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The varying fetch effect of aeolian sand transport above a gobi surface and its implication for gobi development process

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International Soil and Water Conservation Research 2022年第4期10卷 623-634页

作者： Chunlai Zhang Guoru Wei Xueyong Zou Zhenting Wang Qing Li Xuesong Wang State Key Laboratory of Earth Surface Processes and Resource Ecology MOE Engineering Research Center of Desertification and Blown-sand ControlFaculty of Geographical ScienceBeijing Normal UniversityBeijing100875China Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhou730000PR China Hebei Engineering Research Center for Geographic Information Application Institute of Geographical SciencesHebei Academy of SciencesShijiazhuang050011China

The gobi deserts are important landscapes and major sandstorm source areas in arid northwestern China.Unsaturated sand flow and decreasing sand supply capacity is well known as the basic characteristics of gobi surface,but relatively little attention has been paid to the fetch effect of sand transport which is closely related to sand supply and indicative of wind erosion process in gobi.Using a field experiment,we investigated the spatial and temporal variations on a manually disturbed gobi surface downwind a sand-blocking belt and a sand-fixing belt by measuring the sand transport rate and the height profile of flux density at different fetch lengths during a sequence of wind erosion events.Results showed that the sand supply capacity determined the critical fetch length(Lc)for the sand transport rate so that the fetch effect varied with wind erosion proceeding due to depletion of erodible material.The height profile of flux density above the surface followed two distributions:an exponential decrease with increasing height,which commonly occurred above the newly treated gobi surface during the early wind erosion events;or a Lorentzian distribution with a peak flux at a certain height,which often happened in the later wind erosion events.The varying fetch effect,decreasing sand transport rates,and the nonerodible area expanded downwind are an epitome of the gobi development and expansion process from the perspective of wind erosion.

关键词： gobi Wind erosion Sand transport Fetch effect gobi development

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

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Journal of Environmental Sciences 2002年第3期14卷 380-387页

作者： LiuHY XuLH MOELab.forEarthSurfaceProcesses DepartmentofUrbanandEnvironmentalSciencesPekingUniversityBeijing100871China.E－mail：lhy@*** MOELab.forEarthSurfaceProcesses DepartmentofUrbanandEnvironme

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.

关键词： extremely arid desert vegetation pattern nature reserve Central Asia gobi

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TURBULENCE STRUCTURE AND TRANSFER CHARACTERISTICS IN THE SURFACE LAYER OF HEIFE gobi AREA

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Acta meteorologica Sinica 1992年第1期6卷 92-104页

作者：王介民刘晓虎马耀明 Lanzhou Institute of Plateau Atmospheric Physics Academia SinicaLanzhou

Based on the HEIFE 1988 and 1990 pilot observations,an analysis on the turbulence structure of gobi surface layer,mainly on the similarity formulations of wind and temperature variances,the spectra and cospectra characteristics,is presented.The phenomenon of downward water vapor flux over gobi desert in daytime is confirmed in both observations,this and the well-known‘oasis effect’are two sides of a local mesoscale circulation.

关键词： HEIFE gobi surface layer turbulence structure turbulence transfer

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Distribution and Characteristics of Nitraria sphaerocarpa nebkhas in a gobi habitat outside an oasis in Hexi Corridor region,China

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Research in Cold and Arid Regions 2012年第4期4卷 288-295页

作者： YongZhong Su Rong Yang ZhiHui Zhang MingWu Du Linze Inland River Basin Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhouGansu 730000China

Nitraria sphaerocarpa Maxim., a typical desert plant which often appears in nebkha form, is widely distributed along the periph- ery of oasis in arid regions of Northwest China, and plays an important role in desertification control around oases. In this paper, the characteristics and distribution patterns ofN. sphaerocarpa nebkhas were investigated in a gobi environment outside an oasis. Results shows that about 200 N. sphaerocarpa nebkhas per hectare was recorded and total sand sediments was 25 m3/ha. Nebkhas vary in size, and the mean height （H） and horizontal composition （L） were 15 cm and 80 cm, respectively. There exists a signifi- cant linear relationship between H and L, suggesting that the investigated nebkhas are mostly in the growth stage. The numbers, height and sand deposit ofnebkhas decreased with increasing distance away from the oasis. Grain-size analysis indicates that the mean grain size of sediments at the crests of nebkhas increased with increasing nebkha height. Organic C and total N concentra- tions were related to the mean grain size. It was concluded that N. sphaerocarpa shrubs are efficient horizontal sand traps for wind-driven sediments. A better understanding of the development of nebkha can provide information for the design of biological sand control measures around oases in add regions.

