Soil Wind Erosion Research Articles

QUANTIFY IMPACT OF WIND EROSION ON ORGANIC MATTER CONTENT UNDER MANAGEMENT PRACTICES, WADI EL RAML, NWCZ, EGYPT

Wind soil erosion is one of the land degradation processes in North Western Coastal Zone (NWCZ) of Egypt. It was assessed under condition of wheat crop grown on a sandy loam soil in Wadi El Raml in 2018/2019. Three tillage treatments of no-tillage (NT), minimum tillage (MT) and conventional tillage (CT) were assessed with or without organic manuring (30 m3 ha-1) combined with or without mulching (with rice straw covering 60% of soil surface).The aim of the study was assessment the impact of wind erosion on wheat yield and soil organic matter content (SOM) under different tillage practices under rainfed agriculture at Wadi El Raml in NWCZ. The highest bulk density was associated with NT. Losses (kg m-2 y-1) of about 275, 221 and 173 were shown in the CT, MT and NT treatments, respectively.The erodibility average values andloss of OM and TN were highest in the bare soil. Soil loss materials for the bare soil was higher than for the cultivated soils, which gave their the highest loss of 275 kg m-2y-1with non-manured non-mulched CT and the lowest of 16 kg m-2y-1for the manured and mulched NT. The highest wheat yield was obtained with manured and mulched CT. The results of this study showed that the use of 30 m3ha-1of organic manure and 60% of the coverage with rice straw in each cultivation type led to improving the soil content of organic matter and reducing soil loss by erosion by wind. This study emphasized the benefits of conservation tillage, such as improving bulk density as a guide to soil quality, which keeps it from degradation, as happens with conventional tillage. The study also recommended the use of conservation tillage in cultivated cereal crops for more than one season under rainfed conditions in Egypt to increase the content of soil organic matter, thus increasing crop productivity compared to the traditional tillage system to achieve sustainable agricultural production inNWCZ of Egypt.

Improved evaluation method of the soil wind erosion intensity based on the cloud–AHP model under the stress of global climate change

Under the stress of global climate change, soil wind erosion has become a major environmental issue in the Three-River Source Region (TRSR) of China. However, few large-scale studies have been conducted on soil wind erosion owing to the lack of investigational data or complex parameters. Moreover, the uncertainty and randomness in the weight determination process cannot be avoided using the traditional method. Thus, a cloud–analytic hierarchy process (cloud–AHP) model was proposed to construct a wind erosion intensity index model for the TRSR based on seven typical land surface parameters. The following results were obtained. (1) The cloud–AHP model can better eliminate the randomness and uncertainty in the weight determination process. (2) The proposed evaluation method of wind erosion intensity has better applicability in the TRSR with overall accuracy of 93%. (3) The overall wind erosion intensity in this region is moderate. The wind erosion intensity was the largest in the Yangtze River (0.55, moderate erosion) and smallest in the source region of the Lancang River (0.50, mild erosion). (4) Significant differences are observed in the influences of various vegetation types on wind erosion intensity. Bare land exhibits the highest wind erosion intensity, whereas a coniferous forest exhibits the smallest. Moreover, grassland is a key control zone of soil and water conservation because it has the largest spatial heterogeneity of internal erosion intensity. These results can provide data and technical support for preventing and controlling soil erosion and protecting the environment in the region.

Soil mechanical properties and wind erosion following conversion of desert to irrigated croplands in central Iran

