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Wind Erosion:
An International Symposium/Workshop

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Wind Erosion Prediction System: Erosion Submodel

Lawrence J. Hagen


An overview of the tasks of the erosion submodel of the Wind Erosion Prediction System (WEPS) is presented with emphasis on the prediction equations for the saltation/creep and suspension components. These tasks begin with calculation of surface threshold velocities and end with periodic updates in surface conditions caused by the soil loss and deposition that occur during erosion. Wind erosion equations for a uniform surface during quasi-steady conditions were derived, based on the principle of conservation of mass. In the first equation, the major processes involved in saltation/creep creation and transport were simulated. These processes included direct emission of loose material, entrainment of material abraded from exposed clods and crust, breakage of saltation/creep aggregates to suspension-size, trapping of saltation/creep when transport capacity is exceeded on microrelief, and interception by plant stalks. In the second equation, the major processes involved in creation and transport of the suspension component of wind erosion were simulated. These processes included emission of loose material, abrasion from exposed clods and crusts, and breakage of the saltation/creep to form suspension-size aggregates. A downward flux to the surface of coarse fractions of the suspension component also was simulated in portions of the simulation region, where saltating aggregates were not present.