准噶尔盆地东部土壤风蚀敏感性分级及其区划研究

选取影响准东地区土壤风蚀的4个敏感性因子(风场强度、植被覆盖度、地形起伏度、土壤干燥度),结合GIS空间分析技术,将4个因子的敏感性划分为极敏感、高度敏感、中度敏感、低度敏感和不敏感5个等级,利用层次分析法(AHP)确定敏感性因子权重,最后确定准东地区土壤风蚀综合敏感性分级及其分布规律,并对准东地区进行区划研究。结果表明:准东地区土壤风蚀敏感性在空间分布上存在显著差异,总体呈现为北高南低,西高东低的分布态势;极敏感区、高度敏感区、中度敏感区、低度敏感区和不敏感区分别占准东地区总面积的15.27%、17.20%、22.66%、19.49%和25.38%。通过对准东地区土壤风蚀敏感性分级研究,并提出其分区保护与建设措施,以期为准东地区经济发展与环境保护提供科学参考。     

Impact factors of soil wind erosion in the center of Taklimakan Desert

The development and progress of soil wind erosion are influenced by the factors of climate,terrain,soil and vegetation,etc. This paper,taking Tazhong region,a town in the centre of the Taklimakan Desert,as an example and using comparative and quantitative methods,discussed the effects of climate,surface roughness(including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3,while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region,the surface roughness height is relatively small with a mean of 6.32 × 10-5 m,which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types,soil particle size,lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate,vegetation and surface soil properties.     

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion. In this study, three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region, China and placed in a wind tunnel where they were subjected to six different wind speeds (10, 15, 17, 20, 25, and 30 m/s) to simulate wind erosion in the wind tunnel. After each test, the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model (DEM), and the changes in wind erosion mass and microtopography were quantified. Based on this, we performed further analysis of wind erosion-controlling factors. The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23% for the three undisturbed soil samples. With increasing wind speed, the microtopography on the undisturbed soil surface first became smooth, and then fine stripes and pits gradually developed. In the initial stage of wind erosion processes, the ability of the soil to resist wind erosion was mainly affected by the soil hardness. In the late stage of wind erosion processes, the degree of soil erosion was mainly affected by soil organic matter and CaCO₃ content. The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.     

农田耕作方式与土壤风蚀强度关系的风洞模拟实验

以土壤风蚀严重的河北坝上康保县为研究区,采用风洞试验的技术手段,对农田耕作方式与土壤风蚀强度的关系进行研究。结果表明,农田留茬与翻耕、农田垄向及农作物残茬高度的差异对土壤风蚀强度有较大影响。垄向平行主风向的风蚀强度大于垄向垂直主风向的风蚀强度。风速越大,垄向不同造成的风蚀强度的差异越大,尤其是当风速≥15m/s时,风蚀强度的差异表现得较为明显;风蚀强度与留茬高度呈负相关;翻耕地的风蚀强度大于任何留茬地的风蚀强度;风蚀强度与风速变化呈现出指数函数变化规律。因此,农田垄向垂直主风向、作物收获后不进行翻耕、留有适度茬高、优先种植残茬硬度较大的莜麦作物,这样的耕作方式可有效降低土壤风蚀强度,缓解河北坝上地区农田土壤风蚀状况。     

灌木林优化配置格局对土壤风蚀的影响

低覆盖度时,灌木林的水平配置格局成为制约土壤风蚀的重要因素。以宁夏盐池县风沙区人工灌木林基地为试验区,研究了不同下垫面类型和不同配置格局的灌木沙障对风速、近地表输沙率和地表粗糙度的影响。结果表明:灌木林的防治土壤风蚀能力与灌木林的种类、高度和配置格局有直接关系:行带式配置能显著提高灌木林的防风效果,其中以沙柳林效果最佳;三行一带、平均高1.5m、行距1.5m、插深0.5m配置规格的沙柳沙障对地表土壤风蚀的控制效果最好,但防护范围限15倍带高以内;在行数一定的情况下,沙障高度越低,控制土壤风蚀能力越强。     