Conversion of the virgin desert to agricultural lands can obviously alter some soil properties; however, little is known about how this conversion impacts soil mechanical properties and wind erosion. The present study therefore aimed at assessing the impacts of agricultural exploitation on aggregate stability, mechanical properties and wind erosion of desert soils in Abarkooh plain, central Iran. To do so, three land uses were assessed: (1) wheat (Triticum aestivum L.), (2) pistachio (Pistacia vera L.), and (3) the adjacent virgin desert soils. Ten sites including three land uses were selected. At the time of soil sampling, the vane shear test was performed. Then, the composite soil samples (0–20 cm depth) were taken for laboratory analyses. Soil organic carbon, bulk density, mean weight diameter, wind erosion rate, wind erodible fraction, shear strength value, cohesion (c), and angle of internal friction (φ) were measured. The results showed that soil organic carbon content in the croplands was greater than that of desert. Nevertheless, according to findings, soil gravel, electrical conductivity, and bulk density decreased with cultivation. Compared to the desert (0.21 mm), wheat (1.71 mm) and pistachio (1.34 mm) fields had a higher dry mean weight diameter of soil. The wind erosion rate in the desert (1.48 g m−2 s−1) was 16.4 and 13.5 times greater than those of wheat and pistachio fields, respectively. Also, the wind erodible fraction in the desert was significantly higher (85%) compared to the cultivated soils (52–58%). The value of φ was greater in wheat‒cropped soil (41.05°) than in the desert (36.90°). The c values (21.39–22.46 kPa), vane shear strength (14.36–14.78 kPa) and shear strength values (22.14–23.49 kPa) in the croplands were 5.2–5.4, 5.0–5.1, and 4.9–5.2 times greater than those of desert, respectively. These results revealed that sustainable use of irrigated desert lands could be an appropriate method which significantly improves soil mechanical resistance against wind erosion.

Critical standing crop residue amounts for wind erosion control in the inland Pacific Northwest, USA

Crop residue is an important factor influencing wind erosion of cultivated soils. Establishing soil surface protection afforded by standing crop residue is critical for land managers seeking to reduce or prevent soil loss by wind erosion and the impacts of blowing dust from agricultural lands. The objectives of this study were to evaluate the effect of standing residue on soil wind erosion in the inland Pacific Northwest (iPNW), USA, and test the performance of the plant factor algorithm of the Agricultural Policy/Environmental eXtender (APEX) and Revised Wind Erosion Equation (RWEQ) models in influencing soil loss. The effect of standing winter wheat (Triticum aestivum L.), spring canola (Brassica napus L.), and chickpea (Cicer arietinum) residue on wind erosion, remaining from major commodity crops in the region, was tested in a laboratory wind tunnel using four levels of residue density. The impact of standing residue in controlling wind erosion was compared and analyzed in terms of residue density and their respective frontal area index. Our results show that residue at a density characteristic of the production environment (110 standing residue elements m−1 for winter wheat, 20 standing elements m−1 for canola, and 16 standing elements m−1 for chickpea) provided significant protection to the soil surface from wind erosion. Soil loss at this level of residue density was reduced by 73.3, 53.4, and 60.9% for respectively winter wheat, spring canola, and chickpea (frontal area indexes are 0.172, 0.104, and 0.026 respectively) compared with a surface without residue. The soil surface was found to be at significant risk from wind erosion when residue densities of the three crop types were <50% of the typical production amounts. Although not consistently significant, soil loss decreased as wind direction shifted from parallel to perpendicular with the standing residue row. The APEX model adequately simulated winter wheat and spring canola residue protection but had low accuracy in representing chickpea residue effects relative to the wind tunnel experiments. In contrast, the RWEQ model appeared inadequate in simulating soil loss for the winter wheat and canola treatments but adequately represented chickpea residue effects. Differences in model accuracy for different crop types must be considered by producers and managers to determine whether model information used to select practices to control wind erosion are likely to result in under- or over-protection of soil resources.

Localization of Soil Wind Erosion Dust Emission Factor in Beijing

Soil wind erosion dust is one of the primary sources of fine particulate matter (PM2.5). Compared with the fugitive dust emission inventory of typical domestic provinces and cities, we found that the maximum among the contribution rates of soil wind erosion dust to the local total fugitive dust PM2.5 emission inventory was about 4 orders of magnitude higher than the minimum. This study provided a wind erosion equation and a determination method of parameter values. The remote sensing interpretation, China soil dataset, and meteorological data of each district in Beijing were used to achieve the spatial distribution of the vegetation coverage factor (V), soil erodibility index (I), and climatic factors (C) in the plain area of Beijing. This study also estimated the emission factor of soil wind erosion dust and its spatial distribution. The main conclusions are as follows: ① Taking 2017 and Beijing city as an example, it was found that the climatic factor (C) was underestimated to different extents by domestic scholars, and PM2.5 emission factors were overestimated or underestimated. ② V, I, and C showed apparent spatial differences and the average values of them were 0.63±0.09, 188±73, and 0.029±0.009, respectively. The maximum values of V, I, and C were 1.5, 2.1, and 4.5 times the minimum among all districts, respectively. ③ The PM2.5 emission factor of soil wind erosion dust in Beijing showed a high spatial distribution in the northwest and southeast. The average emission factor of the city was (0.0018±0.0008) t·(hm2·a)-1, which is 0.54 times the highest emission factor (Xicheng District) and 3.12 times the lowest (Pinggu District). The area proportions of standardized emission factors with higher intensity (0.6 to 0.8] and high intensity (0.8 to 1.0] was 0.72% and 0.04%, respectively.

