The Farmland Soil Erosion And Dust Emission Of Bashang,Hebei Province

Bashang of Hebei Province, belonging to the Agro-pastoral ecotone，people still usetraditional farming methods to cultivate there， the wind erosion and desertificationinfluence is strong。The regional farmland is distributed by dry large plots widely，which isa ideal place to conduct field experiment. Based on this, this thesis selects the typicalarea—KangBao County in Hebei Province, using the basic theory and methods of sandphysics, by the way of field observation and wind-tunnel simulation, does a series ofresearches on the soil erosion characterics, soil erosion amount，dust emitting amount and itsinfluence on dustfall, gains some meaningful results as the followings.（1） The surface aerodynamic roughness and farmland crop stubble high ridge are closelyrelated. The rougher the surface is, the stronger the ability of anti-wind erosion is. Thusincreasing the stubble height, paying attention to the angle between DeLong and prevailingwind direction can effectively increase the surface roughness and reduce the wind erosion.Testing on the different kinds of farmland soil with the soil water content scope between0³0cm, it consequences that the water content of stubble-field>that of turn leave of croptillage work at the ground> that of not turn tillage work at the ground. The cohesive strengthof farmland soil particles in high water content is the highest, which does not cause winderosion so easily.The vertical height alternation of the farmland surface sand flow structure along with theprevailing wind direction is based on the exponential function rule. The sand flow structure inthe surface closing to the ground is influenced by the stubble and micro topography and thenturns up to heteromorphosis, which enlarges along with the prevailing wind direction andverges to stable. The bed-load caliber of grinding harrow tillage、 stubble ground changeswith sand collection height in an exponential function rule: Q=aebH（O means bed-load caliberg/h, H means sand collection height cm, a\b means content）. The exponential functioncorrelation coefficient of the three kinds of farmland is above0.76. The bed-load caliber andsand collection height relates to each other closely.The grain size of sand flow wind erosion content is priority to>0.01mm, the content are basically more than80%. Take vertical wind over the cultivated land and leave of crop landwind erosion things changes in particle size0.1mm as a boundary, it changes in a linear rulein60cm high surface within0.25⁰.1mm size in the vertical height.（2） The wind erosion classification strength of KangBao farmland is mild. In all the kindsof farmlands, autumn ground tillage wind erosion modulus is maximum, with average of17.68t·hm^-2, while the leave wind erosion modulus stubble is6.824t·hm^-2. According to thefarmland to release the dust modulus equations indicates: D≥20μm components of the averagedust release modulus3.802t·hm^-2，20μm≥D＞15μm component release0.452average dustmodulus0.452t·hm^-2；15μm≥D＞10μm component release in0.412t·hm^-2；; FarmlandD≤10μmcomponents of the average dust release modulus0.958t·hm^-2.According to the interpretation of wind erosion modulus and dust, calculation of the idealmode KangBao release of all dust, to obtain the result shows that the wind erosion amountand Buddhism dust capacity of leave chi is minimum; when carrying on farmlandproportionment, the bigger proportion the stubble-field is, the smaller the dust emission is.（3） By controlling the layout of farmland, the surface mantle, cultivation measures andreturning cultivated land to forestry, to reduce KangBao farmland to release the dust capacityabove65%, effectively improve the quality of the atmospheric environment, optimized designthe wind erosion control project for farms and improve the regional environmental quality.