基于主成分分析和因子分析的宁夏水资源承载力研究   总被引：4，自引：1，他引：3  

赵自阳  李王成  王霞  崔婷婷  程载恒  王帅 《水文》2017,37(2):64-72

为了探求宁夏水资源承载力状况,利用主成分分析法和因子分析法,在分析宁夏2004~2014年水资源承载力状况的基础上,对宁夏5市2013年水资源承载力分水资源支持力、社会经济技术水平和社会生活水平3个方面进行综合考虑,得到宁夏5市的水资源利用状况指数和分级标准。具体得到以下几个结论:(1)2004~2014年间,宁夏水资源承载力仅在2005~2006年有所波动,其余年份两种方法结果一致,11年间保持稳定上升;(2)对于宁夏5市2013年水资源承载力状况,主成分分析结果由大到小排序为吴忠市、银川市、石嘴山市、固原市和中卫市,因子分析结果由大到小排序为吴忠市、银川市、固原市、石嘴山市和中卫市;(3)建立宁夏5市水资源承载力状况分级阈值,主成分分析下吴忠市和银川市的水资源利用状况高,石嘴山市的水资源利用状况中等,固原市和中卫市的水资源利用状况低;因子分析下吴忠市和银川市的水资源利用状况高,其余3市水资源利用状况都较低。  相似文献   

Finite-difference model of land subsidence caused by cluster loads in Zhengzhou,China          下载免费PDF全文

ZHAO Yue-wen  WANG Xiu-yan  LIU Chang-li  LI Bing-yan 《地下水科学与工程》2020,8(1):43-56

Groundwater exploitation has been regarded as the main reason for land subsidence in China and thus receives considerable attention from the government and the academic community.Recently,building loads have been identified as another important factor of land subsidence,but researches in this sector have lagged.The effect of a single building load on land subsidence was neglected in many cases owing to the narrow scope and the limited depth of the additional stress in stratum.However,due to the superposition of stresses between buildings,the additional stress of cluster loads is greater than that of a single building load under the same condition,so that the land subsidence caused by cluster loads cannot be neglected.Taking Shamen village in the north of Zhengzhou,China,as an example,a finite-difference model based on the Biot consolidation theory to calculate the land subsidence caused by cluster loads was established in this paper.Cluster loads present the characteristics of large-area loads,and the land subsidence caused by cluster loads can have multiple primary consolidation processes due to the stress superposition of different buildings was shown by the simulation results.Pore water migration distances are longer when the cluster loads with high plot ratio are imposed,so that consolidation takes longer time.The higher the plot ratio is,the deeper the effective deformation is,and thus the greater the land subsidence is.A higher plot ratio also increases the contribution that the deeper stratigraphic layers make to land subsidence.Contrary to the calculated results of land subsidence caused by cluster loads and groundwater recession,the percentage of settlement caused by cluster loads in the total settlement was 49.43%and 55.06%at two simulated monitoring points,respectively.These data suggest that the cluster loads can be one of the main causes of land subsidence.  相似文献   

第四次国际古气候模拟比较计划（PMIP4）概况与评述     

郑伟鹏  满文敏  孙咏  栾贻花 《气候变化研究进展》2019,15(5):510-518

古气候模拟比较计划（PMIP）是古气候数值模拟领域一项重大的国际合作研究计划,其主旨是为古气候模拟和模拟结果评估提供一个协调机制,理解过去气候变化的物理机制和气候反馈的重要作用,为未来气候预估提供科学依据。同时,通过对比分析验证模式的模拟性能,探索其不确定性,促进耦合气候系统模式的发展。PMIP目前进行到第四阶段（PMIP4)。PMIP4进一步加强了与第六次国际耦合模式比较计划（CMIP6）的协作,选取了5组共同关注的PMIP4-CMIP6古气候模拟试验（中全新世、末次盛冰期、过去千年、末次间冰期和上新世暖期),考察气候系统对不同气候背景的综合响应。除此以外,PMIP4还设计了众多敏感性试验研究不同外强迫因子的影响。PMIP4模拟试验不仅为古气候研究提供大量的模拟数据,还将服务于CMIP6及其他众多模式比较计划。  相似文献   

