库姆塔格沙漠南部的风积地貌特征

通过考察结果和TM影像解译,库姆塔格沙漠的东南分布高大的沙山,沙丘形态复杂;南部和西南缘分布有多条南北走向的荒漠沟谷,两岸分布沙垄,高18~65m,垄脊点(金字塔型)线交错,沙垄走向与沟的走向一致,阶地上覆盖一层深色矿物组成的砂砾(粒径3~1mm)。沙漠的中心区域,孤立的新月型沙丘、沙丘链占优势。下伏地形强烈影响着库姆塔格沙漠的风沙地貌形态。沙漠南部的低山、阿尔金山及其山前洪积沟谷形成的沟谷效应,塑造了沙漠南部复杂的地貌形态。沙漠沙丘砂的粒径由南向沙漠中心减小,0.25~0.05mm细砂占80%左右。     

毛乌素沙地东南缘不同类型沙丘土壤水分分布特征

通过对横山县境内毛乌素沙地东南缘的实地考察,根据植被类型和植被覆盖度,将沙丘分为裸露流动沙丘、灌木覆盖沙丘、乔木覆盖沙丘,分别在各类沙丘不同地貌部位实施4 m深度钻孔取样,并进行含水量测试和粒度分析,研究沙地土壤含水量变化。结果表明:对于垂直方向0～4m深度的沙地、灌木和乔木覆盖沙丘平均含水量变化为:丘间洼地>迎风坡>背风坡,而裸露流动沙丘平均含水量变化为:丘间洼地>背风坡>迎风坡;不同类型沙丘在各地貌部位不同层段含水量变化差异明显,变化趋势不统一。沙丘的地貌部位相同,地表的植被类型和覆盖度差异是影响沙地土壤含水量的重要因素,测试结果显示,迎风坡含水量为:灌木覆盖沙丘>乔木覆盖沙丘>裸露流动沙丘;背风坡含水量为:灌木覆盖沙丘>裸露流动沙丘>乔木覆盖沙丘;丘间洼地含水量为:灌木覆盖沙丘>乔木覆盖沙丘>裸露流动沙丘。灌木覆盖沙丘土壤含水量变异系数最大,水分含量在不同层位波动较大,裸露流动沙丘和乔木覆盖沙丘含水量波动差异较小。沙丘上生长的灌木和乔木明显地改变了沙丘含水量的变化特征,灌木比乔木对沙丘含水量及其垂向变化的影响更显著。灌木对地表大气中的粉尘有较强的拦截能力,灌木沙丘平均的粉砂和黏土含量高,灌木的覆盖有利于沙地的土壤化进程和保持沙地水分,在沙地绿化过程中,应充分考虑灌木植物的作用。     

塔克拉玛干沙漠腹地横向沙丘表面紧实度分异特征

沙丘表面紧实度是量化沙丘紧实程度的一个综合性指标,紧实度指标与沙丘的风蚀与堆积成因关系密切,对风成沙丘的形成具有重要意义。基于对塔克拉玛干沙漠腹地垄间平地的4种简单横向沙丘〔饼状沙丘(PD)、盾状沙丘(SD)、雏形新月形沙丘(PCD)、新月形沙丘(TCD)〕表面紧实度、容重、孔隙度和平均粒径的测量,通过最小显著差异法(LSD)分析和多重比较,对简单横向沙丘表面紧实度的空间分异特征及其形成机制进行了分析。研究结果表明:1 4种沙丘的沙面紧实度均具有较大的空间差异性,并且此差异性具有方向性,纵向差异性最大,横向差异较小;2 4种沙丘表面紧实度平均值表现为:盾状沙丘饼状沙丘雏形新月形沙丘新月形沙丘,而紧实度空间差异性却表现为:饼状沙丘盾状沙丘雏形新月形沙丘新月形沙丘,最大值和最小值点出现的位置也不同;3沙丘表面紧实度和容重、孔隙度具有很好的相关性,在质地相似的沙物质中,容重和孔隙度均可以作为衡量紧实度的指标。     

Kdv-Burgers方程及其相变在地貌学中的应用

本文把包含有耗散项(v)和弥散项(B)的Kdv—Burgers方程作为风沙流运动的规范方程,研究了沙丘的形成过程。发现能量的散裂与能量逆转同沙丘发育密切相关,整个过程可概括为:能量散裂(B>0)→相变点(B=0)→能量集中(B<0)→相变点(B=0)→能量散裂(B>0)……对应着的过程是:小沙丘(幼年)成长为大沙丘(壮年)再发展成老年,经过相变(崩塌)再回到幼年。根据kdv—Burgers方程的行波解还讨论了风沙流的性质及沙丘移动的规律。     

