Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China

The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions: no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m(i.e., 13 H, where H denotes the fence height) downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through.

Effect of stones on the sand saltation threshold during natural sand and dust storms in a stony desert in Tsogt-Ovoo in the Gobi Desert,Mongolia

Non-erodible elements such as stones and vegetation are key to controlling wind erosion and dust emission in drylands.Stony deserts are widely distributed in the Gobi Desert,but the effect of stones on wind erosion and dust emission have not been well studied,except under artificial conditions.In this study,we evaluated the effect of stones on wind erosion and dust emission by measuring the sand saltation threshold in a stony desert in Tsogt-Ovoo in the Gobi Desert,Mongolia,under natural surface conditions during sand and dust storms.We quantified the amount of stones by measuring the roughness density,and determined the threshold friction velocity for sand saltation by measuring wind speed and sand saltation count.Our results showed that the threshold friction velocity increased with the roughness density of stones.In the northern part of the study area,where neither a surface crust nor vegetation was observed,the roughness density of stones was 0.000 in a topographic depression(TD),0.050 on a northern slope(N.SL),and 0.160 on the northern mountain(N.MT).The mean threshold friction velocity values were 0.23,0.41,and 0.57 m/s at the TD,N.SL,and N.MT sites,respectively.In the southern part of the study area,the roughness density values of stones were 0.000 and 0.070-0.320 at the TD and southern slope sites,respectively,and the mean threshold friction velocities were 0.23 and 0.45-0.71 m/s,respectively.We further compared the observed threshold friction velocities with simulated threshold friction velocities using Raupach's theoretical roughness correction and the measured roughness density values,and found that Raupach's roughness correction worked very well in the simulation of threshold friction velocity in the stony desert.This means that the results of our stone measurement can be applied to a numerical dust model.

Spatial pattern of plant species diversity and the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China

Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes in desert ecosystems, however, has received little attention in that regard. In this study, we conducted a quantitative field survey(including 187 sampling plots) in a 40-km^2 study area to determine the spatial pattern of plant species diversity and analyze the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China. A total of 42 plant species belonging to 16 families and 39 genera were recorded. Shrub and semi-shrub species generally represented the major part of the plant communities(covering 90% of the land surface), while annual and perennial herbaceous species occupied a large proportion of the total recorded species(71%). Patrick richness index(R), Shannon-Wiener diversity index(H'), Simpson's dominance index(D), and Pielou's evenness index(J) were all moderately spatially variable, and the variability increased with increasing sampling area. The semivariograms for R and H' were best fitted with Gaussian models while the semivariograms for D and J were best fitted with exponential models. Nugget-to-still ratios indicated a moderate spatial autocorrelation for R, H', and D while a strong spatial autocorrelation was observed for J. The spatial patterns of R and H' were closely related to the geographic location within the study area, with lower values near the oasis and higher values near the mountains. However, there was an opposite trend for D. R, H', and D were significantly correlated with elevation, soil texture, bulk density, saturated hydraulic conductivity, and total porosity(P<0.05). Generally speaking, locations at higher elevations tended to have higher species richness and diversity and the higher elevations were characterized by higher values in sand and gravel contents, bulk density, and saturated hydraulic conductivity and also by lower values in total porosity. Furthermore, spatial variability of plant species diversity was dependent on the sampling area.

The Expanding Earth: Indisputable Evidences of the Gobi Desert

The most striking contrasts that are found on the continents in paleogeographic reconstructions of the end of the Mesozoic era are the occurrence on the place of the disappeared humid subtropics of the largest Gobi Desert in Eurasia with air temperatures falling below 50&#176;from the freezing point and annual precipitation totals at the level of 100 mm. Science does not know the processes that can lead to a cooling of the atmosphere at 70&#176;and other equally radical changes in nature with a stable position of the blocks of the earth’s crust in space. Changes in the environment of this magnitude can only be the result of land moving northward for a distance equal to about half the radius of the Earth. Titanosaurs, described by the remains in the Gobi deposits, had a body volume, which at modern gravity corresponds to a mass of 10 to 30 ton. However, animals with such a mass and such growth could not exist now. To create the necessary pressure in the vessels and provide energy to the body, Mongolian sauropods would need a heart of 2 - 3 m in diameter. Known types of muscle tissue are unable to maintain an elongated neck and head with a mass of more than a ton. The femur bones of four-legged dinosaurs had strength sufficient to move on land only animals weighing no more than 5 - 7 tons. The bones of giant bipedal dinosaurs at a constant gravitational field would have to be subjected to specific loads, several times greater than the bones of modern elephants, which is excluded. The natural conclusion about the action of a lesser gravity in the Mesozoic provides a solution to the mystery of the truly global spread in that era of bipedal mode of movement as the most energy efficient.

