Single pile: represents a pile made of erosive construction materials at 6 m in diameter.
Linear piles: soil piles usually from excvavtor, along road, channel, or pipeline construction. Consider wind directional effect.
Group piles: spoil, usually from dumper.

For these unlevel surface that out of current SWEEP's scope, adjusting factors Based on the CFD re-calculating analysis to the US-EPA's AP 42 estimation equation can be applied to combine the result with other model (see attached picture). 

For a single-event wind erosion process, factor can be chose according to the dominant speed. If wind speed fluctuated greatly, the total factors (weighted average for all wind speed and directional conditions) are suggested.