干涸湖床不同类型盐土地表净风吹蚀实验研究

以内蒙古东乌珠穆沁旗及浑善达克沙地区域干涸湖床3种不同形态的盐土原状土为对象,通过风洞模拟实验,研究了干涸湖床不同类型盐土地表的净风吹蚀速率。对比风洞实验测定结果发现,3种盐土净风吹蚀速率依次是:蓬松盐霜盐土(14.44 g·m^-2·min^-1)>普通盐土(1.00 g·m^-2·min^-1)>结皮盐土(0.42 g·m^-2·min^-1)。风蚀过程中,不同类型盐土的近地表物质输移主要集中分布在0~10 cm的高度范围内,初始运动中,实验盐土风蚀颗粒物质以就地滚动和近距离跃移为主。实验观测发现,随着风速的增大,更多、更大的表面物质会受到更强烈的撞击与磨蚀作用,形成较细小的粉尘物质释放于空中,因此,干旱区盐土地表是形成区域盐碱浮尘或含盐沙尘天气的重要物源。不同类型盐土近地表物质输移总量从大到小依次是:蓬松盐霜盐土(3.17 g)、结皮盐土(0.42 g)、普通盐土(0.35 g)。     

Interactive effects of wind speed,vegetation coverage and soil moisture in controlling wind erosion in a temperate desert steppe,Inner Mongolia of China

The rapid desertification of grasslands in Inner Mongolia of China poses a significant ecological threaten to northern China. The combined effects of anthropogenic disturbances(e.g., overgrazing) and biophysical processes(e.g., soil erosion) have led to vegetation degradation and the consequent acceleration of regional desertification. Thus, mitigating the accelerated wind erosion, a cause and effect of grassland desertification, is critical for the sustainable management of grasslands. Here, a combination of mobile wind tunnel experiments and wind erosion model was used to explore the effects of different levels of vegetation coverage, soil moisture and wind speed on wind erosion at different positions of a slope inside an enclosed desert steppe in the Xilamuren grassland of Inner Mongolia. The results indicated a significant spatial difference in wind erosion intensities depending on the vegetation coverage, with a strong decreasing trend from the top to the base of the slope. Increasing vegetation coverage resulted in a rapid decrease in wind erosion as explained by a power function correlation. Vegetation coverage was found to be a dominant control on wind erosion by increasing the surface roughness and by lowering the threshold wind velocity for erosion. The critical vegetation coverage required for effectively controlling wind erosion was found to be higher than 60%. Further, the wind erosion rates were negatively correlated with surface soil moisture and the mass flux in aeolian sand transport increased with increasing wind speed. We developed a mathematical model of wind erosion based on the results of an orthogonal array design. The results from the model simulation indicated that the standardized regression coefficients of the main effects of the three factors(vegetation coverage, soil moisture and wind speed) on the mass flux in aeolian sand transport were in the following order: wind speedvegetation coveragesoil moisture. These three factors had different levels of interactive effects on the mass flux in aeolian sand transport. Our results will improve the understanding of the interactive effects of wind speed, vegetation coverage and soil moisture in controlling wind erosion in desert steppes, and will be helpful for the design of desertification control programs in future.     

Computational fluid dynamics evaluation of the effect of different city designs on the wind environment of a downwind natural heritage site

Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a site.This study conducted 3D computational fluid dynamics(CFD)simulations to evaluate the effect of a proposed city design on the wind environment of the Crescent Spring,a downwind natural heritage site located in Dunhuang,Northwestern China.Satellite terrain data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)Digital Elevation Model(DEM)were used to construct the solid surface model.Steady-state Reynolds Averaged Navier-Stokes equations(RANS)with shear stress transport(SST)k-ωturbulence model were then applied to solve the flow field problems.Land-use changes were modeled implicitly by dividing the underlying surface into different areas and by applying corresponding aerodynamic roughness lengths.Simulations were performed by using cases with different city areas and building heights.Results show that the selected model could capture the surface roughness changes and could adjust wind profile over a large area.Wind profiles varied over the greenfield to the north and over the Gobi land to the east of the spring.Therefore,different wind speed reduction effects were observed from various city construction scenarios.The current city design would lead to about 2 m/s of wind speed reduction at the downwind city edge and about 1 m/s of wind speed reduction at the north of the spring at 35-m height.Reducing the city height in the north greenfield area could efficiently eliminate the negative effects of wind spee.By contrast,restricting the city area worked better in the eastern Gobi area compared with other parts of the study area.Wind speed reduction in areas near the spring could be limited to 0.1 m/s by combining these two abatement strategies.The CFD method could be applied to simulate the wind environment affected by other land-use changes over a large terrain.     

