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1. chinaXiv:201910.00004 [pdf]

库布齐沙漠生态光伏电站风速脉动特征

杨世荣
Subjects: Geosciences >> Geography

研究沙区光伏电板扰动下风速脉动特征,掌握光伏电站风蚀沙埋规律。本文选取生态光伏电站内2个断面,对电板阵列板下、板前以及板间等典型部位20、50、80、100、200 cm的5个高度风速进行测定,分析了光伏电站的风速流场、脉动特征。研究结果表明:① 光伏电板上风向边缘风速呈最大,经过阵列逐渐减弱,光伏电场阵列腹部风速明显降低,尤其在近地表层,相比电板阵列腹部平均风速,板下、板前、板间20 cm平均风速增加了44.7%、54.8%和7.2%。;② 光伏电板上风向3处位置风速脉动、风速脉动强度强度表现为随高度增加呈先降低后增加趋势,腹部电板随高度的增加呈降低趋势,其中20~80 cm范围湍流度最为为剧烈;与对照相比,光伏电板上风向边缘处湍流度在板下、板前位置随高度呈增强趋势。③ 光伏电板周围的风速脉动是形成板下和板前涡流的主要动力,进而造成光伏基座掏蚀与板间积沙带的发育。

submitted time 2019-10-11 From cooperative journals:《干旱区研究》 Hits4792Downloads131 Comment 0

2. chinaXiv:201910.00005 [pdf]

陕北六道沟流域切沟形态复杂性及其类型划分

赵影
Subjects: Geosciences >> Geography

黄土高原切沟对流域地貌和自然环境造成了深刻影响,研究切沟形态特征有助于揭示其发育过程和演化机理。在陕北六道沟小流域,利用手持GPS测量32条发育典型的切沟,通过研究取得以下结果:① 沟长大于100 m的切沟占调查总数的81.2%。切沟横向扩张程度大于其下切程度,且宽度和深度自沟头和横断面到沟口显著增加(P < 0.05);② 与形状指数相比,计盒维数对切沟分支和边缘破碎信息表达效果更佳;③ 根据切沟分支情况,其形态可分为线型、沟头扩展型、沟头分支型和沟底分支型4种类型。总之,从主沟和支沟的空间联系、支沟沟长占比和对切沟类型划分而言,支沟是重新认识切沟和流域破碎地貌不可忽视的重要组成部分。

submitted time 2019-10-11 From cooperative journals:《干旱区研究》 Hits5029Downloads101 Comment 0

3. chinaXiv:201910.00007 [pdf]

基于FLUS模型的天山山区未来土地利用变化预估

秦埼瑞
Subjects: Geosciences >> Geography

基于天山山区53个气象站点,31个CMIP5全球气候模式,集合逐年平均气候资料、社会经济和自然地形等资料,利用FLUS模型,预估了2050年RCP2.6、RCP4.5和RCP8.5排放情景下天山山区土地利用变化。结果表明:① FLUS模型能够较好地模拟研究区历史土地利用变化,具有较高的模拟精度。② 与基准期(1970—1999年)相比,3种情景下多年平均气温升高了1.67~2.16 ℃,其中春季和夏季增温幅度较小,秋季和冬季增温幅度较大。多年平均降水量增加22~25 mm,3种情景下个别年份较基准期出现降水减少现象,但总体呈增加趋势。③ 2050年RCP2.6、RCP4.5和RCP8.5的预估结果与2017年实测土地利用结果相比,天山山区冰雪面积分别减少29.2%、34.6%、38.4%。前2种情景城市用地面积增幅不大,部分耕地转换为城市用地和草地,林地面积少量增加。而RCP8.5情景下城市用地面积为2017年的近3倍,部分林地转换为草地。3种情景下水体总面积略有增加,未利用地呈减少趋势。

submitted time 2019-10-11 From cooperative journals:《干旱区研究》 Hits4582Downloads114 Comment 0

4. chinaXiv:201910.00016 [pdf]

新疆南部矮化红枣树干液流特征及其对环境因子的响应

刘毅
Subjects: Geosciences >> Geography

应用FLGS-TDP插针式热扩散探针技术,对策勒绿洲的矮化红枣树干液流进行长期监测,同步记录试验地周围的气象因子,分析矮化红枣树干液流变化规律,建立树干液流与环境因子之间的关系模型。结果表明:液流日变化呈单峰曲线,夏季偶尔会出现双峰曲线;天气条件对液流变化有影响,晴天条件下的液流速率最大,沙尘天气次之,雨天液流速率最低;不同季节间的液流速率差异显著,夏季液流启动于6:30左右,比春季和秋季的液流启动时间早;夏季树干液流持续时间最长,春季和秋季液流持续时间相对较短,夏季液流速率峰值最高,春季和秋季峰值偏低;生长期内液流速率与太阳辐射强度、大气温度呈显著正相关关系,与空气相对湿度呈显著负相关关系;各种环境因子中太阳辐射强度对液流速率的影响最大,相关系数为0.927,其次是大气温度,相关系数为0.725 4,空气相对湿度的影响最小,其相关系数为0.548。通过对矮化红枣树干液流进行监测,研究分析矮化红枣的水分消耗特征,为绿洲农业水资源分配管理提供数据支撑。

submitted time 2019-10-11 From cooperative journals:《干旱区研究》 Hits4181Downloads87 Comment 0

