Wind Tunnel Simulation Of Soil Wind Erosion In Stipa Breviflora Desert Steppe

Soil wind erosion is an important factor affecting ambient air quality and human health.The desert steppe in Inner Mongolia is affected by natural factors such as scattered soil particles,low annual rainfall and high evaporation,sparse vegetation and grazing,which lead to wind erosion in spring every year in this region.Soil moisture content,wind speed and vegetation coverage are important factors affecting soil wind erosion,However,its mechanism of action on soil wind erosion needs to be further studied.Therefore,in this paper,undisturbed soil collected from desert steppe Stipa breviflora Griseb in Sunit Right Banner,Xilin Gol League,Inner Mongolia was taken as a case study.Through field investigation and analysis of meteorological data in the study area,the wind speed used in the test was finally determined to be 10,13,17 m/s.The soil moisture content was 1.5%,2.5%,3.5%,and the vegetation coverage was 10%,15%,20%,25%,30%.Wind tunnel simulation tests were carried out on the mechanism of vegetation coverage,soil moisture and wind speed in the process of soil wind erosion,in order to provide scientific and effective theoretical guidance for desert steppe wind erosion areas.The study says:(1)Before and after wind erosion,the volume fraction of soil particles was significantly different under different grazing intensities(P<0.05).The soil particles were mainly sand,and the proportion of silt and clay particles was very small.After wind erosion,the volume fraction of sand increased,and the volume fraction of silt and clay decreased,and the volume fraction of sand and silt showed opposite distribution law in each grazing intensity plot.Before and after wind erosion,soil organic carbon content and total nitrogen content showed the same distribution pattern with grazing intensity(CK>LG>EG>HG>MG),and soil total phosphorus content showed a fluctuating change.On the whole,with the increase of grazing intensity,soil nutrient content decreased,and soil nutrient content decreased with the occurrence of wind erosion.(2)Under the same vegetation coverage,soil threshold wind velocity was significantly different under different soil moisture content treatments(P<0.05).Under the same soil moisture content(except 1.5%,vegetation coverage increased from 10%to 15%),vegetation coverage significantly affected soil threshold wind velocity(P<0.05).Under the conditions of each surface vegetation coverage and the same wind speed,the soil wind erosion rate decreased significantly with the increase of soil moisture content(P<0.05).When the wind speed was low,the soil wind erosion rate was greatly affected by soil moisture content.(3)Under the same vegetation coverage and wind speed,the increase of soil moisture content significantly decreased soil sediment transport(P<0.05).The decreasing rate of sediment transport increased gradually with the increase of vegetation coverage.Under the same vegetation coverage,the accumulation of wind-blown sand quicksand material gradually weakens with the increase of wind speed and the effect of soil moisture content.When the wind speed is low,the accumulation of sediment in the lower layer decreases first and then increases with the increase of vegetation coverage.(4)Soil moisture content and vegetation coverage had extremely significant positive correlation with soil threshold wind velocity(P<0.01),while soil moisture content had extremely significant negative correlation with wind-driven sand flow structure and sediment transport amount(P<0.01),and vegetation coverage had extremely significant negative correlation with wind erosion rate,sediment transport amount and wind-driven sand flow structure(P<0.01).(5)By multiple linear regression analysis,the fitting equation between soil threshold wind velocity and soil moisture content and vegetation coverage was as follows:TV=4.380+0.288M+0.031V,R~2=0.927;Soil wind erosion rate,sediment transport and soil moisture content,vegetation coverage,grazing intensity and wind speed meet the fitting equation,respectively:E=-24.264-1.542M-0.793C+4.139V,R~2=0.720;TS=-25.558-5.945M-1.216C+6.149V,R~2=0.701.The contribution value of soil moisture content to threshold wind velocity was significantly higher than that of vegetation coverage.and the contribution value of wind speed to soil wind erosion rate and sand transport was significantly higher than that of soil moisture content and vegetation coverage.