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-km2 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 （I） were all moderately spadaUy 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 andJ 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.

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.

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°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°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.

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.

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.

论早期匈奴的地望与文化

战国至汉代匈奴的历史大致可分为早、中、晚期三大阶段。早期指战国至西汉早期,此时匈奴的统治中心应在漠南,即河套及大青山一带。近年在蒙古国境内发现的“燕然山铭”,不足以构成此观点的反证。内蒙古中南部东周至秦代的牧业文化自东向西有毛庆沟类型、西园类型、桃红巴拉类型,只有桃红巴拉类型与中晚期匈奴墓反映出的匈奴族固有传统特征最吻合,应是早期匈奴的文化。毛庆沟、西园类型则分别是楼烦、林胡遗存。三者在生业方式、社会分化、对外交往等方面存在明显差异。匈奴崛起于漠南,有其必然性。

多能互补能源基地多目标多时间尺度优化调度研究

针对“风光火”一体化调度模式下的能源基地经济稳定运行与规模化新能源高效消纳问题,提出了一种融合多目标多时间尺度的多能互补优化调度模型,充分考虑能源基地不同运行工况下的优化侧重点,分别以新能源消纳最大、机组调峰成本最低、系统运行经济性最优为目标,在满足安全约束条件下利用分支切割法进行求解,并基于日前-日内多时间尺度协调调度架构实现计划的滚动修编,通过选取内蒙古某大型能源基地作为算例进行分析。结果表明,所提模型能够有效提升“风光火”协同发电能力,在保障能源基地安全稳定运行的同时促进新能源的高效消纳,提高系统运行经济性。

基于改进域对抗网络的新能源基地风光时序功率曲线生成方法

准确刻画风光时序功率曲线对于加快推动新能源大规模并网、指导联合发电系统规划运行具有重要意义。针对我国沙漠、戈壁、荒漠等地区新建大型风电光伏发电基地无历史功率数据可利用的现状,该文提出基于改进域对抗网络(improved domain adversarial neural networks,IDANN)的新能源基地风光时序功率曲线生成方法。以历史气象和功率数据充足的新能源场站作为源域,仅有气象数据的新建基地作为目标域。将源域上学习的输入气象信息到输出风光功率的非线性映射知识迁移到目标域,并添加最大均值差异(maximum mean discrepancy,MMD)作为度量域间特征分布相似性的损失函数以降低目标域泛化误差。最后采用实际风光场站算例验证所提方法的有效性,并进一步表明该方法的实用价值和意义。

飞轮储能阵列系统协调控制方法综述

因受材料、成本和技术等因素制约,提高单个飞轮储能装置的容量较为困难,难以满足长时间大功率的需求。对此提出使用飞轮阵列来提高飞轮系统的总储能容量,进而降低装置的研发和生产成本。对于飞轮阵列储能系统,研究各储能单元协调控制、相互配合的控制策略是实现阵列高效、安全运行的解决方案。从飞轮储能阵列系统拓扑结构、协调控制策略及协调控制算法进行全面的综述。从飞轮储能阵列不同并网拓扑结构出发,探讨了适用于直流母线并联和交流母线并联对应的功率分配控制策略;随后以飞轮储能阵列并行接入电网为切入点,分别对集中式、主从式与分布式协调控制算法进行比较研究和归纳总结,重点评述了分布式一致性算法优势,并在此基础上进一步总结基于智能算法高效率求解的功率分配控制策略。最后,指出了飞轮储能阵列系统并网运行协调控制面临的挑战。

北山荒漠戈壁浅覆盖区萤石矿定位技术研究

在我国的西北部地区,特别是东天山—北山成矿带中新生界覆盖区广泛分布,仅戈壁、沙漠覆盖区就占据了全国陆地总面积的12.3%。随着东部矿产资源的开发程度日益提高,西北部大面积的戈壁荒漠浅覆盖区有望成为有利的矿产资源接替基地。因此,在戈壁、沙漠等中新生界覆盖区开展矿产综合定位预测工作是当前形势下最佳的选择之一。

基于成矿构造圈定的柴北缘双口山荒漠景观区地球化学异常特征及其地质意义

大部分的热液矿床受断裂构造控制,但是基于成矿构造圈定地球化学异常的方法应用目前尚处于探索阶段。柴北缘双口山地区位于青海最重要的柴达木盆地北缘金铅锌银铅锌成矿带上,但该区内广泛分布有荒漠、戈壁等景观,且遭受风成沙等因素的影响,致使诸多地质异常信息被削弱或掩盖,对地质找矿工作造成了一定程度的干扰。针对双口山地区独特的地貌特征及成矿背景,基于成矿构造地球化学方法,对该地区其HS-9-5异常地段1∶1万土壤地球化学测量数据处理,快速优选出了有利地段,经验证发现了多条金矿(化)体。研究结果表明基于构造圈定地球化学异常的方法在构造活动强烈或在明显受构造控制的矿床的勘查工作中效果较佳,是一种值得进一步推广的地球化学勘查方法。本文主要简述其勘查过程及效果,为下一步研究区及相似景观区的矿产勘查工作提供一定的参考。

