A customized resistivity system for monitoring saturation and seepage in earthen levees: installation and validation

Abstract

This work is based on the assumption that a resistivity meter can effectively monitor water saturation in earth levees and can be used as a warning system when saturation exceeds the expected seasonal maxima. We performed time-lapse ERT measurements to assess the capability of this method to detect areas where seepage is critical. These measurements were also very useful to design a prototype monitoring system with remarkable savings by customizing the specifications according to field observations. The prototype consists of a remotely controlled low-power resistivity meter with a spread of 48 stainless steel 20 × 20 cm plate electrodes buried at half-meter depth. We deployed the newly-designed permanent monitoring system on a critical levee segment. A weather station and an ultrasonic water level sensor were also installed in order to analyse the correlation of resistivity with temperature, rainfalls and water level seasonal variations. The preliminary analysis of the monitoring data shows that the resistivity maps follow a very reasonable trend related with the saturation/drying cycle of the levee caused by the seasonal variations of the water level in the irrigation channel. Sharp water level changes cause delayed and smooth resistivity variations. Rainfalls and, to a lesser extent, temperature seem to have an influence on the collected data but effects are apparently negligible beyond 1 m depth. The system is currently operating and results are continuously monitored.

Investigation on the Role of Water for the Stability of Shallow Landslides—Insights from Experimental Tests

“…Geophysical methods have been commonly used to assess the stability of slopes and embankments [27][28][29][30]. In particular, electrical resistivity tomography (ERT) has shown to be efficient in monitoring the variations of water saturation and detecting seepage zones for a variety of studies focused on hydrogeological issues (e.g., [31][32][33][34][35]). In order to obtain a better view of the processes leading to collapse, several experiments featured electrical resistivity tomography (ERT) measurements.…”

Tech-Levee-Watch: experimenting an integrated geophysical system for stability assessment of levees

“…A preliminary prototype of the permanent geoelectrical monitoring system (Arosio et al, 2017) was installed on an earthen levee of an irrigation canal near Mantova (northern Italy). The bed of the canal is covered by a partially deteriorated concrete liner and a lateral moat collects seepage water.…”

Image-Based Reconstruction and Analysis of Dynamic Scenes in a Landslide Simulation Facility

“…To monitor the variations in water distribution along the main axis of the slope we applied the DC-resistivity method by installing a miniaturized array of 48 electrodes. This method is normally used for geophysical investigations and in recent years its use as a permanent monitoring system has been tested by several authors for applications on landslides and artificial earth structures such as dams and levees (Arosio et al, 2017). Ultimately, two kinds of fibre optical-based sensors were buried in the soil in order to monitor precursory signals of displacements, which could indicate the onset of instability within the terrain during a landslide simulation experiment (Ferrario et al, 2016).…”