Abrasion of soil clods with different textures and moisture contents in sand flow environment

Abstract Abrasion is an important but complicated and fundamental process in soil wind erosion. To determine the relationship between the abrasion mass (AM) of soil clod and sand transport rate (q), and to investigate the influences of clod characteristics including moisture content, geometry, and soil texture on AM and on clod abrasion resistance, we conducted soil clod abrasion experiments in a wind tunnel. The soils types were aeolian sandy soil, loess soil, chestnut soil, and brown calcic soil, respectively. The abraders were the same soil as used for making the target clods. We found that moisture content obviously influenced AM, and the AM variation at relatively high friction velocity (u∗ = 0.44, 0.52, and 0.60 m∙s−1) showed different trends from those at lower u∗ (0.31 and 0.37 m∙s−1). For dry clods of each soil type, AM of the hexagonal prism clod was greater than that of cylindrical clod, but for moist clods, AM of the two geometries differed among soil types. We developed an AM prediction equation which mainly accounts for the mean particle size (d) and u∗. Using the abrasion coefficient (AC) as the abrasion resistance index, dry clods of the loess soil showed the strongest resistance, followed by clods of an aeolian sandy soil, chestnut soil, and brown calcic soil. However, AC could not quantitatively predict the resistance of moist clods.

The Effects of Wind Erosion Depending on Cropping System and Tillage Method in a Semi-Arid Region

Wind erosion is a major environmental problem in arid and semi-arid regions, where it has significant impacts on desertification and soil degradation. To understand the effects of cropping systems and tillage methods on the reduction of soil wind erosion, wind tunnel investigations were performed on soil samples from an irrigated field in an experiment conducted in semi-arid northwestern China in 2016–2018. Three cropping systems for annual spring wheat (Triticum aestivum L.)/maize (Zea mays L.) strip intercropping (W/M), a two-year wheat-winter rape-maize rotation (WRM), and a two-year wheat-maize rotation (WM)) were each evaluated with two tillage methods (conventional tillage without wheat straw retention (CT) and no-tillage with 25–30 cm tall wheat straw (NT)). The mean rate of soil erosion by wind with NT was 18.9% to 36.2% less than that with CT. With increasing wind velocity, the rate of soil erosion by wind increased for both CT and NT but was faster with CT than NT. Soil wind erosion occurred with a wind velocity ≥14 m s−1, and NT greatly decreased the rate of soil erosion when wind velocity exceeded 14 m s−1. W/M, WRM, and WM with NT increased non-erodible aggregates by 53.7%, 53.7%, and 54.9% in 2017, and 51.3%, 49.6% and 44.6% in 2018, respectively, than conventional tillage. At a height of 0–20 cm, the rate of soil transport with CT decreased with increasing height. The volume of soil transport at a height of 0–4 cm and soil transport percentage at a height of 0–4 and 0–20 cm (Q0–4/Q0–20) with NT were less than with CT. These findings show that NT with cropping system intensification can be an effective strategy for resisting wind erosion in irrigated semi-arid regions, thereby reducing the negative environmental impacts of crop production.