Women in the Gobi Desert

THE plane flew for about an hour,transporting me from Beijing to adeserted land,the Gobi desert,where sits the China Arms Testing ＆Training Target Field.For about 40 years,thousands of scientists and technicianshave made hundreds of greatachievements in the history of Chinesearms testing;among them are a lot ofunusual women making their own quietcontributions.

Comparison of dust emissions, transport, and deposition between the Taklimakan Desert and Gobi Desert from 2007 to 2011

The Taklimakan Desert(TD) and Gobi Desert(GD) are two of the most important dust sources in East Asia, and have important impact on energy budgets, ecosystems and water cycles at regional and even global scales. To investigate the contribution of the TD and the GD to dust concentrations in East Asia as a whole, dust emissions, transport, and deposition over the TD and the GD in different seasons from 2007 to 2011 were systematically compared, based on the Weather Research and Forecasting model coupled with Chemistry(WRF-Chem). Dust emissions, uplift, and long-range transport related to these two dust source regions were markedly different due to differences in topography, elevation, thermal conditions, and atmospheric circulation. Specifically,the topography of the GD is relatively flat, and at a high elevation, and the area is under the influence of two jet streams at high altitudes, resulting in high wind speeds in the upper atmosphere. Deep convective mixing enables the descending branch of jet streams to continuously transport momentum downward to the mid-troposphere, leading to enhanced wind speeds in the lower troposphere over the GD which favors the vertical uplift of the GD dust particles. Therefore, the GD dust was very likely to be transported under the effect of strong westerly jets, and thus played the most important role in contributing to dust concentrations in East Asia. Approximately 35% and 31% of dust emitted from the GD transported to remote areas in East Asia in spring and summer, respectively. The TD has the highest dust emission capabilities in East Asia, with emissions of about 70.54 Tg yr.1 in spring, accounting for 42% of the total dust emissions in East Asia. However, the TD is located in the Tarim Basin and surrounded by mountains on three sides. Furthermore, the dominant surface wind direction is eastward and the average wind speed at high altitudes is relatively small over the TD. As a result, the TD dust particles are not easily transported outside the Tarim Basin, such that most of the dust particles are re-deposited after uplift, at a total deposition rate of about 40 g m.2. It is only when the TD dust particles are uplifted above 4 km, and entrained in westerlies that they begin to undergo a long-range transport. Therefore,the contribution of the TD dust to East Asian dust concentrations was relatively small. Only 25% and 23% of the TD dust was transported to remote areas over East Asia in spring and summer, respectively.

^(10)Be in quartz gravel from the Gobi Desert and evolutionary history of alluvial sedimentation in the Ejina Basin,Inner Mongolia,China

Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate.However,such work is limited by a lack of suitable dating material preserved in the Gobi Desert,but cosmogenic 10Be has great potential to date the Gobi deserts.In the present study,10Be in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages.Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago,whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka.The latter developed gradually northward and eastward to modern terminal lakes of the river.These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin.Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin.Intense floods and large water volumes would mainly occur during the short deglacial periods.

Analysis of the Surface Energy Closure for a Site in the Gobi Desert in Northwest China

The heat storage terms over an ideal(non-vegetated) horizontal desert surface may be very important and easily neglected in surface energy balance studies.In this paper,based on a field experiment over the Gobi Desert in the middle part of the Hexi Corridor in Northwest China(39 05 N,100 16 E;1457-m elevation),we studied the energy budget closure and evaluated the contribution of the heat storage terms to the closure of the surface energy balance.There were imbalances of 8% and 15% in summer and winter,respectively,if the heat storage terms were not taken into account.For both seasons,a nearly perfect result of the surface energy closure(99%) was obtained by inclusion of the estimates of heat storage terms.The soil heat storage term improved the surface energy imbalance by about 6% in summer and 13% in winter,and the air enthalpy storage term improved it by about 0.6% in summer and 1% in winter,while the contribution of the atmospheric moisture changes could be ignored.

