Vertical groundwater flux estimation from borehole temperature profiles by a numerical model, RFLUX

• Published in: Hydrological processes Vol. 33; no. 11; pp. 1542 - 1552
• Main Authors: Li, Shaoheng, Dong, Linyao, Chen, Jianyao, Li, Rui, Yang, Zhigang, Liang, Zuobing
• Format: Journal Article
• Language: English
• Published: Chichester Wiley Subscription Services, Inc 30.05.2019
• Subjects: Air temperature; Boreholes; Boundary conditions; China; Exact solutions; Fluctuations; Flux; Groundwater; Groundwater flow; Groundwater management; Groundwater resources; heat; heat tracer; Hydrologic data; Leizhou Peninsula; Mathematical models; nonlinear initial condition; numerical model; Numerical models; observed GST and SAT; Profiles; Resource management; Resource utilization; Surface temperature; surface warming; Surface-air temperature relationships; Temperature effects; Temperature profile; Temperature profiles; tracer techniques; Tracers; velocity estimation; Water flow; Water resources; China
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.13420

We developed a numerical model, RFLUX, which uses the heat tracer method for vertical groundwater flux estimation, and applied it to the Leizhou Peninsula, South China, to provide information to inform local groundwater resource utilization and management. The temperature–depth (TD) profiles of 24 boreholes, along with the observed ground surface temperature (GST) and surface air temperature (SAT) series in recent decades, were collected in this area. Underground TD data demonstrated the capacity to identify groundwater flow patterns, and local GST and SAT data demonstrated a strong correlation with each other over monthly, seasonal, and annual scales. In the RFLUX model, the average GST and SAT series were applied as an upper boundary condition, and a nonlinear initial condition was set using an analytical solution from the literature. The model results of selected TD profiles demonstrated that the annual vertical groundwater flux was about 0.15 m a−1, which tended to be overestimated if a linear initial condition was used. This model can be easily applied with minor modifications, considering its clear purpose and simplicity.