共查询到19条相似文献，搜索用时 171 毫秒
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干旱区绿洲空间分异演化研究--以黑河流域绿洲为例 总被引：7，自引：5，他引：7
对干旱区绿洲的物质和能量空间分异现象和规律的研究,有助于深刻了解不同类型绿洲形成和演化的自然背景和农业资源组合的特点,为农业生产的合理布局和农业自然资源的优化配置提供理论依据. 以黑河流域绿洲为例,在综合分析影响绿洲空间分异的气候、地质构造和地貌演化、地表水和地下水水文化学性质、土壤性状和水资源供应状况等自然地理要素基础上,将黑河绿洲划分为高位绿洲、中位绿洲和低位绿洲等不同类型. 在此基础上,分析了黑河流域不同类型绿洲主要农作物气候适宜性的空间分异,为绿洲农业资源的优化配置提供了重要的理论依据. 相似文献
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在我国西北干旱和半干旱地区, 农业收获主要依靠灌溉保证, 灌溉绿洲的蒸散发(ET)是当地水资源的主要消耗. 通过遥感估算区域灌溉绿洲的ET对于地区合理利用水资源极其重要, 利用MODIS/Terra 影像, 基于物理过程的地表能量平衡模型(SEBS), 结合WRF模式输出的气候驱动数据和地面观测数据来估算黑河中游地区的地表通量和日蒸散发(ETdaily). 估算的ET用不同下垫面的涡动相关仪观测数据进行验证, 结果显示: SEBS模型估算的不同下垫面的ETdaily具有很好的拟合效果(R2=0.96, P<0.001), 在灌溉绿洲估算的ETdaily比实测值偏高, 说明干旱、半干旱地区灌溉绿洲土壤水分胁迫是影响ET的主要因素. 模型估算绿洲作物生长期间的ETdaily和实测的ETdaily平均相对误差为12.5%, 精度在观测的能量不闭合误差以内且精度比戈壁和沙漠地区高. 相似文献
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绿洲是干旱区最重要的景观类型,由于气候干旱、水资源贫乏,系统往往具有生态脆弱性质。作者通过对黑河流域的野外考察和分析认为,人类活动在干旱区绿洲地区环境退化中起重要作用。黑河发源于祁连山,全长821km,干流穿过河西走廊,向北注人居延海。流域位于河西走廊中段,由三个景观单元组成：1）上游祁连山区,由山地森林、灌丛和草地景观构成;2）中游走廊地区,以平原绿洲景观为主;3）下游金塔盆地及阿拉善高原,以高平原荒漠景观为主,沙漠、戈壁广布,有小面积绿洲分布。黑河原属外流河,中更新世晚期以来水量逐渐减少,变为内陆河… 相似文献
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黑河中游间作灌溉农田的能量平衡 总被引：2，自引：0，他引：2
利用布设在黑河流域中游的张掖绿洲区的一套自动气象观测系统在2004年作物生长期内的完整资料,分析了黑河中游春小麦和玉米间作农田生态系统的辐射收支,在此基础上选用波文比能量平衡法(BREB)进行了能量平衡计算.结果表明:间作作物-土壤系统截获的太阳短波辐射占太阳总辐射的比例从生长初期的0.81持续增加到生长末期的0.86;净辐射在生长初期较小,生长中期第一阶段增幅大,至第二阶段达到最大,生长末期降低;净辐射占太阳总辐射的比例与净辐射的变化相似.能量平衡中,净辐射的消耗以潜热为主,占70%左右,感热能量占20%,土壤热通量占净辐射总值的10%.不同生长阶段的能量平衡差异较大,能量平衡在不同生长阶段呈现出不同的日变化特征. 相似文献
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关于拯救额济纳绿洲的紧急建议 总被引：8，自引：1，他引：8
关于拯救额济纳绿洲的紧急建议中国科学院地学部１９９５年８月２３日～９月４日，由７名中国科学院院士和５位特邀专家组成考察团，对黑河中、下游进行了专题考察，亲眼目睹了额济纳绿洲生态环境严重恶化，已濒于消亡的危急状况。黑河下游是额济纳绿洲以荒漠河岸林为主的... 相似文献
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黄河上游夏季晴天地表辐射和能量平衡及小气候特征 总被引：7，自引：2，他引：5
利用2005年7月17日-8月9日玛曲地气相互作用预实验观测资料, 从中选取了5个资料完整的连续晴好天气, 分析了黄河上游高寒草甸地区夏季小气候、 地表辐射和能量平衡连续日变化特征. 结果表明: 在晴好天气条件下这一地区近地层动量湍流通量受风速切变控制;总辐射峰值与青藏高原北部相比略小, 但比干旱半干旱区的敦煌要大;地表反照率平均值为0.17, 介于河西金塔绿洲农田与沙漠观测的结果之间;能量平衡中潜热释放比感热输送显著的多;观测中也发现有较大的能量不平衡差额. 获得了对这一地区夏季地表辐射、能量、反照率、能量闭合度和小气候特征的一些新认识, 为今后在这一地区进一步开展深入研究提供借鉴. 相似文献
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沙漠—绿洲过渡带近地表风沙过程研究进展 总被引：1，自引：0，他引：1
受绿洲和沙漠景观格局的双重影响,沙漠—绿洲过渡带是一个对外界条件变化极为敏感的生态环境脆弱带。沙漠—绿洲过渡带近地表风沙过程及其动态演变直接影响绿洲的稳定和有序发展,在空间上制约沙漠的进退或绿洲的变迁。从沙漠—绿洲过渡带局地小气候、沙尘暴、风沙环境、土壤风蚀、风沙输移和绿洲防护体系建设等几个方面比较全面地综述了近数十年来沙漠—绿洲过渡带近地表风沙过程研究进展,并基于当前沙漠—绿洲过渡带生态环境建设与地方需要等面临的实际问题,分析了该领域今后的研究重点和发展趋势。 相似文献
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中国西北地区额济纳绿洲植被盖度与黑河流量的滞后效应研究 总被引：6，自引：1，他引：5
干旱区植被生长与地下水的关系是生态水文地质学研究的热点之一。西北干旱地区,由于降水稀少,绿洲是当地人类生存和发展的主要依托。近年来,随着黑河流域中游地区用水量的逐年加大,下游来水量减少,使得下游额济纳绿洲的面积不断减小,湖泊干涸,沙漠化严重,生态环境恶化。由于绿洲植被的生长与水有极为密切的关系,因此,研究河流流量与绿洲植被生长之间的定量关系,对改善黑河流域生态环境、协调用水矛盾和合理配置水资源具有重要意义。将遥感数据与黑河径流量数据相结合,在区域尺度上定量研究额济纳绿洲植被生长与河流径流量的关系。结果表明,绿洲植被对黑河径流以及地下水有很强的依赖关系,而且黑河径流对额济纳绿洲的影响存在一年的滞后期,而地下水则通过这种滞后作用将两者联系起来。 相似文献
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黑河实验(HEIFE)能量平衡和水汽输送研究进展 总被引：7，自引：1，他引：7
It is a review about advance of research on energy budget and transportation of water vapour in the HEIFE area. A basic model, the cold island in oasis and the inverse humidity phenomenon in desert, about interaction of oasis with desert environment is established. The major disturbance of the oasis to observation in the desert is the latent heat flux that is an ignored value in the energy budget on ground surface in the desert. Consequently, it is representative of the arid region to have measured energy budget at the gobi station and desert station in the HEIFE area. 相似文献
