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Title: Updating soil surface conditions during wind erosion events using the Wind Erosion Prediction System (WEPS)

Author
item Hagen, Lawrence

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2007
Publication Date: 12/1/2007
Citation: Hagen, L.J. 2007. Updating soil surface conditions during wind erosion events using the Wind Erosion Prediction System (WEPS). Transactions of the ASABE. 51(1):129-137. Available: http://asae.frymulti.com/techpapers.asp?confid=min2007

Interpretive Summary: Abstract only.

Technical Abstract: During significant wind erosion events the soil surface is continually modified. However, erosion models rarely account for these changes. The objective of this work is to demonstrate that physically-based field-scale models can improve their accuracy by periodically updating soil surface conditions within an erosion event. During events, the soil surface can become armored. This represents a supply-limited condition and is typical of the upwind portions of a field. Conversely, when additional mobile soil is created or uncovered faster than it is removed, the surface becomes more erodible. The latter condition often occurs on the downwind portions of a field. In this case, soil removal during the storm may be limited by the duration of the erosive winds. To facilitate surface updating in WEPS, a mass balance of the available mobile soil in maintained in two pools - one for the mobile soil on the crust and another for the mobile soil among the immobile aggregates. The net emission of the mobile aggregates is simulated in grid cells along the wind direction and the pools in each cell are updated on a subhourly basis. Partial depletion of a pool may cause cessation of erosion at a given wind speed, but permit erosion to resume at succeeding higher wind speeds. Thus, different sequences of storm wind speeds may interact with surface updating to change total soil loss for a given storm. During an event, random roughness, oriented roughness, and the fraction of mobile aggregate cover are also updated. Overall, surface updating increased WEPS accuracy by distinguishing between soil surfaces that limited supply of mobile aggregates from those that limited erosion only by the duration of the erosive wind speeds.