沙戈荒基地外送全环节经济性测算及市场竞争力分析

在风光火储打捆基地外送价格形成机制尚不明确且暂无可借鉴成熟经验的背景下,对沙戈荒基地外送经济性测算展开分析与讨论。首先考虑以系统运行成本最小为目标搭建了生产运行模拟模型,并基于经营期法和按发电量比例分配原则搭建打捆送电成本电价测算模型。以沙戈荒基地外送某典型工程为例,对基地发电、送电等外送全环节经济性进行了测算。进一步从打捆电源配置、标准煤单价、增配储能、考虑调峰收益、单位造价等几方面分析影响沙戈荒基地发电成本电价的主要因素,并通过比较受端区域燃煤发电基准价与测算的落地成本电价对市场竞争力进行分析讨论。案例的分析结果从经济成本与市场竞争力角度对沙戈荒基地外送工程规划、建设及定价机制设计具有借鉴作用,对全面贯彻落实碳达峰碳中和战略决策,服务能源转型和清洁绿色低碳发展具有重大意义。

西北干旱区荒漠戈壁两次极端沙尘事件的对比研究

为深入理解极端沙尘暴事件的演变过程和驱动因子,结合多源卫星遥感及再分析数据,挑选2007年3月31日(“3·31”事件)和2021年3月14日(“3·14”事件)爆发于西北干旱区荒漠戈壁的两次沙尘暴事件,对比分析了其时空演变、高低空环流配置、近地面气象要素的变化。结果表明:(1)两次极端事件分别爆发于塔克拉玛干沙漠及戈壁荒漠,均受高低层天气系统影响。其中,“3·31”事件受地面冷锋和高空脊控制,脊前西北冷空气与地面冷锋引起的垂直运动配合,将沙尘往下游输送;而“3·14”事件则受蒙古气旋和高空槽影响,气旋后的偏北风和气旋引发的垂直运动将沙尘卷起至高层大气,并通过槽后西北风将其往下游输送;(2)两次极端沙尘事件均有持续时间长的特点,区别在于“3·31”事件主要受高压脊、均压场和周边地形影响,大气层结稳定,沙尘不易沉降和输送,而“3·14”事件则因中国北部持续性高压导致的偏南风和偏东风阻止了沙尘向下游扩散;(3)两次极端沙尘事件爆发前,塔克拉玛干和戈壁荒漠均出现了高温、降水减少及土壤水分枯竭现象,即强风和干燥土壤。为极端沙尘事件的爆发创造了有利的动力条件和物质基础。

河西戈壁荒漠地区风积沙路段治理研究

在高速公路施工建设中,路线不可避免会穿越一些特殊土(岩)地段、不良地质地段,需要对这类特殊路基进行特殊设计与施工处理。尤其是戈壁荒漠地区风积沙路基段,通过把先进的施工技术和科学的施工管理相结合,经过工程实践,提炼与总结形成具有指导现场施工、加强项目管理的规范化技术文件,从而提升工程实体品质。

新疆戈壁滩风力发电场微观选址及风电机组选型设计

随着我国“碳达峰、碳中和”国家战略政策的实施,清洁低碳能源的供应已成为经济社会发展的主题,构建可在生能源的新型电力系统改革正在快速推进。有效开发利用新疆戈壁滩地区,建设风力发电站供应内地电力紧缺,针对新疆戈壁滩进行发电厂微观选址及风机选型,结合新疆兵团二师36团米兰200MW风力发电站项目为例,进行了系统的方案设计。

Vegetation patterns and nature reserve construction in an extremely-arid desert in Anxi, NW China's Gansu Province

Anxi County is located in the northwestern part of the Hexi Corridor in Gansu Province and has the sole national level nature reserve of extremely arid desert in China. Phytosociological methods (Braun Blanquet, 1964) are used to classify plant community types in this area. Eleven are distinguished, including six of deserts, four of oases and one transitional type between deserts and oases. Direct gradient analysis(DCA) is employed to correlate the distribution of plant communities to physiogeographic conditions. This study makes clear that water is the most important ecological factor for the distribution of plant species and communities in this area. The effects of water have been demonstrated in different ways. A vegetation gradient from lower altitude to higher altitude in the southern part of the reserve is driven by a precipitation gradient. The effects of the depth of ground water table contribute to the differentiation of vegetation from desert to oasis in the flat area. In a finer scale, the washed gullies have obviously higher species richness and also higher vegetation cover than the surround gobi surfaces, possibly caused by the effects of floods. The vegetation patterns demonstrate that the area of Anxi County is a complete landscape unit. The range of the current nature reserve is not large enough for the purpose of conserving the unique biodiversity in this area.

