Integrating Electrical Resistivity and Geomorphological Data to Identify Subsidence-Prone Areas

This study evaluates the effectiveness of Electrical Resistivity Tomography (ERT) for detecting and characterizing subsidence-prone zones along a section of the L-903 road between Alfarràs and Ivars de Noguera, in the province of Lleida. The area is geologically complex, with the road crossing Quaternary deposits underlain by evaporitic formations of the Barbastro anticline, primarily composed of gypsum and marls susceptible to dissolution and hydrocompaction.

A total of ten ERT profiles were acquired using a Wenner-Schlumberger array, providing resistivity data to depths of approximately 30 meters. The results revealed three distinct groups of subsurface resistivity patterns, corresponding to variations in lithology and the presence of dissolution features. Low-resistivity zones were associated with gypsiferous marls and potential subsurface voids, while high-resistivity anomalies suggested the presence of sand and gravel deposits or zones of incipient surface instability.

The integration of geophysical data with geological and geomorphological observations allowed the identification of specific road segments at greater risk of subsidence, particularly in areas intersected by drainage pathways. These findings underscore the relevance of geophysical surveys for the early detection of geohazards and highlight the importance of incorporating subsurface characterization into infrastructure planning and maintenance in evaporite-rich environments.