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 an d 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 we re built and characterized as either high or low density. The swash wa s modeled as a bore which was generated using a head tank. The data co nsisted of bore height, bore velocity, specific volume eroded and dune density for ninety-seven individual tests. These data were analyzed u sing Maximum Likelihood Estimation (MLE) and Likelihood Ratio (LR) tes t methods. The conclusions are (1) swash force and dune erosion are re lated linearly, (2) decreasing the sand grain size of the dune decreas es the amount of dune erosion for the same swash force, and (3) increa sing dune density decreases the amount of dune erosion for the same sw ash force. In addition, for these test data, the difference in sand gr ain size influences the amount of dune erosion for a given swash force more than that due to the increase in dune density.