Combining multi-source data to identify the paleochannel system in the saltwater intrusion area

Abstract

The paleochannels in coastal areas may be the priority channels for saltwater intrusion, and identifying paleochannels is important for revealing the pollution mechanisms of coastal zone aquifers and protecting groundwater resources. The use of electrical methods to identify paleochannels has become common. Still, the highly dynamic hydrological characteristics of saltwater intrusion area and the differences in the conductive properties of saltwater and freshwater increase the uncertainty of the interpretation process. This study combined groundwater numerical simulation data, hydrochemical data and stratigraphic data to construct an electrical model of the paleochannel, which provides a reference for the interpretation of paleochannel using ERT data. The paleochannel electrical model constructed by combining multiple sources of data reflects the spatial heterogeneity of resistivity values of paleochannel in different seasons and at varying levels of saltwater intrusion, making the identification of paleochannel in saltwater intrusion areas more accurate. The results show that the paleochannel shows high resistivity anomalies relative to the background stratigraphy in brackish water areas, and low resistivity anomalies relative to the background stratigraphy in freshwater areas. Combining the paleochannel forward model with ERT data can effectively identify the paleochannel in saltwater intrusion areas.

Keywords:

• Saltwater intrusion
• groundwater numerical simulation
• geophysical forward modeling
• paleochannel
• electrical resistivity tomography (ERT)

Acknowledgments

We thank Jian Ma from Shandong Provincial NO.4 Institute Of Geological and Mineral Survey for the help in preparing this manuscript, collecting field data, and conducting geological survey.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is financially supported by the Open Research Fund of Key Laboratory of Coastal Science and Integrated Management, Ministry of Natural Resources under Grant (2021COSIMQ008).