Influence of shrub canopy morphology and rainfall characteristics on stemflow within a revegetated sand dune in the Tengger Desert,NW China   总被引：1，自引：0，他引：1  

Xin‐ping Wang  Ya‐feng Zhang  Zheng‐ning Wang  Yan‐xia Pan  Rui Hu  Xiao‐jun Li  Hao Zhang 《水文研究》2013,27(10):1501-1509

Stemflow of xerophytic shrubs was monitored on event basis within a revegetated sand dune. Quantity of stemflow showed a clear species‐specific dependence in combination with the rainfall characteristics. Results obtained revealed that for ovate‐leaved C. korshinskii with an inverted cone‐shaped canopy and smooth bark, the quantity of stemflow in depth accounted for 7.2% of the individual gross rainfall, while it was 2.0% for needle‐leaved A. ordosica with a cone‐shaped canopy and coarse bark. There were significant positive linear relationships between stemflow and individual gross rainfall and rainfall intensity for the two shrubs. An individual gross rainfall of 1.4 and 1.8 mm was necessary for stemflow generation for C. korshinskii and A. ordosica, respectively. Multiple regression analysis showed that the abiotic and biotic variables including the individual gross rainfall, mean windspeed (WS), canopy height, branch length, and canopy volume have significant influence on stemflow for C. korshinskii, whereas for A. ordosica, the notable influencing variables were individual gross rainfall, stem diameter, and leaf area index. Generally, WS has less effect on stemflow than that of rainfall for A. ordosica. The correlation relationship between individual gross rainfall and funneling ratio showed that the funneling ratio attains its peak when the gross rainfall is 13 and 16 mm for C. korshinskii and A. ordosica, respectively, implying that the canopy morphology emerged as determining factors on funneling ratio decrease when the individual gross rainfall exceeds these values. In comparison, higher WS increased the funneling ratio remarkably for C. korshinskii than A. ordosica due partly to the greater branch length and canopy projection area in C. korshinskii. Funneling ratio can be used as an integrated variable for the effects of canopy morphology and rainfall characteristics on stemflow. The implication of stemflow on water balance and its contribution to sustain the shrubs and the revegetation efforts was discussed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

钢筋混凝土柱的破坏形态及变形能力研究     

刘科  黄娇  马煜东  张宁  苏佶智 《震灾防御技术》2019,14(4):750-759

对钢筋混凝土（RC）柱在地震作用下的变形性能进行量化,本文从太平洋地震研究中心柱数据库中收集到123根RC柱抗震性能试验数据,提出基于参数剪跨比和弯剪比的RC柱破坏形态判别标准;在弯曲破坏、弯剪破坏、剪切破坏三种破坏形态下,研究了轴压比、剪跨比、配箍特征值等参数对位移角的显著性影响,通过回归分析归纳出三种破坏形态下屈服位移角和极限位移角的回归方程,回归系数显著性概率均小于0.05。结果表明:本文提出的RC柱破坏形态判别标准准确度高,适应性强;位移角线性回归方程具有合理性。  相似文献   

软土地基三维粘弹性反演分析与变形预测研究   总被引：1，自引：1，他引：0  

何跃平  朱合华  付艳斌  庄宁 《上海国土资源》2005,(2):16-18,23

针对无锡地区软土工程施工具有明显流变性的特点,运用粘弹性理论和反演分析方法,结合无锡市图书馆工程对其地基变形和粘弹性模型进行了研究,通过实测数据与计算值的对比来修正模型和计算参数;在此基础上对该工程的长期地基沉降进行了预测,取得了与实际较为吻合的结果,为本地区软土工程地基的长期变形预测提供了有效的方法和思路。  相似文献   

