[M-GI25] Near Surface Investigation and Modeling for Groundwater Resources Assessment and Conservation

[MGI25-P04] Estimation of Transient Rainfall Infiltration Rates via Heat Transport Analytical Models for Subsurface Temperature-Depth Profiles

*Chia-Hao Chang¹, Jui-Pin Tsai¹ (1.National Taiwan University)

Keywords:heat transport, infiltration rates, parameter estimation, subsurface temperature

Due to geographical and climatic factors, the surface water resources in Taiwan are hard to preserve, which leads to water shortage. Therefore, groundwater is often treated as a stable source of water supply. Besides, climate anomalies prolong the drought period and increase the frequency. To reduce the risk of water shortage caused by drought, it is necessary to assess the changes in regional groundwater fluxes and properly manage it. However, the traditional method of measuring in-situ flow is time and cost consuming. In view of this, the method of using subsurface temperature as a groundwater tracer and estimating groundwater fluxes has been developed. This method is to use a heat transport model to analyze the measured temperature-depth profiles and then to estimate the groundwater fluxes through the optimization, so it can be called the Thermal Method. This method has the advantage that soil hydrogeological properties are unnecessary to know, but only the soil thermal properties are. This study builds an infiltration test field at National Taiwan University and estimates the field infiltration rate. The results show that under various rainfall patterns, the estimation from the Thermal Method agrees with the measurement from the flowmeter, even in temporal curves of the infiltration rate. This verifies the correctness of the Thermal Method and its feasibility of field application.