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Xihu desert wetland is an important and unusual environment in China or even in the world. However, until now, little research has been focused on the microclimate and CO2 flux characteristics in this area. This paper reports the characteristics of daily variations of microclimate and CO2 flux in the Dunhuang Xihu desert wetland, based on data observed in the desert wetland during a period of continuous fine weather in summer 2012. Results indicate that the characteristics of the micrometeorology were significantly affected by the land–lake breeze during the study period, and updrafts were prevalent in this region. The friction wind speed and the vertical velocity were much greater than those in the Maqu grasslands. The energy budget was strongly imbalanced: the latent heat flux was significantly higher than the sensible flux. The daily mean values of total solar radiation and net radiation were larger than those in Maqu grasslands and Jinta oasis. There was a temperature inversion and inverse humidity gradient in the atmospheric surface layer at night. The desert wetland ecosystem was a carbon sink during the whole of the observation period, and the maximum rate of carbon absorption usually occurred at about 11:00 hr each day in this region. 相似文献
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对中国天山北坡三工河流域山地、绿洲、荒漠不同下垫面区域1961-2007年气象资料序列进行了分析, 结果表明: 近50 a平原绿洲区平均温度以0.3 ℃·(10a)~(-1) 趋势上升;流域山区增温趋势较慢, 平均每10 a以0.17 ℃的趋势增温, 但本世纪初增温速率加快, 绿洲区和山区分别增加0.7 ℃和 0.5 ℃. 流域CO_2浓度和CH_4浓度持续上升, 且高于全球平均水平.原绿洲区1987-2007年比1961-1986年平均降水量偏多35%;山区降水量平均每10 a增加速率和绿洲区基本一致, 但波动较大, 20世纪80年代降水增加较显著, 90年代降水量减少到70年代水平, 本世纪初降水量显著增加. 气候变化序列用Mann-Kendall方法检验认为, 山区温度和降水没有达到突变水平, 平原绿洲区降水在1984年发生了由低向高的突变, 温度在1995年发生了由低向高的突变. 夏季荒漠空气相对湿度、太阳辐射量均小于绿洲, 但温度却始终高于绿洲, 绿洲"湿岛效应"和"冷岛效应"特征明显. 荒漠-绿洲温差有3 h、 20 h的主要周期, 温差突变一般发生在凌晨. 相似文献
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The purpose of this study is to investigate the oasis landscape fragmentation in northwestern China’s arid regions. Landscape
maps of Jinta oasis were compiled by using GIS based on Landsat TM data of 1990 and 2000. Landscape indexes for evaluating
fragmentation are patch area, patch density, corridor density and split index. Results indicated many difference. First, between
the years 1990 and 2000, the landscape fragmentation in Jinta oasis decreased slightly. Second, the area of the matrix decreased
at the class level. The landscape fragmentation of the matrix (bare soil) increased as a result of increased influence of
human activities on matrix and was opposite to the irrigated farmland whose area is larger and more aggregated in 2000 than
in 1990. Third, dense corridor system is one of the most prominent characteristics of the arid regions. It is one of the key
factors resulting in the landscape fragmentation; especially the fragmentation within the same patch types. The corridor density
of irrigated farmland, residential area and forestland were quite large in Jinta oasis both in 1990 and 2000. The pattern