Influence of clay amendment on soil physical properties and threshold friction velocity within a disturbed crust cover in the inland pacific Northwest

Soil wind erosion is initiated when the surface friction velocity (u*) exceeds the threshold friction velocity (u*t) of soils. Soil clay content is a primary soil component influencing soil erosion. Few studies have tested the effect of clay amendment on u*t, especially in the inland Pacific Northwest (iPNW) where there is a high wind erosion risk due to the arid and semi-arid environment. The objective of this study was therefore to evaluate the effect of soil clay amendment (Wyoming bentonite) on u*t. Bentonite clay was added to four soil types prior to wetting the treated soil to create complete crust cover. The treated soil was then subject to simulated tillage to create an erodible soil surface before determining u*t in a wind tunnel. Clay amendment did not directly impact u*t, but did impact crust and aggregate properties. Crust crushing energy appeared to increase binomially with increasing clay amendment. Statistically significant relationships were found between crust crushing energy and aggregate geometric mean diameter (GMD) and between aggregate GMD and u*t. Clay amendment therefore appeared to indirectly impact u*t due to its impact on aggregate GMD. Our results were similar to previous studies that clay amendment can be effective in stabilizing erosive sandy soil ecosystems.

Sugarecane molasse and vinasse added as microbial growth substrates increase calcium carbonate content, surface stability and resistance against wind erosion of desert soils

Wind erosion is one of the main factors of soil degradation and air pollution in arid and semi-arid regions. In this study we evaluated microbial-induced carbonate precipitation (MICP) as an alternative soil conservation method against wind erosion using sugar cane molasse and vinasse as growth substrates in comparison to tryptic soy broth (TSB). The three substrates were applied in laboratory tests with and without addition of MICP cementing solution (1 M urea plus calcium chloride) to two sandy soils differing in calcium carbonate content. The performance of MICP solution inoculated with a cultured urease-producing strain of Sporosarcina pasteurii was compared to that of an autoclaved MICP solution. For control we also performed a blank treatment without substrate, MICP solution and inoculation. In addition to lab tests in which we determined the effects of treatments on soil pH, electrical conductivity (EC), calcium carbonate (CaCO3) content and surface penetration resistance, we performed wind tunnel experiments to determine soil loss by deflation under different wind velocities. Applying vinasse and molasse strongly increased soil CaCO3 content and penetration resistance, with and without addition of inoculated or non-inoculated MICP solution. Vinasse generally had stronger effects than molasse, while TSB was less effective, especially on penetration resistance. The addition of MICP solution in most treatments did not enhance but rather decrease the substrate effects. In the treatments with vinasse and molasse, increase in penetration resistance translated into substantially decreased soil loss in the wind tunnel tests, down to around one third of the loss in the blank treatment. In contrast, soil loss substantially increased in the treatments with TSB, probably due to the high input of sodium with this substrate. Our results show that molasse and, even more, vinasse can have a strong soil stabilization effect against wind erosion, which is primarily related to the formation of CaCO3 content and does not depend on additional amendments. Thus, these substrates have a great potential to be used on their own as environmentally friendly and cost-effective amendments to control wind erosion of bare sandy soils in arid environments.

Application of a new wind driving force model in soil wind erosion area of northern China

The shear stress generated by the wind on the land surface is the driving force that results in the wind erosion of the soil. It is an independent factor influencing soil wind erosion. The factors related to wind erosivity, known as submodels, mainly include the weather factor (WF) in revised wind erosion equation (RWEQ), the erosion submodel (ES) in wind erosion prediction system (WEPS), as well as the drift potential (DP) in wind energy environmental assessment. However, the essential factors of WF and ES contain wind, soil characteristics and surface coverings, which therefore results in the interdependence between WF or ES and other factors (e.g., soil erodible factor) in soil erosion models. Considering that DP is a relative indicator of the wind energy environment and does not have the value of expressing wind to induce shear stress on the surface. Therefore, a new factor is needed to express accurately wind erosivity. Based on the theoretical basis that the soil loss by wind erosion (Q) is proportional to the shear stress of the wind on the soil surface, a new model of wind driving force (WDF) was established, which expresses the potential capacity of wind to drive soil mass in per unit area and a period of time. Through the calculations in the typical area, the WDF, WF and DP are compared and analyzed from the theoretical basis, construction goal, problem-solving ability and typical area application; the spatial distribution of soil wind erosion intensity was concurrently compared with the spatial distributions of the WDF, WF and DP values in the typical area. The results indicate that the WDF is better to reflect the potential capacity of wind erosivity than WF and DP, and that the WDF model is a good model with universal applicability and can be logically incorporated into the soil wind erosion models.