湖南大龙洞流域不同岩性不同土地利用类型条件下碳酸盐岩试片的溶蚀速率   总被引：4，自引：2，他引：2  

王文娟  蓝芙宁  蒋忠诚  覃小群  劳文科 《中国岩溶》2013,32(1):29-33

选择湖南大龙洞流域寒武系中统熬溪组上段(∈2a3)白云岩、寒武系上统比条组下段(∈3b1)和奥陶系中统牯牛潭组(O2g)灰岩进行野外溶蚀试验,并测试林地和草地类型土壤剖面20cm、50cm深度土壤CO2浓度和有机质含量,以探讨林地、草地土地利用类型条件下试片溶蚀速率的差异特征。结果表明:(1)O2g、∈3b1和∈2a33种试片溶蚀速率在林地和草地土下20cm、50cm深度差异明显,∈3b1g灰岩林地土下20cm试片的溶蚀速率最大,达357.93mg/(m2?d);(2)试片溶蚀速率受岩性影响明显,CaO含量高,溶蚀速率大,O2g、∈3b1灰岩中CaO含量分别为35.38%、47.45%,较∈2a3白云岩的含量32.64%高,因而其溶蚀速率也较∈2a3的大;(3)埋放于林地土壤的试片其溶蚀速率大于草地,表明土地类型对溶蚀速率有较大的影响,植被从草地向林地的正向演替有利于岩溶作用的进行。   相似文献   

海底取样器工作机理分析及选用原则——海底取样技术专题之二          下载免费PDF全文

鄢泰宁  昌志军  补家武 《探矿工程》2001,(3):19-22

分析了海底取样过程的“桩效应”问题，阐述了振动取样器贯入沉积物的原理，归纳了取样器的选用原则，并就完海底取样技术提出了建议。  相似文献   

西北地质调查工作特点及其发展对策思考     

李文渊  徐学义  赵东宏  申少宁  张百志 《西北地质》2002,35(4):1-8

资源与环境是当今人类社会最为关注的两大热点问题，而地质学是贯穿于这两大主题的基础。西北地区地处大陆腹地，独特的地理位置、特殊的地质环境和长期的地质作用历史，形成了以中亚成矿特色为主的丰富的矿产资源。由于人类历史以来深居内陆的环境特点，并且随着人类活动的加剧日益造成了干旱一半干旱的缺水环境。开发大西北，矿产资源的有效发现和合理利用，以及对人类活动诱发或加剧的地质灾害的科学认识与防治，是新时期地质工作更加关注和拓宽的历史任务。实施地质大调查以来，西北地质调查工作全方位取得了新的进展，并展示了愈来愈广阔的应用天地。本文在回顾已有地质调查成果的基础上，对其发展对策提出初步思考，提出经济－地质关联概念，意在西北地区经济活动背景下，探讨地质调查工作的作用和发展方向。  相似文献   

基于数据仓库的空间可持续发展决策支持技术研究--以东莞市耕地变化研究为例     

钱峻屏  叶树宁  李岩 《热带地理》2002,22(2):176-180

以决策支持理论为指导，以遥感和信息系统为技术手段，构造基于数据仓库技术的耕地决策支持系统，以实现多源空间数据的集成、分析、模拟和决策，并以东莞市耕地可持续利用动态研究为例，完成了基于可持续发展研究的因子筛选、模型构建和基于数据仓库的决策分析，探讨了数据仓库技术在空间定量决策分析中的应用，为区域可持续发展研究进行了有益的实践。  相似文献   

吉林玉米带的地位与发展前景   总被引：16，自引：1，他引：16  

齐晓宁  王洋  王其存  刘兆永  鲍强 《地理科学》2002,22(3):379-384

对我国玉米生产概况和玉米在我国粮食生产中的地位作了概述，重点论述了吉林玉米带以玉米为主的粮食生产结构带来的问题。一方面，生产量大于需求量，加工形式单一，玉米积压严重，另一方面，由于生态成本高，比较效益低，作为农民家庭的主要经营收入低，限制了农民种植玉米的积极性，同时地方财政为保证保护价收购玉米而背上沉重包袱。加入WTO后，这些问题必将对吉林省玉米生产产生巨大影响。因此，提出了5条改善措施；即；科学规划，适当压缩玉米生产面积，建立优质玉米生产基地，以提高单产而保证增加总产，建立形式多样的玉米转化、加工体系，保证吉林省玉米生产持续稳定发展。  相似文献   

