Numerical Simulation On Soil Wind-blown Erosion From Cropland In Northeastern China

Due to characteristics of climate and cultivation in northern China, the long coldseason is coupled with frequent cold fronts and strong spring wind, which makes theexposed cropland vulnerable to wind erosion from harvest of crops in early October tolate April the following year. The loss of top soil caused by wind-blown erosion notonly reduces soil productivity, but also degrades air quality and contributes to regionalhaze.This study aims to measure and simulate the unique characteristics of black soilcropland wind erosion from farmland in Northeast China. Extensive field observationswere conducted in a farm in Dehui, and a bare land site in Changling to compare thecontrolling factors for wind erosion for different land use and soil types. Theobservational data obtained these field experiments was subsequently used to argumentthe wind-blown emission model (CMAQ-FENGSHA) parameters to simulate theobserved dust events over the cropland in Northeast China. The main factors affectingsoil erosion activities in farmland include wind speed, soil moisture, soil texture, landuse type, surface roughness, swell direction, etc. Wind-blown erosion activity hadpositively correlated with wind speed and negative correlation with soil moisture,vegetation and soil roughness. The threshold wind speed was3m/s at0.5m height andat2m height was7m/s. The threshold wind speed was2m/s at0.5m height and at2mheight was6m/s in Changling region.Wind erosion event of Dehui was simulated by WRF-CMAQ-FENGSHA withlocalizing parameters. Simulation results are good agreement with the measured valuesfrom TEOM Series1400a with a correlation coefficient of0.73during the May31,2013event, as well as the aerosol optical depth obtained from satellite (MODIS aboard Aqua) Our results indicate that the bare farmland areas over northeastern Chinaare important dust sources this region.Compared with the dust storms on April7,2001, dust emissions in2013aresignificantly lower than2001and the highest dust emissions in2013are only23%of2001. The distribution is mainly concentrated dust source area in Inner Mongoliaduring2001, while it is more scattered in cropland area in Liaoning and Jilin during2013. Dust emissions of dust source area in Inner Mongolia is very small, less than0.79g/s. AOD concentration in the central region of Jilin is higher dust source area inInner Mongolia from the image of OMI satellite remote sensing. Based on the aboveanalysis, the simulation results on May31are less affected by dust source area in InnerMongolia, mainly from the impact of agricultural activities in Northeast China.