Sediment characterization in deltas using electrical resistivity tomography: The Ebro delta case

Abstract

Surface electrical resistivity tomography is a non-invasive and highly competitive technique that can be used to effectively characterize subsurface sediments for different purposes: geological, geotechnical, hydrogeological or subsidence problems. However, due to the strong effect of salinity on resistivity, sediments characterization in deltas (coastal areas) becomes a challenge. In this work, the results of combining extensive surface electrical resistivity tomography measurements and limited borehole logging and geological information in the Ebro delta plain is presented. The methodology used has been critical to reduce uncertainties in the interpretation of the ERT models, allowing to characterize the sedimentary architecture of the Holocene deposits in the Ebro delta plain up to about 60 m depth. The obtained geoelectrical models have been used for the construction of the Ebro delta 3D geological model prior to the delta plain subsidence assessment. Results also highlight the feasibility and capability of the electrical resistivity tomography technique to sediments characterization in extreme environments such as coastal areas and deltas. Additionally, the water quality distribution across the delta plain is also inferred.