戈壁荒漠浅覆盖区15万区域地质填图技术方法探索--以东天山哈密地区为例

为了更好地服务生态文明建设和经济社会高质量发展,区域地质填图工作亟需从基岩区向盆山结合带、盆地等覆盖区进行拓展。戈壁荒漠浅覆盖区是研究中国北方中小城市和大城市边缘干旱区找水、隐伏区找矿、盆地基底性质、盆山耦合演化的关键地区,但一直缺乏针对性的区域地质填图技术方法。以东天山哈密地区觉罗塔格山与吐哈盆地结合部位的戈壁荒漠浅覆盖区为例,利用地质、物探、遥感、钻探等多技术手段,采用由“已知”到“未知”的思路,从调查内容、调查方法、技术手段、成果表达等方面,针对不同覆盖层深度、覆盖层结构和地质矿产目标,通过大量方法实验和实践,开展适用性、经济性和分辨率的综合分析,完善优化了地球物理和钻探的技术方法组合。利用GeoModeller软件,实现了戈壁荒漠浅覆盖区三维地质结构的可视化表达,建立了从地表、覆盖层到覆盖区基岩的立体式透明化的区域地质填图技术方法体系,查明了地质填图区域的三维地质结构及其成矿地质背景,满足戈壁荒漠浅覆盖区15万区域地质填图的目标,也为东天山大草滩断裂带性质、吐哈盆地基底性质及其中新生代盆地构造环境演化等关键地质问题提供了重要信息。

Impacts of oasis on the atmospheric hydrological cycle over the nearby desert

Using the data of “A field experiment on landatmosphere interaction over arid region in Northwest China” carried out in Dunhuang of Gansu Province from May to June 2000;Characteristics of the atmospheric humidity over desert and Gobi near oasis in the Northwest China Arid Region are analyzed. According to the difference of the characteristics in different wind directions, the impacts of oasis on atmospheric hydrological cycle over desert and Gobi near it are revealed. The relation of atmosphere inverse humidity and negative water vapor flux to wind direction and atmospheric stability is studied. It shows that distribution of the atmosphere inverse humidity is inconsistent with that of the negative water vapor flux;sometimes 1-hour-average value demonstrates the characteristic of counter-gradient transfer. And the diurnal variation of distribution of the counter-gradient transfer and the effect of atmospheric stability on the counter-gradient transfer are also given.

基于时间序列模型的戈壁荒漠露天矿生态环境评价

矿区生态环境评价中常采用单景、多景遥感数据来进行评价,但这2种数据存在时间不一致性和评估不准确性的缺点。为实现矿区生态环境的准确监测,以戈壁荒漠露天矿及其周边环境为研究对象,采用CFmask算法+Tmask算法获取纯净像元反射率。经时间序列模型合成研究区年度遥感数据,采用压力-状态-响应模型对其进行长时间序列生态环境评价。结果表明:(1)基于时间序列模型预测的地表反射率值与对应局部区域的卫星观测地表反射率值差异较小且其真彩色影像视觉差异较小,非纯净像元位置处预测反射率与周边纯净像元地表反射率真彩色影像视觉差异较小。以2022年各波段纯净像元反射率观测值与预测值验证精度,结果显示观测值与预测值显著相关(相关系数均大于0.6)。实地考察数据与经时间序列预测数据得到的生态环境指数的相关性(R^(2)=0.450)优于单景生态指数(R^(2)=0.347)、多景生态指数(R^(2)=0.386)。(2)2013—2021年研究区整体生态环境较差,呈南高北低、西高东低的空间格局,且随着时间增加,南部生态环境退化较为严重。矿区内生态环境变化较矿区外生态环境变化稳定,矿区外生态环境退化较快。(3)生态差、生态中、生态优面积的年变化速率分别为0.005/a、0.002/a、-0.007/a。各生态等级状况随时间呈现景观破碎度减小、景观异质性减小、聚合度增加态势,生态优斑块流向生态中、生态差斑块,生态差等级逐渐成为研究区生态环境主要生态等级。矿区内各等级占比稳定,矿区外生态差占比逐年增加。在对研究区进行生态修复时应尽量避免在半阳坡方向种植作物,且在阴坡、半阴坡、阳坡、半阳坡方向种植作物时均应避免坡度大于17.5°。

高密度电法与瞬变电磁法在戈壁区找水的联合应用

为准确掌握地下水资源的动态变化,有效支撑生态环境的可持续发展,在新疆哈密某矿集区利用高密度电法与瞬变电磁法联合进行物探勘查,对地下含水层与隔水层进行预判。经验证,高密度电法与瞬变电磁法的组合,有效指导水文钻探施工,为同类地质条件下物探手段的选取和应用提供参考。