新月形沙丘顶点与沙脊线重合和分离的两种过程——以甘肃河西走廊沙区为例

为了揭示新月形沙丘顶点与沙脊线重合和分离的两种过程,对甘肃河西走廊沙区绿洲边缘的新月形沙丘进行了调查观测,并在民勤绿洲边缘新月形沙丘上进行了流场观测。结果表明:1新月形沙丘的顶点与沙脊线的重合和分离两种过程交替进行,春季≥5 m·s~(-1)的NW风是沙丘顶点与沙脊线重合的主要原因,夏季≥5 m·s~(-1)的SE风是沙丘顶点与沙脊线分离的主要原因。重合的过程也是沙丘前移的过程。2沙丘顶点与沙脊线重合时,沙丘顶点的风速大于上风向旷野风速;沙丘的顶点与沙脊线分离且当旷野风速≥8 m·s~(-1)时,沙丘顶点至沙脊线之间的风速小于上风向旷野风速。3从沙丘迎风坡底部到沙丘顶部,中沙增多细沙减少;沙丘各部位的细沙粒度与≥2 m·s~(-1)的风速正相关,中沙粒度与≥2 m·s~(-1)风速为负相关;沙丘各部位粒度的不确定性是由两个相反方向的风沙流过程造成的,此过程与沙丘顶点与沙脊线重合和分离两种过程的交替进行是对应一致的。     

基于流域尺度的中国北方沙地空间分布特征

沙漠河岸是独特的地理单元,在世界主要沙漠中普遍存在,风水复合地貌过程是其独特性的突出表现.文中以中国北方三级流域中沙地为研究对象,应用景观生态学中景观指数方法,以及统计学的主成分-聚类分析方法,对流域内风沙地貌空间分布组合状况进行划分:1)山前盆地-梳状水系-片状沙丘分布.2)山地高原-辐散状水系-带状沙丘分布.3)高...     

微地形变化对沙质荒漠拟步甲科昆虫分布的影响

干旱荒漠微地形变化影响小尺度植被和土壤的分布特征,然而,如何影响拟步甲科昆虫分布的认识仍不够。以甘肃省临泽县绿洲边缘流动沙地(丘)为研究对象,采用样方法调查了丘间低地及沙丘不同部位拟步甲科昆虫的种类组成、数量及生境条件。研究发现:(1)丘间低地拟步甲科昆虫群落结构与沙丘不同并存在季节变化,5月丘间低地拟步甲科昆虫数量、多样性指数和鳖甲属昆虫数量显著高于沙丘,而8月仅有拟步甲科昆虫的数量在丘间低地显著高于沙丘;(2)5月沙丘迎风坡和背风坡拟步甲科昆虫的数量均高于坡顶,宽漠王属和东鳖甲属昆虫主要选择在沙丘迎风坡活动,而鳖甲属昆虫主要选择在沙丘背风坡活动;(3)灌木覆盖度是影响拟步甲科昆虫在丘间低地和沙丘间分布的主要环境因子,而土壤含水量是影响拟步甲科昆虫在沙丘不同部位分布的主要环境因子。总之,拟步甲科昆虫对沙丘微地形变化具有明显的选择性,而这种选择与不同拟步甲科昆虫的生理生态特征密切相关。     

采煤塌陷对固定沙丘土壤水分动态的影响研究

通过对毛乌素沙地东南边缘沙地采煤塌陷对固定沙丘的水分时空动态分布规律影响的研究表明,沙土含水量的时空变化与降雨季节和降雨量有密切关系。沙丘0-80cm土层为土壤水分受降雨影响的活跃层,其中0-40cm土层变化最为明显。沙丘的迎风坡和坡顶含水量低于沙区的其他部位,但受沙丘高度以及植被和土壤质地的影响这种差异并不明显。在沙区采煤引起的地表塌陷对土壤水分的时空变化影响较小。     

新疆温宿盐丘国家地质公园地质遗迹资源及综合评价

新疆温宿盐丘国家地质公园是我国批准的第六批国家地质公园,通过对地质公园周边地质遗迹资源的研究,证实园区拥有全世界独一无二的奥奇克葫芦状盐丘底劈构造遗迹,丰富多彩的流水侵蚀地貌与北方喀斯特地貌,及十分珍稀的雅丹地貌景观遗迹。这些丰富多彩的地质遗迹景观为规划建设一个以盐丘地质景观为主,罕见的岩石与构造地貌为辅,特色鲜明的地质公园提供了条件。     