5. chinaXiv:201910.00022 [pdf]

新疆策勒绿洲—沙漠过渡带不同下垫面风场特征

毛东雷
Subjects: Geosciences >> Geography

以新疆策勒2010年8月至2011年7月的气象数据为依据,运用数理统计方法,对策勒绿洲—沙漠过渡带流沙地、半固定沙地、固定沙地及绿洲内部4个下垫面的风况进行统计分析,为风场的时空差异特征和植被防风阻沙效益研究提供理论依据。结果表明: 研究区4个下垫面主风向以 WNW、W为主,所占频率分别为 41.43%、33.74%。从流沙地、半固定沙地、固定沙地到绿洲内部,静风所占的频率依次为44.30%、52.44%、54.29%和85.39%,随着风速的增大,其所占频率依次减小,气温与风速均呈现同步变化的趋势。较高起沙风频率与起沙风月平均最大风速多出现在春、夏两季,6月份频率最大,虽然最大值出现月份不同,但变化趋势相似。从绿洲外围向绿洲内部风向不同,且主风向所占频率减少,表明植被能削减风速并使风向变得更加分散。平均风速、起沙风频率从流沙地到绿洲内部逐渐减小(少)。月平均风、温之间成显著相关性,且从流沙地前缘到绿洲内部相关性逐渐减弱。植被类型、植被覆盖度和地形等是影响不同下垫面风场特征的主要因素。

submitted time 2019-10-11 From cooperative journals:《干旱区研究》 Hits2856Downloads88 Comment 0

6. chinaXiv:201904.00091 [pdf]

Dynamics of infiltration rate and Field-Saturated soil hydraulic conductivity in a Wastewater-Irrigated cropland

Siyi Zhang; Isaac Hopkins; Li Guo; Henry Lin
Subjects: Geosciences >> Geography

The maintenance of a soil’s infiltration rate (IR) and field-saturated hydraulic conductivity (Kfs) is crucial for the long-term sustainable functioning of wastewater-irrigated lands. However, an effective procedure for reliably measuring in situ soil Kfs remains elusive. To address this issue, this study investigated the DualHead Infiltrometer (DHI), a novel instrument for automatically determining IR and Kfs, and compared it with a traditional Double-Ring Infiltrometer (DRI) under various field conditions. In the initial phase, we optimized the procedure and settings for the DHIs in a cropland that has been spray-irrigated with secondary-treated wastewater for decades in central Pennsylvania. Results showed that our optimized procedure, which used a single, long pressure cycle, yielded more robust measurements of IR than the originally recommended sequence of two short pressure cycles. The values of Kfs measured by the DHIs with optimized settings were similar to those measured by DRIs under many (but not all) field conditions, due to their differences in infiltration surface areas, operational procedures, length of infiltration time, and soil spatiotemporal variability. Viscosity-corrected Kfs on the irrigated cropland was 123.8±94.0 mm h-1, higher than that on the adjacent non-irrigated cropland (103.2±94.6 mm h-1), but the difference was not statistically significant, owing to the high degree of soil spatiotemporal variability and our limited number of measurements. Nevertheless, the higher Kfs values measured on irrigated cropland reflect observed changes in soil structure (e.g., soil pore characteristics) that have resulted from decades of irrigation. Seasonal variations in Kfs values existed between winter and summer conditions, but IRs during all seasons remained much higher than the current spray-irrigation rate (4.25 mm h-1), suggesting that the soil is still capable of handling the routine irrigation, even during winter. However, the coefficients of variation exceeded 67.0% across the field sites investigated and the time periods covered by our measurements were limited. As this specific site is permitted to discharge treated wastewater year-round, caution must still be exercised to ensure that soil Kfs remains high enough to prevent runoff generation, especially during winter frozen conditions.

submitted time 2019-09-06 Hits15586Downloads1191 Comment 0

7. chinaXiv:201909.00017 [pdf]

基于建设开发适宜性评价的干旱区绿洲城市增长边界的划定 —以乌鲁木齐市为例

朱天翥
Subjects: Geosciences >> Geography

科学合理地划定城市增长边界是控制城市无序蔓延、减少土地利用效率低下的有效途径,也是目前我国空间规划探索的重要内容之一。城市增长边界划定应依据区域不同资源环境本底条件和建设开发水平,因地制宜地选择合适的指标和方法,才能更准确地反映出城市发展的实际和需求,起到切实的指导作用。干旱区城市的发展受绿洲-荒漠生态系统影响作用显著,城市扩张过程中人地矛盾较为突出,城市增长边界划定必须体现资源环境-经济社会发展的协调性。本文以乌鲁木齐市为例,基于资源环境底线和城市发展潜力评价相叠加的研究思路,尝试探索干旱区绿洲城市增长边界划定的可行方法,结果表明:① 限制性评价和适宜性评价相结合的方法,可以很好地划定干旱区绿洲城市增长边界;② 将绿洲区域作为土地潜力的评价单元,对于干旱区绿洲城市划定城市增长边界更加合理和适用;③ 城市增长边界划分为刚性边界和阶段性边界可以指导城市土地的开发。

submitted time 2019-09-05 From cooperative journals:《干旱区研究》 Hits2901Downloads73 Comment 0