Threshold friction velocities influenced by standing crop residue in the inland Pacific Northwest, USA

AbstractCrop residue is an important factor affecting soil wind erosion. Few studies have tested the effects of crop residue on threshold friction velocities (U*t) which not only controls the initiation of wind erosion events but also the frequency and intensity of erosion events and thus the rate of land degradation. This study measured the threshold friction velocity (U*t) and aerodynamic roughness length (Z 0) in the presence of winter wheat (Triticum aestivum L.), canola (Brassica napus L.), and garbanzo (Cicer arietinum) standing residue arrays to identify the sheltering capability against wind erosion of these different vegetation patterns. The influence of crop residue density and lateral cover (total roughness frontal area to soil surface area) on U*t and Z 0 was tested in a wind‐tunnel. The results indicated U*t increased linearly with residue density for the three residue types and a similar trend was found for Z 0. However, U*t and Z 0 varied among crop residue types at the same residue density or frontal area index (λ). Based on the slope of regression analysis, U*t and Z 0 of garbanzo were 40 and 25% higher than winter wheat and 43 and 119% higher than canola. This study suggested that crop residue type is important in determining U*t and Z 0 when modeling wind erosion.

Experimental study on the effect of plant spacing, number of rows and arrangement on the airflow field of forest belt in a wind tunnel

Forest belts play an important role in soil wind erosion control and the prevention of aeolian sand movement in arid and semiarid regions. In order to reveal the effect of plant spacing, number of rows, and arrangement on airflow of forest belt, the airflow fields were measured in a wind tunnel for artificial single-row forest belts with different plant spacings, forest belts with different numbers of rows with the same plant spacing, and two rows of forest belts with different arrangements. The results indicate that for the single-row forest belt, the downwind airflow decreases in the canopy area and then recovers exponentially. As the plant spacing increases, the characteristic length of the downwind airflow recovery of the forest belt and the distance at which the minimum wind speed is located both decrease approximately exponentially. As the number of rows in a forest belt increases, the downwind airflow speed in the canopy area decreases. The average reduction of downwind relative wind speed decreases with plant spacing and increases with the number of rows. A forest belt with staggered arrangement has lower downwind speeds and a longer characteristic length of airflow recovery than that in rectangular arrangements.

Evaluation the efficiency of different mulches to combat wind erosion of sandy soil running title: Efficiency of different mulches to control wind erosion

This study was conducted to determine the most suitable mulch regard to environmental adaptation. It was carried out as a completely randomized design with treatments including cement mulch (50 g cement +100 g sand +1000 ml H2O), two rates of polymer (5 and 10 g polyvinyl acetate + 1000 ml H2O), two rates clay mulches (100 and 200 g zeolite + 1000 ml H2O, 100 and 200 g bentonite + 1000 ml H2O), and control (1000ml H2O). After applying the treatments, trays containing moving sands together with different mulches air dried and the rate of soil erosion was measured during 20, 40 and 60 minutes by wind tunnel at a speed of 85 km h-1. In addition, the penetration resistance, the abrasion resistance, crust thickness, and the impact strength were measured. Data were analyzed using SPSS software. The results of this study showed that the applied treatments increased the penetration resistance, crust thickness, impact strength, and abrasion resistance and reduced the wind erosion; so that 10g of polymer mulch and 200 g bentonite have the highest resistance against wind erosion and are recommended as suitable treatments for stabilization the moving sands in arid lands such as studied area.

Ecological and environmental consequences of ecological projects in the Beijing–Tianjin sand source region