浑善达克沙地南缘风蚀量的研究

在对浑善达克沙地南缘多伦县沙漠化土地调查中,就其风蚀地貌进行了详细的研究,不仅论证了风蚀地貌的形成、类型和分布,而且实测了不同类型区的风蚀量数据。并采用克拉瓦洛维克的风蚀强度公式计算了该地区风蚀量的理论值。以测定数据为基础,研讨了增加地表粗糙度的方法及防止或减缓风蚀的有效途径,并且具有在同类地区示范推广作用。     

土壤风蚀量随风速的变化规律研究

使用野外风洞作为风蚀研究的试验手段,通过农田土壤、沙及生土的风洞试验研究发现,农田土壤的风蚀量随风速呈指数函数变化,沙及生土的风蚀量随风速呈幂函数变化。试验研究还表明,农田土壤的风蚀量与表土层(3cm)的含水量呈显著负相关,沙的风蚀量与含水量的相关性不显著。风蚀导致土壤中的细颗粒成分大量损失,这是土壤颗粒粗化的原因所在。     

An experimental study on the influences of wind erosion on water erosion

In semi-arid regions, complex erosion resulted from a combination of wind and water actions has led to a massive soil loss and a comprehensive understanding of its mechanism is the first step toward prevention of the erosion. However, the mutual influences between wind erosion and water erosion have not been fully understood. This research used a wind tunnel and two rainfall simulators and simulated two rounds of alternations between wind erosion and water erosion(i.e., 1~(st) wind erosion–1~(st) water erosion and 2~(nd) wind erosion–2~(nd) water erosion) on three slopes(5°, 10°, and 15°) with six wind speeds(0, 9, 11, 13, 15, and 20 m/s) and five rainfall intensities(0, 30, 45, 60, and 75 mm/h). The objective was to analyze the influences of wind erosion on succeeding water erosion. Results showed that the effects of wind erosion on water erosion were not the same in the two rounds of tests. In the 1~(st) round of tests, wind erosion first restrained and then intensified water erosion mostly because the blocking effect of wind-sculpted micro-topography on surface flow was weakened with the increase in slope. In the 2~(nd) round of tests, wind erosion intensified water erosion on beds with no rills at gentle slopes and low rainfall intensities or with large-size rills at steep slopes and high rainfall intensities. Wind erosion restrained water erosion on beds with small rills at moderate slopes and moderate rainfall intensities. The effects were mainly related to the fine grain layer, rills and slope of the original bed in the 2~(nd) round of tests. The findings can deepen our understanding of complex erosion resulted from a combination of wind and water actions and provide scientific references to regional soil and water conservation.     

耕作地表土块状况及其对近地表风场的影响

为深入理解非可蚀性土块吸收风能、降低侵蚀力的机制,利用野外风速资料,对半干旱区农田传统耕作模式下犁耕、耙耱及抹平等的地表土块大小、土壤表面粗糙度、近地表风速及空气动力学特征进行了研究。结果表明,犁耕后农田土块长、宽、高均在15 cm以上,盖度为27.67%,耙耱、抹平后土块大小和盖度显著降低,抹平地表土块盖度仅为2.13%;土块的破碎导致土壤表面粗糙度降低,近地表风速增大;与犁耕地表比较,耙耱后土壤表面粗糙度降低34%~64%,抹平后降低幅度甚至在90%以上;耙耱抹平后地表以上0.5 m高度内风速显著增大,空气动力学粗糙度由1.1 cm降低至0.05 cm,侵蚀力增强。因此认为,合理选择犁耕、耙耱和抹平的时间对农田风蚀防治有实际意义。     

作物残茬覆盖对农田土壤风蚀的影响

为定量评价干旱半干旱地区农田土壤抗风蚀效果,采用移动式风洞及其配套测试系统对内蒙古武川县上秃亥乡农田地表进行了原位测试研究。结果表明,不同风速下土壤风蚀量随作物残茬盖度的增加呈指数规律减少;40%以上残茬盖度可明显提高土壤颗粒起动风速并减少风蚀量;当风速为14~18 m/s时,地表作物残茬盖度为60%~80%具有较好的抗风蚀效果。     

