Groundwater Flow Monitoring via Combined Time-lapse Electrical Resistivity and Self Potential Data Tomography
Lige Bai1, Jing Li1*, Li Guo2,3, Hui Liu1, Jaiwei Tan1, Tianqi Wang1
1 College of Geo-exploration Sci. &Tech, Jilin University, Changchun, Jilin 130026, China
2 State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China
3 Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA
*Corresponding author: Jing Li,inter.lijing@gmail.com
Key words: Groundwater Flow Monitoring; Time-lapse; Electrical Resistivity Tomography (ERT); Self-potential (SP) Tomography
Funding Information: This work are supported by the Natural Science Foundation of China (41874134), the Jilin Excellent Youth Fund (20190103142JH) and the China Postdoctoral Science Foundation 2015M571366
Summary
Revealing the dynamics of groundwater movement in the vadose zone is crucial to groundwater management and artificial recharge. The traditional hydrographic surveys are usually indirect, costly, and infrequent. In this study, the groundwater flow characterization of a pumping experiment in Jilin University campus was monitored through combining time-lapse electrical resistivity tomography (ERT) and self-potential (SP) data tomography. The ERT datum depicts the spatial distribution of resistivity, which is related to the dynamics of soil moisture content during the pumping process. We are able to correlate hydraulic heads and SP signal during a decline and recovery groundwater level period leading to interesting perspectives in understanding the dynamics of complex groundwater flow. The SP method provides a direct way to estimate the potential field distribution, which can be further used to invert soil permeability. A total of 24 hours of time-lapse geophysical surveys revealed a significant increase in resistivity but a decrease in permeability during water pumping and groundwater recharge, representing the process of groundwater decline and recovery. Results derived from time-lapse geophysical surveys matched well with in situ monitoring of the groundwater level. The study demonstrates that the combined ERT and SP data can provide a direct and reliable way to monitor groundwater flow or other time-lapse hydrogeological surveys.