Experimental ERT Monitoring for Evaluating Seepage Vulnerability in Earthen Levees: A Case Study of the Tatarena Stream.

Earthen levees represent one of the primary structural measures for flood protection in floodplain areas. However, they can paradoxically increase hydraulic risk by fostering a false sense of security among the exposed population and urban planners (Castellarin et al., 2011). Moreover, these structures are susceptible to failure through various mechanisms triggered by physical processes during flood events, including overtopping and seepage or piping (Palladino et al., 2019).

Monitoring levee conditions using non-invasive geophysical techniques, such as Electrical Resistivity Tomography (ERT), is a highly effective tool for assessing internal structural integrity and detecting potential weaknesses. Such approaches can provide early warning of seepage or piping processes, thereby helping to prevent breach formation and enhance flood risk management (Dezert et al., 2019).

This work describes the results of an experimental monitoring system developed on an earthen levee along the Tatarena stream, central Italy.  In particular, the outcomes of an ERT monitoring system is used to collect geophysical parameters (i.e. electrical conductivity and permittivity) correlated to the main hydraulic characteristics of the investigated soil (levee body and foundation), such as porosity, water content, permeability. The observations are correlated with rainfall and groundwater measurements and used as a reference data to address numerical modelling of water infiltration process for seepage vulnerability assessment. The developed methodology, based on coupling experimental ERT monitoring and numerical modelling, can provide valuable insights into water infiltration processes, enabling the assessment of the hydraulic condition of levees, which is essential for identifying potential critical areas.

Castellarin, A., Di Baldassare, G., Brath. (2011). A floodplain management strategy for flood attenuation in the River Po. River Res. Appl. 27 (8), 1037–1047.

Dezert, T., Palma Lopes, S., Fargier, Y., Côte, P. (2019). Combination of geophysical and geotechnical data using belief functions: Assessment with numerical and laboratory data. Journal of Applied Geophysics, Vol. 170. https://doi.org/10.1016/j.jappgeo.2019.103824.

Palladino M.R., Barbetta S., Camici S., Claps P., Moramarco T. (2019). Impact of animal burrows on earthen levee body vulnerability to seepage, J Flood Risk Management.2020;13 (Suppl. 1): e12559, https://doi.org/10.1111/jfr3.12559.