毛乌素沙地天然臭柏种群年龄结构

以毛乌素沙地天然臭柏(Sabina vulgaris)种群为研究对象,按水分、地形等立地条件变化,将臭柏种群划分为滩地、沙丘底部、沙丘坡面和沙丘顶部4种生境类型进行实地调查,分析种群的年龄结构及其动态。运用WinDENDRO~(TM)年轮分析系统确定种群个体年龄,建立幼龄个体和成过熟个体的地径与年龄的回归方程,用以推算样地内所有个体的年龄。结果表明:滩地和沙丘底部生境下的臭柏种群10年以下幼龄植株占94%以上,其年龄结构图表现为金字塔型,属扩展种群;沙丘坡面生境下的臭柏种群以21～30年中龄植株为主,年龄结构表现为圆锥型,属稳定种群;沙丘顶部生境下的臭柏种群以51～60年成熟或老龄植株为主,年龄结构表现为倒金字塔型,属衰退种群。     

Optically stimulated luminescence dating of sandy deposits from Gulang county at the southern margin of the Tengger Desert,China

Aeolian deposits from the deserts in northern China have been used for palaeoenvironmental research to understand aeolian sedimentology and its dynamic connection to past climate conditions. The Tengger Desert in China is sensitive to the waxing and waning of the monsoonal system. In response to past climate change, the southern margin of the Tengger Desert has evolved significantly since the last glacial period. However, previous attempts to date aeolian deposits in this region were mainly based on radiocarbon dating, which has problems when applied to aeolian deposits. Moreover, sedimentary records are limited. Accordingly, past aeolian activity in this desert remains poorly understood. In the present study, we dated sand samples from Gulang county at the southern margin of the Tengger Desert using optically stimulated luminescence(OSL) to understand the history of aeolian activity in this region. Our samples represented well-sorted aeolian sands and sandy loess. Aeolian sands are evidence of dune field buildup and sparse vegetation cover whereas sandy loess is evidence of improved stabilization of sand dunes resulting from ameliorated vegetation cover. Certain samples showed a decline in the equivalent dose(De) values when successive integration intervals were applied, which resulted from unstable OSL signals from non-fast components in the initial part of the decay curve. In order to obtain reliable De estimates, we investigated component-resolved and different background subtraction approaches, and compared the resultant De estimates. We adopted the early background subtraction method to derive De values. Luminescence chronologies and sedimentary records indicated that sand dunes accumulation occurred before 10 ka, and sandy loess developed between 9.5 and 7.6 ka when sand dunes were stabilized as a result of increased effective moisture levels. The transition between sand dune mobilization and stabilization emphasizes the significance of an effective moisture threshold in controlling aeolian activity. Mobilization of sand dunes at ~2.3 ka might be related to an increased aridity during the Late Holocene.     

Aeolian transport over a developing transverse dune

The spatial and temporal changes in aeolian transport over a dune are fundamental factors that control the morphology of the dune.In the present study,we obtained direct field observations of aeolian transport over a developing transverse dune at the Shapotou Aeolian Experiment Site in the southeastern part of China’s Tengger Desert.The transport rate versus wind speed relationship is complicated over a developing dune compared with the relationships over flat surfaces and over dunes that are in equilibrium with the wind.We obtained trend lines for transport rate over the transverse dune versus distance.The transport rate generally increased from the toe to the crest above the stoss slope,but the difference in transport rate between the crest and the toe was smaller than those that have been proposed for taller dunes.The crest/toe ratio for transport rates therefore seems to depend greatly on dune height.Flux density profiles for different points above the dune at different wind speeds were well described by the exponential decay law,as has been proposed for saltation flux density profiles.Coefficients in the flux density profile function can be defined in terms of the transport rate and wind speed.However,the dependence of relative decay rate with height and average saltation height on wind speed was weaker than that observed in a wind tunnel and above a flat surface.The preliminary results obtained in this study require more evidence from field observations to fully describe aeolian transport above developing dunes.     

