An evaluation of the wind erosion module in DUSTRAN

Abstract

Pacific Northwest National Laboratory (PNNL) has developed a dust transport model (DUSTRAN), which calculates atmospheric dust concentrations that result from both natural and human activity. DUSTRAN is a comprehensive dispersion modeling system, consisting of a dust-emissions module, a diagnostic meteorological model, and dispersion models that are integrated seamlessly into graphical information system (GIS) software. DUSTRAN functions as a console application and allows the user to interactively create a release scenario and run the underlying models. We have recently compared dust concentrations calculated by DUSTRAN with observations of wind erosion on the US Department of Energy's Hanford Site in southeastern Washington. In this paper we describe both DUSTRAN's algorithm for predicting the source strength of wind-blown dust and the comparison of simulated dust concentrations with data. The comparisons use observations of PM 10 concentrations for three separate dust events on the Hanford Site in 2001. The dust measurements were made as part of an effort to monitor site recovery following a large range fire that occurred in 2000. The comparisons have provided both encouragement as to the practical value of the wind erosion module in DUSTRAN and examples of occasions when the simulations and observations diverge. In general, the maximum dust concentrations from the simulations and the observations for each dust event agreed closely. Because of the lack of soil moisture information, the model was run in a “dry” mode. However, certain discrepancies between the measured and simulated values relative to the timing of observed precipitation events suggest that soil moisture should be accounted for where possible. For low dust concentrations, DUSTRAN tends to overestimate PM 10 levels. This may be a weakness in the form of the dust flux parameterization at low wind speeds. Overall, however, we have shown DUSTRAN to be an effective tool for simulating dust events due to wind erosion.