Abstract Evaluation of influences of the Beijing–Tianjin Sand Source Control Project on soil wind erosion and ecosystem services is imperative for mastering the benefits and drawbacks of the program, as well as for distinguishing more reasonable estimations to evaluate regional sustainable development. Within the Beijing–Tianjin Sand Source Region, we quantified the spatiotemporal patterns of land use/cover changes (LUCCs), soil wind erosion modulus (SWEM), and essential ecosystem services throughout 2000–2015 by utilizing field investigations, remotely sensed data, meteorological data, and modeling. The influences of ecological projects on wind erosion and ecosystem services has been subsequently assessed by using those modifications brought on via the LUCCs (e.g., conversion from cropland to grassland/woodland) during the ecological construction. The results indicated that the SWEM showed a decline and ecosystem services which included carbon storage, water retention, and air quality regulation exhibited growth driven by using both local climate exchanges and human activities such as ecological projects. Excluding the effects of climate factors, the LUCCs stemming from ecological projects caused a total SWEM decrease of 3.77 million tons during 2000–2015, of which approximately 70% was prompted by the way of the transition from desert to sparse grassland. And from this transition, ecosystem services including both water retention and aboveground net primary productivity manifest a general increase. The sub-regions of desert grassland in Bayannur, Ordos Sandy Land, and Otindag Sandy Land were hot spots for wind erosion declines and ecosystem service enhancements induced by the ecological projects. We recommend that endeavors be coordinated toward the scientific management of the degraded lands and distribution of the local populace, as well as the implementation of diverse measures in the expected hotter and drier future.

Modeling Soil Wind Erosion From Agroecological Classes of the Pacific Northwest in Response to Current Climate

AbstractSoil wind erosion is a major concern of the agricultural community in the inland Pacific Northwest (iPNW) United States. This study quantitatively predicts dust emissions from agroecological classes (AECs) of iPNW based on soil and land use types in response to climate change. The Wind Erosion Prediction System (WEPS) was used to simulate daily soil and PM10 (particulate matter ≤10 μm in aerodynamic diameter) loss at 29 meteorological stations across the iPNW. From 2009 to 2018, annual soil and PM10 loss decreased 1.18 and 0.05 kg m−2 yr−1, respectively. We presume that this decrease may be due to decreased wind speed, rather than other parameters like precipitation or solar radiation. St. John, WA had not only the highest annual soil loss but also the greatest mean wind speed and number of events with wind speeds &gt;8 m/s. However, Lind, WA appeared to have greater soil surface erodibility in terms of greater rates of hourly soil and PM10 loss. Wind erosion occurred most frequently during March and April. The average maximum annual soil and PM10 loss in the grain‐fallow stable (24.7 and 0.63 kg/m2, respectively) exceeded that of all other agroecosystems. This suggested that maintaining crop cover is critical for protecting the soil surface from erosion.

基于规划目标的京津风沙源治理区生态保护与修复效应

PDF HTML阅读 XML下载 导出引用 引用提醒 基于规划目标的京津风沙源治理区生态保护与修复效应 DOI: 10.5846/stxb201806161346 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务专项（GYZX190204）；国家重点研发计划项目（2017YFC0506500）；中国科学院前沿科学重点研究项目（QYZDB-SSW-DQC005） The ecological effects of ecosystem conservation and restoration in Beijing-Tianjin sand source regions based on the planning objects Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为改善和优化京津及周边地区生态环境状况，减轻风沙危害，2003年启动实施了京津风沙源治理工程。基于工程规划目标评估了京津风沙源治理区生态保护与修复效应，结果表明：（1）草地和林地作为京津风沙源治理区绿色生态屏障的主要组成，分别占治理区面积的57.3%和9.7%，而风沙策源地的耕地和沙地分别占17.2%和6.4%。（2）2003-2017年，京津风沙源治理区草地、耕地、沙地面积减少，而林地和其他类型面积增加。治理区植被覆盖度平均提高了2.3%，其中林地提高了4.3%，草地提高了2.4%。（3）沙尘天气发生的春季，治理区土壤风蚀量减少了54%。在防风固沙服务总量的贡献中，草地和沙地贡献了71%。因此，草地和沙地生态系统的植被恢复，对治理区生态系统防风固沙服务的提高发挥了最为重要的作用。（4）除治理区植被有所恢复外，由于气候整体变暖，近15年风场强度有所减弱，特别是沙尘天气易发生的春季风场强度减弱近45%，也是影响京津风沙源治理区风蚀量下降的一个重要原因。 Abstract:In order to improve and optimize the ecological environment in Beijing, Tianjin and surrounding areas, and mitigate the hazards of wind and sand, the Beijing-Tianjin Sand Sources Control Project (BTSSCP) was launched in 2003. The ecological effects of the BTSSCP were assessed according to the planning objects. The results showed that (1) the main parts of green ecological barrier in Beijing-Tianjin sand source regions were grassland and forest that accounted for 57.3% and 9.7% of the total area respectively, followed by cropland and sandy land that accounted for 17.2% and 6.4% of the total area respectively. (2) In 2003-2017, the area of grassland and cropland in the project region of first-stage BTSSCP decreased, while the area of forest and sand land increased. The area of the grassland, sand land and cropland in the project region of second-stage BTSSCP increased and the forest area decreased. In the past 15 years, the average vegetation coverage in the project region of BTSSCP increased by 2.3%, and the natural vegetation with increased coverage accounted for about 63% of the total area, of which the vegetation coverage of forest increased by 4.2% and the grassland increased by 2.4%. However, the average vegetation coverage in desert steppe did not increase. (3) From 2003 to 2017, the amount of soil wind erosion in the project region of BTSSCP reduced by 54%. In the total amount of soil erosion, the dust materials that can be transported remotely and directly had a direct impact on Beijing, Tianjin and Hebei were also reduced. (4) Among the factors that control soil wind erosion, the dominant grassland and sandy land contributed to 71%, which played an important role in improving the sand fixation service of the vegetation in sand source regions. In addition, the intensity of wind in spring reduced by 45% was also an important factor affecting the decrease of wind erosion in the project region of BTSSCP. 参考文献 相似文献 引证文献

