus on the exchange mechanisms between saturated and unsaturated zones, and quantifies the impact of pond recharge. Initially, hydrological and geological data for the Taoyuan region are collected and analyzed to characterize the distribution of laterite and gravel layers and determine their corresponding hydraulic parameters. Key data including regional precipitation, pond water level fluctuations, and pumping rates are then incorporated into the numerical simulations. Different rainfall and groundwater level scenarios are modeled to investigate how varying geological structures influence water movement and exchange during the recharge process, as well as to assess the effects of pond recharge on groundwater level variations and recharge efficiency. The results of this study are expected to provide a more precise evaluation method for groundwater recharge, thereby offering a critical scientific basis for water resource management in Taoyuan. Furthermore, the findings will aid in the development of more effective recharge strategies to enhance sustainable water resource utilization in the face of extreme climate challenges.