8. chinaXiv:201909.00019 [pdf]

基于FLUS模型的天山山区未来土地利用变化预估

秦埼瑞
Subjects: Geosciences >> Geography

基于天山山区53个气象站点,31个CMIP5全球气候模式,集合逐年平均气候资料、社会经济和自然地形等资料,利用FLUS模型,预估了2050年RCP2.6、RCP4.5和RCP8.5排放情景下天山山区土地利用变化。结果表明:① FLUS模型能够较好地模拟研究区历史土地利用变化,具有较高的模拟精度。② 与基准期(1970—1999年)相比,3种情景下多年平均气温升高了1.67~2.16 ℃,其中春季和夏季增温幅度较小,秋季和冬季增温幅度较大。多年平均降水量增加22~25 mm,3种情景下个别年份较基准期出现降水减少现象,但总体呈增加趋势。③ 2050年RCP2.6、RCP4.5和RCP8.5的预估结果与2017年实测土地利用结果相比,天山山区冰雪面积分别减少29.2%、34.6%、38.4%。前2种情景城市用地面积增幅不大,部分耕地转换为城市用地和草地,林地面积少量增加。而RCP8.5情景下城市用地面积为2017年的近3倍,部分林地转换为草地。3种情景下水体总面积略有增加,未利用地呈减少趋势。

submitted time 2019-09-05 From cooperative journals:《干旱区研究》 Hits2278Downloads80 Comment 0

9. chinaXiv:201909.00004 [pdf]

全新世以来青藏高原文化遗址时空演变及其驱动

金孙梅
Subjects: Geosciences >> Geography

青藏高原是全球地理环境最为特殊的区域之一,研究全新世以来青藏高原文化遗址时空演变及其原因,对于理解极端环境下的人类响应与适应具有重要意义。基于ArcGIS空间分析,运用核密度估计、平均最邻近指数和全局空间自相关等地理统计方法,研究了全新世以来青藏高原14 339处文化遗址的时空演变。结果表明:各时期遗址最近邻指数均小于1,全局Moran’s I的取值介于0~1之间,遗址存在正的空间自相关,且属于集聚分布的模式;遗址分布重心经历了由高原腹地(旧石器时期)—东南边缘谷地(新石器时期)—东部地域(青铜器时期以来)的转变;遗址分布形态特征则经历了均匀广布型(旧石器时期)、边缘河谷型(新石器时期)、河谷集聚型(青铜器时期)、退化分散型(吐蕃部落时期)、半月广布型(吐蕃王朝时期)、斑块广布型(元代)、连片集聚型(明清时期)的变化过程;青藏高原各时期遗址时空分布演变是海拔、气候变化、植被等自然环境,以及生产方式、技术、战争、人口迁移、政治政策等社会经济因素共同作用的结果。

submitted time 2019-09-02 From cooperative journals:《干旱区研究》 Hits1779Downloads93 Comment 0

10. chinaXiv:201909.00005 [pdf]

A drought resistance index to select drought resistant plant species based on leaf water potential measurements

SayedJamaleddin KHAJEDDIN
Subjects: Geosciences >> Geography

The water deficit in arid and semi-arid regions is the primary limiting factor for the development of urban greenery and forestation. In addition, planting the species that consume low levels of water is useful in arid and semi-arid regions that have poor water management measures. Leaf water potential (Ψ) is a physiological parameter that can be used to identify drought resistance in various species. Indeed, Ψ is one of the most important properties of a plant that can be measured using a pressure chamber. Drought avoiding or drought resistant species have a lower Ψ than plants that use normal or high levels of water. To determine drought resistance of species that are suitable for afforestation in arid urban regions, we evaluated twenty woody species in the Isfahan City, central Iran. The experimental design was random split-split plots with five replications. The species were planted outdoor in plastic pots and then subjected to treatments that consisted of two soil types and five drip irrigation regimes. To evaluate the resistance of each species to drought, we used the Ψ and the number of survived plants to obtain the drought resistance index (DRI). Then, cluster analysis, dendrogram, and similarity index were used to group the species using DRI. Result indicates that the evaluated species were classified into five groups: (1) high water consuming species (DRI>–60 MPa); (2) above normal water consuming species (–60 MPa≥DRI>–90 MPa); (3) normal water consuming species (–90 MPa≥DRI>–120 MPa); (4) semi-drought resistant species (–120 MPa≥DRI>–150 MPa); and (5) drought resistant species (DRI≤–150 MPa). According to the DRI, Salix babylonica L., Populus alba L., and P. nigra L. are high water consuming species, Platanus orientalis L. and Albizia julibrissin Benth are normal water consuming species, and Quercus infectoria Oliv. and Olea europaea L. can be considered as drought resistant species.

submitted time 2019-08-30 From cooperative journals:《Journal of Arid Land》 Hits2845Downloads92 Comment 0

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