Wind regimes and associated sand dune types in the hinterland of the Badain Jaran Desert,China

Wind controls the formation and development of sand dunes. Therefore, understanding the wind regimes is necessary in sand dune research. In this study, we combined the wind data from 2017 to 2019 at four meteorological stations (Cherigele and Wuertabulage stations in the lake basins, and Yikeri and Sumujilin stations on the top of sand dunes) in the hinterland of the Badain Jaran Desert in China, with high resolution Google Earth images to analyze the correlation between the wind energy environments and dune morphology. The results of data analysis indicated that both the wind direction and sand drift intensity exhibited notable spatial and temporal variations. The highest level of wind activity was observed in spring. Northwesterly and northeasterly winds were the dominant in the Badain Jaran Desert. At the Cherigele, Wuertabulage, and Yikeri stations, the drift potential (DP) was below 200.00 vector units (VU). The wind energy environments in most areas could be classified as low-energy environments. The resultant drift direction differed at different stations and in different seasons, but the overall direction was mainly the southeast. The resultant drift potential (RDP)/DP ratio was greater than 0.30 in most parts of the study area, suggesting that the wind regimes mainly exhibited unimodal or bimodal characteristics. Differences between the thermodynamic properties and the unique landscape settings of lakes and sand dunes could alter the local circulation and intensify the complexity of the wind regimes. The wind regimes were weaker in the lake basins than on the top of sand dunes. Transverse dunes were the most dominant types of sand dunes in the study area, and the wind regimes at most stations were consistent with sand dune types. Wind was thus the main dynamic factor affecting the formation of sand dunes in the Badain Jaran Desert BJD. The results of this study are important for understanding the relationship between the wind regimes and aeolian landforms of the dune field in the deserts.     

西藏高原沙漠化研究中的问题和建议

西藏高原是我国沙漠化灾害严重的地区之一,近年来该区沙漠化的调查和研究得到了国内外许多学者的关注,并取得了一系列可喜的成果。文中对近年来西藏高原沙漠化研究进展进行系统的概括,并对目前高寒沙漠化研究的不足和争议进行总结,最后提出了5条建议。     

Impact of utility-scale solar photovoltaic array on the aeolian sediment transport in Hobq Desert,China

Deserts are ideal places to develop ground-mounted large-scale solar photovoltaic (PV) powerstation. Unfortunately, solar energy production, operation, and maintenance are affected bygeomorphological changes caused by surface erosion that may occur after the construction of the solar PVpower station. In order to avoid damage to a solar PV power station in sandy areas, it is necessary toinvestigate the characteristics of wind-sand movement under the interference of solar PV array. The studywas undertaken by measuring sediment transport of different wind directions above shifting dunes andthree observation sites around the PV panels in the Hobq Desert, China. The results showed that the twoparameterexponential function provides better fit for the measured flux density profiles to the near-surfaceof solar PV array. However, the saltation height of sand particles changes with the intersection anglebetween the solar PV array and wind direction exceed 45°. The sediment transport rate above shifting duneswas always the greatest, while that around the test PV panels varied accordingly to the wind direction.Moreover, the aeolian sediment transport on the solar PV array was significantly affected by wind direction.The value of sand inhibition rate ranged from 35.46% to 88.51% at different wind directions. When theintersection angle exceeds 45°, the mean value of sediment transport rate above the solar PV array reducesto 82.58% compared with the shifting dunes. The results of our study expand our understanding of theformation and evolution of aeolian geomorphology at the solar PV footprint. This will facilitate the designand control engineering plans for solar PV array in sandy areas that operate according to the wind regime.     

Coastal environment of the past millennium recorded by a coastal dune in Fujian,China

Coastal dune is a common aeolian geomorphology in a sandy coast,which records the evolution process of the aeolian landscape system and reflects the complex interaction among land surface,atmosphere and ocean.Coast is a sensitive area to global climate change.Restricted by chronology,most previous researches in China focused only on the cause of formation of coastal dunes.In recent years,the development of optically stimulated luminescence (OSL) dating provides a good method and acts as a carrier for coastal dunes to paleoclimate and paleoenvironmental studies.In this study,we selected an aeolian dune at the Anshan archaeological site,Fujian,China as the research object based on field observations.For determining their sedimentary stages and the primary influencing factors,we used the OSL dating method to construct a chronological framework for the aeolian dune.In addition,the sizes of grains were analyzed for identifying factors influencing the winter monsoon during the Medieval Warm Period (MWP) and the Little Ice Age (LIA) in this area.The results showed that the deposition of the aeolian dune was closely related to variations in the winter monsoon intensity.The changes of the winter monsoon were similar to the tendency of the East Asian winter monsoon,although there were several sub-fluctuations.From an overall perspective,the winter monsoon was strengthened during the MWP (1050–1300) .The results of a power spectrum analysis showed that the intensity of the East Asian winter monsoon is correlated with sunspot activity.     

