Characterization of karst structures using quasi-3D electrical resistivity tomography

• Published in: Environmental earth sciences Vol. 78; no. 9; pp. 1 - 12
• Main Authors: Cheng, Qinbo, Chen, Xi, Tao, Min, Binley, Andrew
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2019; Springer Nature B.V
• Subjects: Anomalies; Aquifers; Biogeosciences; Catchment area; Channeling; Characterization; Confining; Earth and Environmental Science; Earth Sciences; Electrical resistivity; Environmental Science and Engineering; Geochemistry; Geology; Geophysical data; Geophysical methods; Geophysical surveys; Geophysics; Groundwater; Groundwater flow; Heterogeneity; Hydrogeology; Hydrologic models; Hydrology; Hydrology/Water Resources; Karst; Karstic environments; Mapping; Marlstone; Modeling; Remediation of Karst in a Changing Environment; Sinkholes; Spatial variability; Spatial variations; Terrestrial Pollution; Thematic Issue; Tomography; Two dimensional models; Watersheds; Weathering; Critical zone; Karst; 3D ERT; Resistivity
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-019-8284-2

Karst is characteristically complex, hydrogeologically, due to a high degree of heterogeneity, which is often typified by specific features, for example, cavities and sinkholes, embedded in a landscape with significant spatial variability of weathering. Characterization of such heterogeneity is challenging with conventional hydrogeological methods, however, geophysical tools offer the potential to gain insight into key features that control the hydrological function of a karst aquifer. Electrical resistivity tomography (ERT) is recognized as the most effective technique for mapping karstic features. This method is typically carried out along transects to reveal 2D models of resistivity variability. However, karstic systems are rarely 2D in nature. In this study, ERT is employed in valley and hillslope regions of a karst critical zone observatory (Chenqi watershed, Guizhou province, China), using a quasi-3D approach. The results from the extensive geophysical surveys show that there is a strong association between resistivity anomalies and known karstic features. They highlight the significance of a marlstone layer in channeling spring flow in the catchment and confining deeper groundwater flow, evidenced by, for example, localized artesian conditions in observation wells. Our results highlight the need to analyze and interpret geophysical data in a three-dimensional manner in such highly heterogeneous karstic environments, and the value of combining geological and hydrogeological data with geophysical models to help improve our understanding of the hydrological function of a karst system.