Assessment of Levees Using Field Instrumentation and Geophysical Methods

Levees along the Mississippi River play an important role in ensuring the security of life and property in flooding events. The degree of saturation and moisture content of levees containing high-plastic clay soils can increase their vulnerability to shallow slope failures. The frequent fluctuation of the water levels of the Mississippi River increases the potential of water infiltration which in turn increases the risk of shallow slope problems. Therefore, it is critical to monitor the water level inside the levees to evaluate the effects of the water table elevation on the levee performance. Field instrumentation and Electrical Resistivity Imaging (ERI) are used to investigate the soil subsurface conditions in terms of soil moisture variation, and perched water zones. The objective of the current study is to integrate the data collected from electrical resistivity imaging (ERI) with the change in subsurface water pressure to evaluate the performance of two levee sections on the Mississippi east levee system in Norfolk north of Mississippi. A piezometer was installed at the toe of each levee section to monitor the water table levels. Moreover, a 2D ERI test was conducted along three survey lines at the crest and middle of each levee slope to investigate the soil subsurface conditions in terms of soil moisture variation and perched water zones.