Computer simulations and physical modelling of erosion

Research is being done to study the details and progress of soil erosion on levees and dams, including the formation and progression of rills and gullies on the slopes, and eventually to final breaching. These detailed observations of erosion differ from the typical predictions of only the maximum erosion or scour depths, for example around submerged bridge piers. Computer simulations and geotechnical centrifuge modelling will, in the future, be validated using these observations. For testing, single layer sand models were utilized, and will be followed by clayey and mixed soils, and increased number of layers. The computer simulations will incorporate 3-D Navier-Stokes fluid simulations, and a novel segmented height field extended to allow soil undercuts was developed. The primary intent of the research is to study small-scale erosion on earthen embankments and, ultimately, develop novel and robust erosion software, validated by physical modelling. Figure 1: A levee that was overtopped for several hours during the Katrina hurricane but did not fail. The dramatic gouging/scooping on the lower portions of the levee is due to increased water flow at the base of the levee and the nonhomogeneous nature of the embankment.