Laboratory investigation of dune erosion as a function of sand grain size and dune density

The relationship between swash force, sand grain size, dune density and dune erosion was investigated in a series of laboratory experiments. The sands selected for the experiments were a coarse grain sand from North Carolina and a fine grain sand from Oregon. Small scale dunes were built and characterized as either high or low density. The swash was modeled as a bore which was generated using a head tank. The data consisted of bore height, bore velocity, specific volume eroded and dune density for ninety-seven individual tests. These data were analyzed using Maximum Likelihood Estimation (MLE) and Likelihood Ratio (LR) test methods. The conclusions are (1) swash force and dune erosion are related linearly, (2) decreasing the sand grain size of the dune decreases the amount of dune erosion for the same swash force, and (3) increasing dune density decreases the amount of dune erosion for the same swash force. In addition, for these test data, the difference in sand grain size influences the amount of dune erosion for a given swash force more than that due to the increase in dune density.