Repeated geophysical measurement: the basic principle of the GMS methodology used to inspect the condition of flood control dikes

Abstract

A Geophysical Monitoring System (GMS) is a modern and complex methodology of investigation serving as a complement to the classical techniques of inspecting the condition of flood control dikes. It is based on a combination of fast and cheap techniques for the basic description of long dike segments with more sophisticated methods serving for a detailed description of problematic dike segments. In particular, a combination of suitable geoelectrical methods -dipole electromagnetic profiling (DEMP) and resistivity tomography (RT) -is applied and, where appropriate, complemented by another independent method (mostly some of the seismic methods or microgravimetry). One of the innovations of the GMS methodology is the execution of repeated geophysical measurements at various levels of dike saturation with water. The interpretation of such measurements may detect the existence of anomalous seepage zones in the dikes. When performing the analysis of repeated measurements, it is important to eliminate the effect of "natural" (seasonal, climatic) changes in the measured parameters. In the case of the DEMP method which serves for the basic description of long dike segments it is a calculation of the so-called residual resistivity anomaly and mutual correlation of these anomalies in a series of repeated (monitoring) measurements.

Spatial Resistivity Mapping of Ureje Dam Floor, Southwestern Nigeria

“…They also evaluated the dynamic properties of the subsurface materials and evaluated the quality of the concrete in the dam interior using this technique. [16] employed geoelectrical measurement to identify seepages through embankments and dams. [17] successfully used electrical resistivity tomography (ERT) technique at Abu Baara earth dam in northwestern Syria to delineate potential pathways of leakage that occur through the subsurface structure close to the body of the dam.…”

Geophysical Evaluation of the Inner Structure of a Historical Earth-Filled Dam

“…Therefore, the non-invasive geophysical techniques have been widely used recently. The modern geophysical surveys, especially combination of different methods, are becoming fast and cheap option for the subsurface inspection [10,11]. The suggested techniques are electrical resistivity tomography (ERT) [12][13][14][15], ground penetrating radar (GPR) [16], electromagnetic methods [17] or rarely also seismic surveys [18].…”

Reservoir assessment using non-invasive geophysical techniques

“…In association with ERT, geophysical techniques such as electromagnetic scanning and self-potential have been suggested as non-invasive methods for examining internal embankments conditions (Sentenac et al 2013(Sentenac et al , 2017Jones et al 2014;Utili et al 2014;Ikard et al 2014;Bolève et al 2011). For instance, repeated geoelectrical measurement (SLINGRAM, ERT, SP) during the dry season and flood event was used for more precise interpretation of the seepages through embankment and dams (Benes et al 2011). Electromagnetic Slingram methods involving lowfrequency equipment (GEM-2, CMD, and EM31) for scanning embankments are far the fastest techniques (Viganotti et al 2013;Sentenac et al 2013) with GPR (Perri et al 2014).…”