|其他摘要||The Aksu region within the Tarim Basin is a major source of windblown dust in China due to the arid climate and vast areas under intensive irrigated crop production. This present study focus on the soil wind erosion of Tarim Basin.The objectivity of this study was to investigate wind erosion process and aerodynamic properties of three typical underlying surfaces (Cotton, Orchard and Oasis – desert transition zone) by outdoor experiment and lab analysis. The soil aggregate was measured, and the creep, potential saltation and suspension were estimated. The results as followed:
(1)The calculated potential soil loss by chandler (1941) and Chepil (2005) equations were followed: Transition> cotton >orchard, and it was consistent with measured results. The aerodynamic properties was measured, the results showed that Transition zone had lowest friction velocity, zero plane displacement and aerodynamic roughness, and Orchard had highest lowest friction velocity, zero plane displacement and aerodynamic roughness, indicated that Transition zone had highest potential wind erosion. Therefore, mitigation of soil winderosion and fine-particle emission should be considered inTransition zone.
2)The high wind events was concentrated in April and May in study region. The number and intensity of high wind events of transition zone more than the other treatments. The high wind events were concentrated in three wind direction of SEE, E and NWW from Transition zone, and was concentrated in N, NE, NNE and ENE in cotton and orchard.
(3)The only 10% sand horizontal flux data was fit the power function from cotton and orchard by BSNE collected. While the all horizontal flux data was fit the power function from Transition zone. The amount of soil loss of Transition zone more than other treatments, indicated that the field operation and vegetation has great effect on the soil wind erosion. Transition zone has highest potential suspension, particular in a diameter less than 50um that could have long transportation. Transition zone not only was dust source for dust storm, but also could have long transportation and have effect on air quality for other place. The potential creep was little in three treatments, indicated that the creep was not a main wind erosion form.
(4)The structure of sediment flux, the saltation activity characteristics observed by Sensit and the aggregated particle size distribution of sediment trapped by BSNE together showed that the main dust emission mechanism was not depend on saltation, but mainly depend on the aerodynamic. DPM modelwas used to simulate dust emissionin ot the study area, and saltation fluxes of simulated values and measured values were consistent, however, for sediment emission flux (sediment vertical flux) , the simulation values were far lower than the measured values.
(5)Analyzed the physical mechanism DPM model and combined with parts of conclusions of this study, then find out the reasons of errors occurring between the simulated values and measured values in using DPM mode to simulate the study area’s dust emission. Based on the previous work, deduced a expression of dust emission which caused by aerodynamic and improved the DPM model.|