A field investigation of wind erosion in the farming–pastoral ecotone of northern China using a portable wind tunnel: a case study in Yanchi County

The farming–pastoral ecotone in northern China is an extremely fragile ecological zone where wind erosion of cropland and rangeland is easy to occur. In this study, using a portable wind tunnel as a wind simulator, we conducted field simulated wind erosion experiments combined with laboratory analysis to investigate wind erosion of soils in trampled rangeland, non-tilled cropland and tilled cropland in Yanchi County, China. The results showed that compared with rangeland, the cropland had a higher soil water holding capacity and lower soil bulk density. The wind erosion rate of trampled rangeland was much higher than those of non-tilled cropland and tilled cropland. For cropland, the wind erosion rate of the soil after tilling was surprisingly less than that of the soil before tilling. With increasing of wind speed, the volume mean diameter of the eroded sediment collected by the trough in the wind tunnel generally increased while the clay and silt content decreased for all soils. The temporal variation in wind erosion of the trampled rangeland indicated that particle entrainment and dust emission decreased exponentially with erosion time through the successive wind erosion events due to the exhaustion of erodible particles.     

北京平原土壤机械组成和抗风蚀能力的分析

土壤遇风起沙是风沙活动产生的最根本原因,它的基本点有二:一是具有足以使砂粒产生运动的一定强度的起沙风;二是土壤颗粒小、质地干燥疏松,具有遇风起沙产生运动的属性。本文分析了北京土壤的机械组成特征和结构性能等。叙述了在永定河边部一些地块的野外风沙观测和沙风洞试验,证实土壤结构性、干松程度、植被覆盖状况是决定土壤抗风蚀性能的三要素。最后,试用不易蚀因子含量评价北京平原土壤的抗风蚀能力。     

沙漠-黄土过渡带风水复合侵蚀营力特征——以靖边县为例

以北京师范大学陕西省靖边县榆林风沙科学野外实验站自动气象站2007-2009年的降雨、风速和风向数据为基础,分析沙漠-黄土过渡带风水复合侵蚀营力的特征。结果表明：① 研究区年内降雨量≥12 mm的降雨事件主要分布在5-9月,月平均降雨侵蚀力8月最大,为318.24 MJ·mm/(hm²·h·a),年平均降雨侵蚀力为510.08 MJ·mm/(hm²·h·a);② 该区西北风占主导地位,东南风次之,累计频率分别为43.8%和16.21%;起沙风主要集中在3-6月,其频率分别为19.34%、12.34%、20.5%、12.39%;③ 研究区年平均输沙势（DP）、合成输沙势（RDP）分别为228.76 VU、41.73 VU,合成输沙方向（RDD）为141.17°,方向变率指数（RDP/DP）为0.2,起沙风变率较大,属于中等风能环境,沙物质向东南偏南方向输移。     

Assessing the effects of vegetation and precipitation on soil erosion in the Three-River Headwaters Region of the Qinghai-Tibet Plateau,China

Soil erosion in the Three-River Headwaters Region (TRHR) of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological environment. Vegetation and precipitation are considered to be the main factors for the variation in soil erosion. However, it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel scale. To assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015, we employed the Revised Universal Soil Loss Equation (RUSLE) model to evaluate soil erosion in the TRHR, and then developed a method using the Logarithmic Mean Divisia Index model (LMDI) which can exponentially decompose the influencing factors, to calculate the contribution values of the vegetation cover factor (C factor) and the rainfall erosivity factor (R factor) to the variation of soil erosion from the pixel scale. In general, soil erosion in the TRHR was alleviated from 2005 to 2015, of which about 54.95% of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor, and 41.31% was caused by the change in the R factor. There were relatively few areas with increased soil erosion modulus, of which 64.10% of the area where soil erosion increased was caused by the change in the C factor, and 23.88% was caused by the combined effects of the C factor and the R factor. Therefore, the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion, while the C factor was the dominant factor for the increase of soil erosion. The area with decreased soil erosion caused by the C factor (12.10×10³ km²) was larger than the area with increased soil erosion caused by the C factor (8.30×10³ km²), which indicated that vegetation had a positive effect on soil erosion. This study generally put forward a new method for quantitative assessment of the impacts of the influencing factors on soil erosion, and also provided a scientific basis for the regional control of soil erosion.     