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。

面向沙戈荒区域新能源消纳的电力系统日前低碳调度策略

针对在沙漠、戈壁、荒漠区域的新能源机组面临消纳和经济性差等问题,提出一种面向沙戈荒区域新能源消纳的电力系统日前低碳调度策略。考虑系统结构的复杂性,采用模型分层的优化方案。上层模型以需求响应(DR)调用成本最小和优化负荷与风光预测总值协方差最大为目标,旨在优化用电负荷曲线,释放电网新能源消纳潜力;下层模型通过协调风电机组、光伏机组、储能电站、火电机组以及上层模型得到的优化负荷,同时将阶梯型的碳交易成本引入到目标函数中,建立多目标“源网储荷”协同低碳调度模型,旨在提高系统运行的经济性,降低系统的碳排放量,提高新能源的消纳能力。最后基于改进的IEEE 30节点系统进行仿真测试,结果验证了模型的有效性。

荒漠浅覆盖区萤石矿定位预测技术研究

北山地区是中国西北部重要的萤石成矿带,区内成矿地质条件优越,但地处戈壁荒漠,受浅覆盖层影响,地表仅可观察到极少量露头,需开展综合地球物理研究为区域成矿潜力及覆盖区下方矿脉赋存空间进行定位预测研究。以北山成矿带东段花石头山地区为示范,采用高精度磁法、激电中梯、地面伽马能谱测量、便携式X射线荧光分析及音频大地电磁测深等技术手段进行综合探测,其中面积性激电和磁法工作可有效识别隐伏赋矿空间分布,地面伽马能谱测量、便携式X射线荧光分析约束赋矿空间的矿化异常,音频大地电磁测深构建了隐伏萤石矿赋存位置深部结构模型,并通过工程验证方法组合的有效性。本研究建立了综合地质-地球物理定位预测技术方法组合,可为北山成矿带及戈壁荒漠浅覆盖区萤石矿定位预测提供理论和技术支持。

含构网型储能的沙戈荒新能源基地故障穿越策略

针对沙戈荒地区地理位置较偏远且网架结构薄弱,受变流器电流限幅与其控制回路暂态稳定性的影响,基地内构网型储能的暂态控制通常被切换为跟网控制策略,在缺乏电网强支撑的新能源基地内的风电、光伏和储能等电源极易因电压跌落而失稳,从而对整个基地故障穿越造成不利影响的问题,基于新能源基地变流器暂态控制方式的差异,分析得出,电网故障下跟网型新能源电源与构网型储能(故障期间仍为构网型控制)变流器控制失稳的关键因素为直流母线电压脉动和功角失稳等,并进一步推导了跟网型与构网型变流器在各自稳定运行范围内所能发出的最大无功功率计算表达式,提出了不同有功功率输出工况下风电场、光伏电站与储能系统的最大极限无功补偿的协同控制策略,以提升沙戈荒新能源基地故障穿越能力。最后基于PSCAD/EMTDC搭建沙戈荒新能源基地电磁暂态模型,验证了所提策略的有效性。

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。

沙戈荒大基地风电项目集电线路选型及优化研究

针对沙戈荒大基地风电项目的特殊气候与地质条件,系统进行了集电线路的选型与优化研究。首先,对集电线路的回路数量与路径进行了分析,根据负荷需求明确了回路划分原则;其次,依据载流量需求确定了导线截面,选定了适宜的杆塔型式与构造;再次,分析了地质条件,优化了基础型式以降低基础成本并提升稳定性;最后,研究了防风拉线金具的设计与固沙方案的实施。项目预测集电线路优化将实现成本节约并提高运行可靠性,为风电项目提供经济、有效的集电线路设计方案。

内蒙古四大沙漠地区风电大基地机组选型分析

利用2020—2022年ERA-5再分析资料及8个测风塔完整年数据,对内蒙古四大沙漠的风速、温度等自然条件进行统计分析,结果表明,四大沙漠地区具有丰富的风资源条件,适合风电能源的开发,且风力发电机组设计条件可满足四大沙漠地区的湍流与极端温度环境。以当前风电市场的5种机型为例,对不同方案在沙漠地区大基地项目中的发电量、静态投资、内部收益率进行分析讨论,定性对比各机型的经济性差异,结果表明长叶轮、大容量风机更符合高经济性的市场需求。

高比例新能源接入下内蒙古电网发展结构研究

为了安全稳定地实现新能源电力的送出,内蒙古电网未来将建设多回“网对网”直流通道用于将清洁能源电力送至其他省区域电网,但在部分直流故障下,内蒙古电网仍存在暂态、动态稳定问题,需从规划层面对内蒙古电网主网架进行优化。在分析当前网架适应性的前提下,对比异步联网工程、内部加强工程和外部特高压延伸工程,分析不同工程可能出现的频率稳定、动态稳定以及短路电流问题,认为未来内蒙古电网与华北电网可采用异步联网或特高压交流联络网架,能够较好地满足直流通道接入需求。