Study On The Soil Loss Estimation By Wind Erosion At Field Scale

Field is the basic unit of soil wind erosion calculation,and its topography,soil texture,vegetation and land use conditions are usually regarded as the same,but with the change of field scale(ranging from several square meters to several square kilometers),the wind erosion process and the corresponding wind erosion amount will also change.Therefore,how to estimate the amount of wind erosion under different field scales is the difficulty and focus of current wind erosion research.In this paper,the typical farmland in kangbao county,Bashang area,Hebei Province is taken as the research area,and the random wind erosion observation network scheme recommended by the US Department of Agriculture(the plot size is 100m×100m)is adopted.Through field experiment observation,the vertical and along-the-way changes of wind-blown sand flow structure at field scale and the changes of wind erosion characteristics at different field scales are analyzed,and the influence of different field scales on soil wind erosion calculation is analyzed.The main results are as follows:(1)Based on the data of three typical wind erosion events,the observed data of three wind erosion events are compared with six kinds of sediment transport flux equations,namely Stout&Zobeck,Shao&Raupach,Namikas,Ni,Panebianco and power function,and integrated and fitted.(2)Comparing the fitting results of six wind path effect models,namely Stout(1990),Andreotti,Fryrear,Visser,Logistic and Zhang Chunlai,to the wind erosion event data.The analysis shows that Logistic model has a good simulation effect on farmland wind effect,and the fitting correlation of wind erosion event I and below 0.5m height is more than 0.9.The correlation of all heights of wind erosion event 3 exceeds 0.7;Fryrear model,Stout model,Zhang Chunlai model and Andreotti model have good simulation effects on wind erosion event I,and the fitting correlation below 0.3m height is all over 0.7;However,the simulated Zhang Chunlai model and Andreotti model of wind erosion event III can not be well fitted.Visser model has no good fitting effect on the two wind erosion events.(3)According to the random wind erosion observation network scheme recommended by USDA,the inverse distance weighting method(IDW)is used to interpolate the field scale sediment transport flux.By comparing and analyzing different grid sizes(1m,3m,5m,7m,10m),it is found that the side length of the interpolated grid affects the sediment transport flux and erosion change in the area,and the size of the interpolated grid has no obvious influence on the overall trend change of sediment transport flux in the observation area.However,with the increase of the side length of the interpolation grid,the extreme value gap gradually decreases,and the erosion change is consistent with the sediment flux change law.(4)By calculating the soil wind erosion of the side length of the interpolation grid of 1m,3m,5m,7m and 10 m,it is found that the wind erosion of the observation plot of 100m×100m increases with the increase of the side length of the interpolation grid.By calculating the wind erosion amount of the side length of the observation area of 20 m,30m,50 m,70m and 100 m,it is found that the wind erosion amount of the wind erosion event I and the wind erosion event II(single and short-term wind erosion events)first increases and then decreases with the increase of the observation scale,and the change trend conforms to the quadratic polynomial function.The amount of wind erosion in the third wind erosion event(monthly wind erosion event)decreases with the increase of observation scale,and the changing trend conforms to logarithmic function.