新疆戈壁荒漠区典型露天煤矿土壤重金属来源解析及空间分布

查明戈壁荒漠区典型露天煤矿土壤重金属来源及其空间分布特征是准确判断和制定土壤污染治理方案的前提,然而系统的研究工作依然薄弱。本文以新疆戈壁荒漠区典型煤矿周边土壤为研究对象,系统的布设和采集了266件土壤样品,测试分析了As、Cd、Co、Cu、Cr、Hg、Ni、Pb、Zn共9种元素含量及土壤pH值。通过利用描述性统计分析、相关性分析、聚类分析以及主成分分析等多元地学统计分析方法分析研究了土壤重金属含量特征并初步识别了土壤重金属来源,使用绝对主成分-多元线性回归受体模型(APCS-MLR)和反距离加权法定量分析各污染源贡献率和重金属元素空间分布特征。结果表明:(1)研究区土壤pH平均值为8.31,9种元素含量低于土壤环境质量农业用地、建设用地筛选值,同时也低于新疆土壤重金属背景值;从各功能分区来看,仅废污水排放区As、Cd、Cu、Ni和Pb元素含量高于新疆背景值;(2)Cr、Ni、Zn、Co、Cu、As、Cd元素两两之间具有中等以上相关性,Cd与Pb具有中等程度相关性,Hg与其他8种元素相关性较弱;(3)聚类分析结果将研究区土壤重金属分为Cr-Ni-Zn-Co-Cu-As、Cd-Pb和Hg三类;(4)源解析结果表明研究区土壤重金属主要来源为成土母质源(50.902%)、废污水与煤尘源(31.507%)。

新疆辣椒戈壁滩自然干制过程监测及技术规程探究

新疆辣椒戈壁滩自然干制过程包括挂果干燥、采收、摊晒、拢堆、发汗、装袋运输6个步骤,然而干制过程以经验为主,缺乏技术规范、理论指导,且存在辣椒易碎、发霉等问题。有必要对其实际干制过程进行监测,并制订相应的技术规程,以规范辣椒的自然干制过程,保障其安全性,提高其品质。本研究跟踪了红龙18、红龙23和铁皮椒3个常见品种的自然干制过程,监测了环境温湿度及风速、辣椒干基含水量、水分活度、色差及发霉率等指标,建立新疆辣椒戈壁滩自然干制模型,其干制过程符合Logarithmic干制模型。结合实际经验,提出应在辣椒干基含水量为1.0 g/g时开始拢堆,辣椒干基含水量为0.16 g/g时自然干制结束。此外,研究发现机械采收的辣椒损伤较多,自然干制过程中更易发霉。降低采收机械对辣椒的损伤、规范自然干制过程,有利于提高干制效率,保障干制辣椒安全性,促进干制辣椒产业高质量发展。

Two energy balance closure approaches： applications and comparisons over an oasis-desert ecotone

Studies of energy balance that rely on eddy covariance(EC) are always challenged by energy balance closure, which is mainly caused by the underestimations of latent heat flux(LE) and sensible heat flux(Hs). The Bowen ratio(BR) and energy balance residual(ER) approaches are two widely-used methods to correct the LE. A comprehensive comparison of those two approaches in different land-use types is essential to accurately correcting the LE and thus improving the EC experiments. In this study, two energy balance approaches(i.e., BR and ER) were compared to correct the LE measured at six EC sites(i.e., three vegetated, one mixed and two non-vegetated sites) in an oasis-desert ecotone of the Heihe River Basin, China. The influences of meteorological factors on those two approaches were also quantitatively assessed. Our results demonstrated that the average energy closure ratio((LE+Hs)/(Rn–Gs); where Rn is the surface net radiation and Gs is the surface soil heat flux) was approximately close to 1.0 at wetland, maize and village sites, but far from 1.0 at orchard, Gobi and desert sites, indicating a significant energy imbalance at those three latter sites. After the corrections of BR and ER approaches that took into account of soil heat storage, the corrected LE was considerably larger than the EC-measured LE at five of six EC sites with an exception at Gobi site. The BR and ER approaches yielded approximately similar corrected LE at vegetated and mixed sites, but they generated dissimilar results at non-vegetated sites, especially at non-vegetated sites with low relative humidity, strong wind, and large surface-air temperature difference. Our findings provide insight into the applicability of BR and ER approaches to correcting EC-based LE measurements in different land-use types. We recommend that the BR-corrected and ER-corrected LE could be seriously reconsidered as validation references in dry and windy areas.