of Jinta oasis is characterized by agricultural oasis embedded in Gobi and in the desert, where the ecosystem was disturbed
strongly by the intense human activities. 相似文献
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Ming Zhao Ke Jie Zhan Guo Yu Qiu Er Tian Fang Zi Hui Yang Yin Chang Zhang Ai De Li 《Environmental Earth Sciences》2011,62(2):403-410
The height profile of sand-dust flux at 0–2.0-m has been well studied. However, there have been very few experimental studies
in the 0–50-m layer. In this study, the height profile of sand-dust flux at 0–50-m was observed by using three sandstorm observation
towers (50 m in height) in 2006. The towers were located at three sites with different vegetation conditions (desert, edge
of an oasis, and oasis) in the Minqin region, a typical desert-oasis area in China. At the same time, the features of the
underlying vegetation were investigated. Results indicated that in the 0–50-m layer, sand-dust flux decreased rapidly as height
rose at the desert and the edge of oasis sites, whereas it increased slightly as height rose in the oasis site. At the three
sites sand-dust fluxes at each height increased with wind velocity, and there was a fairly good exponential relationship among
them. In 2006, a total of 19 sandstorms occurred. The annual sand-dust that passed through a 1-m-wide, 50-m-high section was
9,169 kg at the desert site, 5,318 kg at the edge of oasis site, and 2,345 kg at the oasis site. Compared with the desert
site, the annual sand flux was lower by 42% at the edge of oasis site and 74% at the oasis site. Vegetation had a significant
effect in reducing the sand-dust flux. 相似文献
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绿洲地理特征及其气候效应 总被引：43，自引：4，他引：43
根据绿洲的一些共性给出了绿洲的科学定义。并且根据以往大量研究成果,系统地归纳了世界上绿洲分布的区域类型、形成的客观条件、需要的水文环境、植被和土壤类型及其分类等地理特征,全面总结了绿洲"冷岛"结构、"冷岛"效应、"湿岛"结构、临近荒漠逆湿、高额可利用能量、风屏作用、动力和热力效应、增雨作用等主要气候效应。在此基础上,提出了绿洲具有系统性、对水的依赖性、高比照性、尺度性、高效性、脆弱性、演化性等本质特性。最后还讨论了人类活动对绿洲的作用和影响。 相似文献
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Desert–oasis ecotone is an interactive area between desert and oasis ecosystems which plays an important role in ensuring
oasis ecological security and maintaining oasis internal stabilization. The studied region had experienced dramatic landscape
change and soil degradation during the 20th century, especially in the last two decades. To document the status and evaluate
this degradation process, geostatistics and GIS map algebra were used to quantify the temporal–spatial changes in landscape
pattern and soil degradation from 1983 to 2005. The results showed that: (1) the change of landscape pattern due to human
activities was the key reason responsible for the increasing of landscape diversity and fragmentation; (2) the extent of soil
degradation was higher near desert ecosystem than oasis, and human activities were the major driving forces in ameliorating
the soil properties; and (3) soil degradation is weaker in regions of bad soil quality than regions of good soil quality due
to both human activities and natural processes. 相似文献
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黑河流域中游张掖绿洲景观格局研究 总被引：35，自引：2，他引：33
在解译的张掖绿洲土地利用/土地覆盖图的基础上, 进行相关的景观类型综合处理, 计算了绿洲景观格局的多个指数. 结果表明, 绿洲景观的组成以戈壁、沙地、耕地和草地为主, 体现了荒漠基质受人工影响而形成的典型农业型绿洲的特点. 绿洲内居民点众多, 仅与少数类型邻接并且比较分散, 戈壁、平原旱地和沙地分布则比较集中. 盐碱地和裸岩石砾地的形状最复杂, 戈壁的形状则最简单; 同时, 平原旱地、戈壁和裸岩石砾地的连接性均较好, 在景观中占有较大比重, 类型间的物质和能量迁移比较通畅. 相似文献