A modified resultant drift potential for more accurate prediction of sand transportation in the vicinity of the Keeler Dunes, California

Abstract

The Keeler Dunes Complex is an active dune field located on the northwest corner of Owens (dry) Lake, California. Previous studies (Lancaster and McCarley-Holder, 2013) implicated the exposed surface of the Owens River Delta as the source of sediment for the Keeler Dunes based on the calculation of the Resultant Drift Potential (RDP). Measurements from sand flux monitoring stations located between the Owens River Delta and Keeler Dunes were used to determine the accuracy of using RDP for estimating actual sand transportation. It was found that the net average direction of sand transportation in this area (133°) was not accurately predicted by RDP (97°). Therefore, prior conclusions based on RDP erroneously attributed sediment from the Owens River Delta as a source for the Keeler Dunes. Since RDP calculations are widely used and a convenient method for determining the direction and magnitude of net sand transportation based on meteorological measurements, methods for modifying the RDP to achieve better agreement with sand flux measurements are desirable. Two modifications were found to improve the agreement between calculated RDP and measured sand transportation: 1) accounting for temporal variability in sediment availability (RDP = 130°), and 2) utilization of an area-specific threshold friction velocity (RDP = 129°). Combining these two modifications also resulted in good agreement (RDP = 137°) with the measured sand transportation but did not improve agreement further. These findings suggest that information about surface characteristics (sediment availability and surface roughness) are important to consider when estimating sand transportation based on wind energy.