Validation of SWEEP for Contrasting Agricultural Land Use Types in the Tarim Basin

The Tarim Basin is amajor source of windblown dust in China. Land management and use can greatly impact windblown dust, thus, models such as the Wind Erosion Prediction System (WEPS) are important for identifying management practices that reduce the emission of dust. The objective of this study was to test the performance of the WEPS erosion submodel (the Single-event Wind Erosion Evaluation Program (SWEEP)) under contrasting agricultural land use types in the Tarim Basin of northwest China. Wind erosion of a sandy soil was measured and simulated in a cotton (Gossypium hirsutum L.) field and red date (Ziziphus jujuba L.) orchard during the spring of 2012 and 2013. The SWEEP did not simulate differences in soil loss for contrasting agricultural land use types, although measured soil loss was typically smaller than that considered to be of consequence (> 100 g m(-2)) in the original design of the SWEEP. In fact, the model simulated no erosion for all six high wind events in which we observed erosion in the cotton field and red date orchard. The insensitivity of SWEEP to simulate erosion was caused by the simulated friction velocity being consistently lower than the threshold friction velocity for the loess soil at the cotton field and red date orchard. Because SWEEP is being used to assess wind erodibility of lands and simulate regional air quality in China, SWEEP must be improved for application to lands that emit large and small amounts of windblown dust.