关键词： N. sphaerocarpa nebkha sediments gobi oasis Northwest China

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

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Natural Science 2010年第7期2卷 681-687页

作者： Qiang Zhang Yuhe Nan Sheng Wang 不详

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.

关键词： Desert or gobi Hydrologic Cycle Atmospheric Inverse Humidity Negative Water Vapor Flux Counter-Gradient Transfer

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Sand drift encroachment in the Dunhuang Mogao Grottoes District and its control

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Science China Earth Sciences 1997年第2期40卷 197-206页

作者：屈建军董光荣文子祥张伟民胡世雄 Institute of Desert Research Chinese Academy of Sciences Lanzhou 730000 China Institute of Geography Chinese Academy of Sciences Beijing 100101 China

Analysis on sand drift damages to the Dunhuang Mogao Grottoes showed that the actual sand drift hazards in the area are mainly attributed to the gobi wind-sand stream formed by sand coming from the Mingsha Mountain (megadune), while the migration of the megadune and its frontal edge dunes is actually not a major threat to the grottoes. The gobi belt on the cliff top of the Mogao Grottoes is not only a natural sand transport field but also a natural protective screen which prevents the megadune and its frontal edge dunes from advancing towards the grottoes or burying the grottoes. Therefore efforts to protect the Mogao Grottoes should be focussed on halting the gobi wind-sand stream rather than on checking the migration of sand dunes. For this reason, effective sand blockade and stabilization measures should be adopted at the frontal edge of the megadune but no sand retarding works are allowed to be set up in the gobi belt so as to avoid sand accumulation and entering the grottoes.

关键词： Mogao Grottoes gobi wind-sand stream sand dune migration

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Overall efficiency of a V-shaped nylon net fence in preventing sand damage to the Mogao Grottoes

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Research in Cold and Arid Regions 2012年第2期4卷 163-174页

作者： GuoShuai Li JianJun Qu WanFu Wang Wei Yang Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhouGansu 730000China The Conservation Institute of Dunhuang Academy DunhuangGansu 736200China The Economic Research Institute of Hong Kong and Macao Special Administrative Region Jinan UniversityGuangzhouGuangdong 510632China

A V-shaped nylon net fence installed in 1990 on top of the Mogao Grottoes is shown to be effectively resisting aeolian sand damage to the grottoes. The structure guides and causes deposition of sand from westerly wind （the primary hard wind）, but to some extent hinders the inverse function of easterly wind carrying sand away from the grottoes toward Mount Mingsha. The gobi side by the fence experiences higher wind speed, so that on which are easily formed undercutting pits, and the deposited sands on it generally form double-peak structures due to abundant sand sources. If the earth surface characteristics in gobi areas by both sides of the fence are quite varied, the erosion and deposition features of the accumulating sand section are similar in different seasons; however, if the earth surface characteristics are similar, the features become irregular in different seasons. Sand depositions with long slope feet are formed along the south and north sides of V-shaped nylon net fence. Disrupted by strong westerly wind and northwesterly wind, sand accumulations by north of the fence are in form of single peaks. Although the operation duration of the V-shaped nylon net fence has exceeded its design life （10 years）, our observations indicate that it is still effective in reducing wind-driven sand damages to the Mogao Grottoes, so it should not be withdrawn.

关键词： nylon net sand prevention gobi Mogao Grottoes

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gobi全球移动互联网技术通过at&t认证

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通信世界 2008年第35期 38-38页

本刊讯9月10日,at&t宣布高通公司的gobi全球移动互联网技术已经通过认证,可以在at&t移动宽带网络上使用。嵌入式gobi解决方案包括高通公司的MDM1000芯片组、相关的软件和API以及针对软件定义可配置数据调制解调器的参考设计,该调制解调... 详细信息

本刊讯9月10日,at&t宣布高通公司的gobi全球移动互联网技术已经通过认证,可以在at&t移动宽带网络上使用。嵌入式gobi解决方案包括高通公司的MDM1000芯片组、相关的软件和API以及针对软件定义可配置数据调制解调器的参考设计,该调制解调器支持HSPA和其它3G无线技术,并且完全后向兼容GPRS/ EDGE。

关键词：移动互联网技术高通公司数据调制解调器 at&t gobi

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