Effect of transverse ridge microtopography on the surface shear stress distribution and soil wind erosion

Through wind tunnel experiments, we measured the surface shear stress (τs) on a bed surface that contained widely but uniformly spaced non-erodible ridges. We found that when the ridge spacing is larger than 10 times the height (H), the τs between two adjacent ridges could be divided into two sections. In each section, shear stress gradually increases and then decreases. The first section appears to be produced by the reverse-flow vortex that develops close behind upwind ridges and the second appears to result from airflow recovery followed by blockage by the downwind ridge. The mean surface shear stress (τs¯) of the total bed increases with increasing ridge spacing and friction velocity, and decreases with increasing ridge density. The spatial differences in τs lead to a non-uniform distribution of wind erosion between the ridges. Based on the threshold shear stress (τt) of the tested soil, we revealed a regular distribution of effective shear stress (τeff) on the sand bed, and established quantitative relationships among mean effective shear stress (τeff¯), H, ridge spacing (L), friction velocity (u*), and the threshold friction velocity (u*t) for sand entrainment: τeff¯=aLHu*-u*t2.

Predicting the spatiotemporal variation in soil wind erosion across Central Asia in response to climate change in the 21st century

Wind erosion is an important environmental issue in Central Asia (CA), which includes Xinjiang, China (XJ-China), and the five CA states of the former Soviet Union (CAS5). Future climate changes could accelerate wind erosion in arid and semiarid areas and negatively impact local soil health and productivity. Based on the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b) climate model, we simulated the spatiotemporal dynamics of soil wind erosion from 1986 to 2099 in CA using the revised wind erosion equation (RWEQ) model. Our analysis indicated that the annual soil wind erosion modulus during the prediction period (2006–2099) increased compared with that in the reference period (1986–2005), especially in the 2030s (18.71%) and 2050s (18.85%) under RCP4.5. Spring and winter soil wind erosion will be the major contributors to increased annual wind erosion. We predicted that spring soil wind erosion will increase by 10.34% (RCP4.5) to 10.71% (RCP8.5) and that winter soil wind erosion will increase by 23.32% (RCP4.5) to 33.74% (RCP8.5) in the late 21st century. Annual soil wind erosion will increase in the northwest of CA, but decrease in the Karakum Desert, Kyzylkum Desert and Taklimakan Desert. Soil wind erosion varies under different plant functional types. By the late 21st century, the soil wind erosion modulus in grassland, irrigated cropland and rainfed cropland will increase by 62 t/km2/a (RCP4.5) to 412 t/km2/a (RCP8.5), 27 t/km2/a (RCP4.5) to 88 t/km2/a (RCP8.5) and 141 t/km2/a (RCP4.5) to 237 t/km2/a (RCP8.5), respectively. Our study indicates high risks of soil wind erosion in northwestern CA, and ecological engineering measures such as nature based solutions including ecological barriers should be developed to prevent soil loss in central and western Kazakhstan, where future warming will bring severe stress.

