Levees

Levees & River Embankment Assessment

Levees are an important component of the national infrastructure, acting in many cases as a transport mechanism for our waterways and also as a crucial safety element protecting urban environments from the threat of flooding. Recent large-scale weather events have led to significant failures in levee systems, highlighting the need for increased evaluation and in some instances continual monitoring of levees and embankments. Issues related to overtopping, erosion, or improper construction can go unnoticed until it is too late, thereby elevating the importance of the right characterization methods that can help to mitigate risks of a levee breach.

 

Levees are an important component of the national infrastructure and there is an increased need for focused, effective characterization technologies including geophysics.

 

In this image an HGI field scientist acquires electrical resistivity data on the crest of a levee to locate conductive targets that may indicate seepage through the structure – hydrogeophysics Inc
 

Geophysical mapping and characterization services offered by HGI can provide the information needed to evaluate and assess the integrity of a levee or embankment. Our methods are tested and trusted and can be deployed in a safe, cost-effective, and non-invasive manner. There are several methods that are well suited for mapping levees, depending on the scale of the survey, detail required, and engineering property desired. Whatever the need, HGI can devise a characterization plan that fits within existing projects for seamless integration.

 

Of the geophysical methods available, typically those that measure the electrical structure or seismic wave velocity of the levee or embankment are most appropriate. In some ways, the electrical structure can be tied directly to soil structure to define cohesive and non-cohesive soil matrix comprising the levee or embankment. Non-cohesive soils can act as a point of erosional failure during flooding and it is important to locate these areas before a catastrophic event occurs. The example below shows a long stretch of resistivity acquired along an old levee that was built with material at hand. Higher resistivity data in red correlated to sandy materials, which spanned a length of almost 600ft. While the DC electrical resistivity method was used to acquire this detailed dataset, there are other means to obtain electrical resistivity sections of these structures, e.g., electromagnetic methods or capacitively coupled resistivity which can be transported behind a vehicle for continuous coverage along the levee length. Similarly with the seismic methods, and each method has its strengths and price points.

 

HGI’s use of geophysical methods for characterizing levees or embankments focuses on appropriate engineering parameters important for failure assessment.

Resistivity acquisition along the crest of a levee, highlighting coarse and fine grained textured soils