Changes in wind activity from 1957 to 2011 and their possible influence on aeolian desertification in northern China

Wind activity is proved to have significant impacts on aeolian desertification. Clarifying the fluctuations and change trend of wind velocity is important for understanding their influence on aeolian desertification. In this study, we used a dataset of wind velocities collected from 93 meteorological stations across northern China from 1957 to 2011 to analyze the changes in wind activity during this period. We tested the monotonic and step(abrupt) trends for annual and seasonal data of mean wind velocity by using Mann-Kendall and Mann-Whitney tests, respectively. The results indicated that the annual mean wind velocity decreased by 0.83 m/s from 1957 to 2011. The decreasing trends were also significant(P<0.01) for each season. The magnitude of the decrease was smallest in the east of northern China and largest in the west of northern China, and the most remarkable decrease occurred in the northwest of northern China. Abrupt decreases in annual and seasonal mean wind velocities occurred in the mid-1980 s, which was consistent with the changes in aeolian desertification since the mid-1980 s in northern China. As revealed by our study, although both modern aeolian desertification and ecosystem rehabilitation are affected by human activities to some extent, they are also likely to be strongly controlled by climate change, especially by wind activity.     

麻扎塔格山对其南北侧风沙地貌的影响

麻扎塔格山位于塔克拉玛干沙漠腹地的和田河以西,北纬38°30′—38°40′,东经79°43′—80°48′,东西长120公里,南北宽2—4公里,高出山南平原200—300米。它的西侧是与麻扎塔格山结构、构造相似的古董山、罗斯塔格山,这一几乎连续的隆起把和田河西部的沙漠分为南北两部分。麻扎塔格山是由中上石炭系、二迭系和老第三系石灰岩、红色砂岩所组成。在该地区出露的老第三系乌拉根——卡拉塔尔组地层,中下部浅灰黄色钙质砂泥岩中夹有介壳层,含有贝氏牡蛎化石,在齐姆根组和阿尔塔什组的灰绿色泥岩、白云岩地层中含有双     

最近10年来新疆风沙地貌研究进展

最新研究表明,塔克拉玛干沙漠风沙活动与气温变化呈现"风热同步"现象,虽然其风况类型多样,但整个沙漠处于低风能环境。不同沙丘部位上风沙流输沙量的对数与高度之间表现为线性关系。当气流与沙丘走向斜交时,两侧相同部位输沙率的差异不大,这是线形沙丘保持其动力形态平衡的主要原因之一。古尔班通古特沙漠也处于复合型低能风环境之中,冬季积雪和冻土对沙漠地表形成有利的保护,有效植被覆盖和生物结皮是沙面整体处于稳定状态的重要因素,风沙活动仅存在于沙垄顶部和两坡上部。沙漠中生物结皮发育、种类丰富,其类型和分布具有明显的景观异质性特征。天山北坡和昆仑山北坡的黄土研究揭示,新疆两大沙漠从中更新世以来出现明显的干旱化,沙漠逐步扩大至今天规模。此外,塔里木沙漠公路和古尔班通古特沙漠输水明渠沿线的风沙危害具有明显的时空分异特点。因此,根据工程设施所处地形与地貌部位,可定性判断风沙危害类型与强度,进而确定防治方案和措施。今后新疆风沙地貌学研究应注重研究领域的拓展、研究方法的突破和实验手段的创新3个方面。     

塔克拉玛干沙漠腹地复合纵向沙垄间地沙丘空间分形及稳定性

塔克拉玛干沙漠的大地貌格局是高大复合沙垄和宽广垄间地相间分布,而垄间地是研究简单沙丘发育过程的良好试验场地。基于Google Earth影像,以分形理论为基础,对塔克拉玛干沙漠腹地复合纵向沙垄区垄间地上覆沙丘在主导风方向上的分形特征进行了分析,结果表明：① 垄间地沙丘形状指数（面积-周长关系）的标度-频度双对数关系非常显著,分形关系客观存在,并且不受统计时所用标度的影响;② 垄间地各类沙丘的分维值存在差异,其中,饼状沙堆和沙片分维值最大（1.337）,新月形沙丘次之（1.170）,简单线性沙丘最小（1.087）;③ 垄间地沙丘分维值的空间差异较大,在1.187~1.656,其分维数：背风坡脚（1.24）＜垄间地中部（1.40）＜迎风坡脚（1.50）,变异系数为0.106;④ 垄间地沙丘稳定性指数与分维值的空间分布相反,即背风坡脚（0.26）＞垄间地中部（0.16）＞迎风坡脚（0.10）;⑤ 垄间地沙丘分维值空间差异主要与沙丘发育程度有关,其中,风信是动力基础,沙源是物质基础。在流动沙漠,沙丘分形维数可以作为反映其风沙环境特征的定量指标。