Origin and age of thermal waters in Cieplice Spa, Sudeten, Poland, inferred from isotope, chemical and noble gas data     

W. Cie&#x;kowski  M. Grning  P.M. Leniak  S.M. Weise  A. Zuber 《Journal of Hydrology》1992,140(1-4):89-117

Isotope and hydrochemical data of the thermal water system in Cieplice laskie Zdrój (Spa) indicate the existence of two subsystems that greatly differ in volume and which meet at the fault zones of a granitic horst, where they discharge at an altitude of about 340m. One of the subsystems is very small (about 4 × 10³ m³) as indicated by the tritium age of the order of 10 years and a low outflow rate. Its recharge area found from the δ¹⁸O and δD values, is about 200m above the springs, most probably on the slopes of the foothills of the Karkonosze Mountains south-southwest of the spa. The large subsystem contains water which is free of tritium and whose ¹⁴C content is from 1 to 8 pmc with δ¹³C = −8.0 to −9.2‰. The isotopic composition of this water reflects either the climatic effect (low-altitude recharge during a cooler pre-Holocene climate) or the altitude effect (recharge in the early Holocene period at about 1000m at the heights of the Karkonosze assuming that the ¹⁴C concentration is strongly reduced by exchange with calcite in veins). For the former hypothesis, the recharge area of this water is probably either at the foot of the southeastern slopes of the Kaczawa Mountains or/and at the foot of the Rudawy Janowickie Mountains, to the east of Cieplice. The noble gas temperatures are more consistent with the pre-Holocene recharge. Similarly, the ⁴He excess and ⁴⁰Ar/³⁶Ar ratio support the hypothesis of a pre-Holecene age. The constant ³He/⁴He ratio of 26 × 10⁻⁸ for highly different helium contents indicates crustal origin of helium. For the pre-Holocene age of water its volume is calculated at >- 10⁹m³ (stagnant water in micropores and mobile water in fractures) and the hydraulic conductivity of the host granite massif is estimated at about 7 × 10⁻⁸ ms⁻¹. Two outflows from this subsystem have different and variable fractions of a modern water component (bomb age), most probably originating from the bank infiltration of a nearby stream.  相似文献   

黄骅坳陷三马地区中-深部储层成岩作用及主控因素分析   总被引：12，自引：2，他引：12  

张枝焕  王泽中  李艳霞  钟宁宁  张秀川  张绍辉 《沉积学报》2003,21(4):593-600

黄骅坳陷三马地区储集岩样品的显微特征及成岩矿物的组合关系分析结果表明，三马地区下第三系中深层储层主要处于晚成岩A期，成岩现象包括石英、长石的次生加大、碳酸盐矿物胶结作用、矿物交代作用、溶解作用和粘土矿物转化作用等。其中石英次生加大于2700m左右开始出现，随埋深增大，石英增生加强；长石次生加大现象不十分普遍；碳酸盐胶结作用包括早期自生泥晶方解石胶结作用、连晶方解石和晚期白云石(或铁方解石)的胶结作用。在扫描电镜下可见到方解石与含铁方解石集合体充填在粒间孔隙中或与石英、钠长石及粘土矿物共生，白云岩多呈菱形粒状分布于粒间；常见的交代现象主要有方解石交代长石、石英及粘土矿物，粘土矿物交代长石、石英等；溶解作用主要有长石的溶解、碳酸盐颗粒的溶解和方解石胶结物的溶解等，粘土矿物的转化主要为蒙脱石、高岭石向伊利石(或绿泥石)转化。还讨论了储层岩相、岩性特征、孔隙水中有机酸含量、早期方解石的充填、烃类早期注入等因素对储层成岩演化的控制作用。  相似文献