Characterizing Mississippi River Levee Segments Using Soils and Geologic Data
Hasan, K., Aanstoos, J.V., Mahrooghy, M., Dabbiru, L., & Dunbar, J. B. (2011). Characterizing Mississippi River Levee Segments Using Soils and Geologic Data. Proceeding 2011 Symposium on the Application of Geophysics to Environmental and Engineering Problems. Charleston, SC.
Approximately 150 miles of levees in the Lower Mississippi River valley bordering Mississippi, Arkansas and Louisiana are being studied to determine their vulnerability to slough slide failure and sand boil development. The study is designed to use Synthetic Aperture Radar (SAR) imagery from both aerial and satellite platforms as its primary investigative tool. Images have been acquired with NASA’s airborne UAVSAR imaging at L-band and DLR’s satellite borne TerraSAR-X imaging at X-band. Currently multi-faceted analysis of the acquired images is in progress by several of our team members and the results look promising.
To aid the image analysis effort we are also looking at the physical processes of slides and sand boil formation which are highly influenced by subsurface movement of water which in turn is controlled by textural properties of the soil and sediments beneath. To characterize levee segments having unique soil and sediment condition with respect to water transmissivity, soil and geologic data have been collected from NRCS-USDA and USACE respectively. GIS analyses of the textural and geomorphic characteristics of these data have allowed classification of the levee into several zones where water transmission properties may make them more susceptible to failure than other areas. In these zones highly sandy soils on the riverside of levee allows water to move to the levee where clay rich soils restrict lateral flow, creating conditions where the water could move upward to weaken the levee segment. A majority of the known slide events occur in these zones, which supports this inference. The spatial distribution of these slide events also suggests that geomorphic features such as ridge and swale and ox-bow lakes tend to have a geographic association with these events. Vegetation patterns indicative of repaired slides derived from TerraSAR-X images also coincide with these zones based on soil criteria.