Wind erosion rate for vegetated soil cover: A prediction model based on surface shear strength

Vegetation is regarded as the most effective measure for soil erosion control and sand control projects, which plays an important role in controlling soil wind erosion and sand disasters in arid and semiarid regions. Most of the existing models for soil wind erosion rate prediction are based on empirical results that consider factors such as vegetation coverage and wind speed but have rarely investigated the wind erosion rate from the shear strength perspective, which is also an important reason why it is difficult for existing wind erosion models to be popularized. In fact, the presence of vegetation alters the distribution of the near-surface airflow field and thus profoundly changes the magnitude and spatial distribution of shear stress generated by airflow on soil particles. According to existing theories, it is very difficult to describe these processes. Although the shear stress on a vegetation-covered soil surface may be measured using existing observation techniques, difficulties in technology make it impractical for conducting at a large scale. Consequently, research that combines soil wind erosion and the shear strength of vegetation-covered soil surfaces has rarely been reported. Therefore, the prediction of discrete wind erosion rates considering the uneven spatial distribution of the airflow field has gradually become a new trend in the study of the wind erosion of vegetation-covered soil surfaces. In this study, the model for the airflow field of a single plant and the conversion model for the airflow field from a single plant to multiple plants were examined, based on which parameters, such as vegetation characteristics and plant density in wind tunnel tests, were combined to simulate the spatial distribution of the airflow field over vegetation cover surface under four different vegetation coverages. A method for calculating the effective shear strength of the vegetation-covered soil surface was proposed, and the effective shear strength of the surface with different vegetation covers was determined. The effective shear strength of the vegetation-covered soil surface was found to increase with increasing wind speed, decrease with increasing vegetation coverage, and decrease with increasing particle size. On this basis, the relationship between the wind erosion rate q and the effective shear strength τeff¯ of the vegetation-covered soil surface was quantitatively established as q=kd/g·τeff¯, where k = 114.02. Findings of this study help to explain the wind erosion dynamics of a vegetation-covered soil surface and can also provide a solid foundation for constructing a wind erosion prediction model based on the theory of dynamics.

Ecological and economic benefits of planting winter rapeseed (Brassica rapa L.) in the wind erosion area of northern China

Winter and early spring wind soil erosion have considerable impacts on ecosystems, human well-being and agricultural production in the low precipitation zones of northern China. Little is known about the impact of growing winter rapeseed on ecological cropping systems and the associated economic benefits in the wind erosion area. To explore the winter rapeseed cover effect, we conducted a field experiment in which we covered the soil with winter rapeseed, winter wheat and wheat stubble at different plant density levels and used the spring bare ground as the control (CK). The effects of wind erosion, the “winter rapeseed + ” multiple cropping system, and the economic benefits were compared. There was a large difference in the dry matter, the maximum water absorption, the maximum water storage, the soil evaporation and total wind erosion, the amount of sediment transported in the stratum and the wind erosion modulus. Among them, the mean wind erosion modulus of spring sowing bare land was as high as 490.9 kg·hm−2·h−1, which was 7 and 13 times that of winter wheat and winter rapeseed, respectively. As the wind speed increased from 14 to 22 m·s−1, from a small density to a large density, the mean wind erosion modulus decreased from 68 to 17 kg·hm−2·h−1 for winter rapeseed, and 150 to 31 kg·hm−2·h−1 for winter wheat. Total wind-erosion of sediment transport of CK was 18.6 g·m−2 min−1, which was 16 and 31 times the mean value of winter wheat and winter rapeseed, respectively. “Winter rapeseed + ” replanting peanuts, potatoes, rice, seed melons and other crops generally increased the production value by 5–74% compared with wheat and corn intercropping, which was 98–255% higher than the traditional wheat single crop. Our results suggested that the suitable area for planting winter rapeseed in northern China was approximately 3.3 × 106 hm2, and in terms of the best economic and ecological effects, the appropriate density was 5 × 105 plants·hm−2 in northern China. Our results indicated that Chinese winter rapeseed was the best choice for preventing wind erosion and improving ecological and economic benefits in winter and spring in northern China; additionally, winter rapeseed has important impacts on agricultural sustainability in semi-arid and arid climates.