土壤风蚀对表层土壤粒度特征的影响

土壤风蚀是一种严重的环境问题。文中选择我国西北干旱及半干旱区,风蚀严重的盐池县风沙土地为研究对象,利用Marven2000粒度分析仪对不同风蚀强度的表层土壤粒度进行分析,探讨土壤风蚀过程对地表粒度的影响,研究表明:随着风蚀程度的增加,表层土壤粒度逐渐变粗,由灌丛-推平耕地-草地-吹蚀地,地表中的细沙,粉沙和粘土的含量逐渐降低,而中沙和粗沙的含量逐渐增加。灌丛表面以细沙为主,占34.9%;推平耕地和草地以中沙为主,占32.7和39.1%;吹蚀地以粗沙为主,占44.2%;土壤平均粒径逐渐变粗,分别为2.48,2.08,1.91,1.12φ。土壤风蚀过程,地表的细沙,粉沙和粘土大量损失,灌丛的细沙,粉沙和粘土分别占34.86,20.01和10.98%,但在严重风蚀的吹蚀地,细沙,粉沙和粘土仅占6.09,3.72和2.52%。由此可见,土壤风蚀造成地表细颗粒物质损失,形成沙漠化土地。不同地表沙粒的分维数不同,随平均粒径增加,分维数总体降低。     

河北坝上风蚀对农田土壤肥力水平影响研究

河北坝上地区风多风大,冬春季节降水少,使得大片农田长期处于强烈的风蚀之中.由于地表土壤养分的大量流失,农田土壤生产能力下降,导致荒漠化进程加剧.针对传统和保护性耕作农田土壤及风蚀物养分的变化,研究分析了土壤的风蚀和有机物及养分衰减的定量关系及其衰减的机理.结果表明:风蚀过程是农田土壤退化的重要路径,可以通过风蚀物中有机质和养分的含量估算农田土壤的有机质和养分的损失量.土壤风蚀过程中,保护性耕作比传统耕作可以减少风蚀量62.56%.有机质损失减少31.05%,全氮损失减少29.15%,全磷损失减少32.25%,全钾损失减少66.11%;有机质及养分主要集中在细微的土壤颗粒之中.风蚀对土壤营养物质及有机质的流失高于土壤的流失,风蚀是土壤退化的重要原因,恶化环境的同时造成了严重的经济损失.可以采用保护性耕作技术防止农田沙漠化和提高作物产量.     

An experimental study on the influences of water erosion on wind erosion in arid and semi-arid regions

Complex erosion by wind and water causes serious harm in arid and semi-arid regions. The interaction mechanisms between water erosion and wind erosion is the key to further our understanding of the complex erosion. Therefore, in-depth understandings of the influences of water erosion on wind erosion is needed. This research used a wind tunnel and two rainfall simulators to investigate the influences of water erosion on succeeding wind erosion. The wind erosion measurements before and after water erosion were run on semi-fixed aeolian sandy soil configured with three slopes(5°, 10° and 15°), six wind speeds(0, 9, 11, 13, 15 and 20 m/s), and five rainfall intensities(0, 30, 45, 60 and 75 mm/h). Results showed that water erosion generally restrained the succeeding wind erosion. At a same slope, the restraining effects decreased as rainfall intensity increased, which decreased from 70.63% to 50.20% with rainfall intensity increased from 30 to 75 mm/h. Rills shaped by water erosion could weaken the restraining effects at wind speed exceeding 15 m/s mainly by cutting through the fine grain layer, exposing the sand layer prone to wind erosion to airflow. In addition, the restraining effects varied greatly among different soil types. The restraining effects of rainfall on the succeeding wind erosion depend on the formation of a coarsening layer with a crust and a compact fine grain layer after rainfall. The findings can deepen the understanding of the complex erosion and provide scientific basis for regional soil and water conservation in arid and semi-arid regions.