The Effect of Stage on Flow and Components of the Local Force Balance     

Peter J. Whiting 《地球表面变化过程与地形》1997,22(6):517-530

Flow fields and water and bed surface topography were measured at two different stages as flow shoals over a submerged mid-channel bar in a straight reach downstream of a bend in Solfatara Creek, Wyoming. The data allow calculation and comparison of the magnitude of the component terms in the downstream and cross-stream force balance at the different stages. At the lower stage, corresponding to a discharge that is 30 per cent of the bankfull discharge, the convective acceleration terms in the equations describing the force balance are important, particularly the terms associated with the cross-stream transport of momentum. These terms are large because of the large accelerations and cross-stream flow forced by the shallow flow over the bar. At the higher stage, corresponding to a discharge that is 45 per cent of the bankfull discharge, flow is more directly downstream and cross-stream velocity is generally less in most of the channel. Downstream flow velocities at the higher stage are larger, but the acceleration is more gradual. Consequently, the convective accelerations at the higher stage tend to be less important than at the lower stage. Results from the two different stages suggest that some of the difference in conclusions reached by various workers on the significance of the various terms in the governing equations may be associated with the relative depth of flow. © 1997 John Wiley & Sons, Ltd.  相似文献   

非洲投资环境地域差异研究   总被引：5，自引：1，他引：4  

尹海伟  徐建刚  曾尊固  龙国英 《世界地理研究》2005,14(2):25-31

本文在总结国内外投资环境研究方法的基础上,根据区域特殊性、综合性与可操作性等原则构建了由30项指标组成的指标体系,采用主成分分析的数据处理方法,对非洲各国投资环境进行了综合定量评价,将其分为优（I≥2）、良（1≤I〈2）、差（0．8≤I〈1）和极差（I〈0．8）四大类,以便为我国企业对非投资提供决策参考。  相似文献   

南京地电阻率长趋势变化与区域应力调整的关系研究          下载免费PDF全文

王丽  叶青  周康雅  丁烨 《地震工程学报》2020,42(1):143-149,214

江苏南京台北南测道2013—2016年年初出现了与邻近的南京江宁台同步的地电阻率长趋势上升变化,2016年的年中出现了与江宁台和稍远距离的江苏高邮、新沂台同步的趋势下降变化。本文用年变形态、消除年变等数据处理方法并联系该区降雨量分析了南京台等地电阻率长程观测数据,基于视电阻率变化与地下介质内部骨架电阻率ρ°、裂隙水电阻率ρf、裂隙率ν之间的本构关系讨论了地电阻率趋势变化的原因,得到:该台南北向测道地电阻率趋势上升变化起因于台站及周边区域性地下介质的应力调整过程,动力来源可能是本区域地壳局部构造运动。  相似文献   

动态应力触发研究进展     

陈昊  冀战波  王琼  苏金波 《中国地震》2020,36(3):442-459

本文从库仑破裂应力与动态应力触发原理、观测事实与研究现状以及存在的问题与展望等3个方面介绍了动态应力触发的研究进展。其中,在主震对余震活动、强震对后续远场地震活动、不同破裂类型的地震之间及强震对火山(泥火山)的动态应力触发作用、一次大地震中子事件之间的动态应力触发关系以及动态应力触发的时间延迟等方面进行了详细讨论。分析认为,动态应力触发理论在解释震后余震分布、远程触发以及对火山触发性喷发等方面得到了较好的结果;动态应力触发可能会受断层破裂方式和方向的影响;大地震中子事件之间的动态应力触发关系对震源研究有重要意义;动态应力触发现象普遍存在时间延迟。  相似文献   

横观各向同性场地中埋置衬砌隧道对qP波的散射          下载免费PDF全文

巴振宁  安东辉  梁建文  高旭 《地震工程学报》2020,42(4):948-954

采用间接边界元法(IBEM)结合"分区契合"技术,研究qP波入射下横观各向同性(TI)场地中衬砌隧道的动力响应问题。方法充分利用半空间和全空间动力格林函数在分别构造含孔半无限空间域和闭合域内散射波场方面的优势,将含有衬砌隧道的层状弹性半空间分解为含孔半无限空间域和一个环形衬砌闭合域来分别进行波场构造,有效地降低了求解时间和存储量。文中验证方法的正确性,并以均匀TI半空间和基岩上单一TI土层为例,计算分析弹性半空间场地中隧道衬砌内表面动应力放大问题。结果表明qP波入射下,TI介质与各向同性介质场地中埋置衬砌隧道的动力响应差异显著,TI介质参数的变化导致场地动力特性的改变,进而改变场地与衬砌隧道的动力相互作用机制,显著影响着衬砌内表面动应力的大小及其空间分布。  相似文献   

Geochemical evolution of groundwater in hard-rock aquifers of South India using statistical and modelling techniques     

Annadasankar Roy  Hemant Mohokar  Diksha Pant  Uday Kumar Sinha  G. N. Mendhekar 《水文科学杂志》2020,65(6):951-968

ABSTRACT

Multivariate statistical analysis and inverse geochemical modelling techniques were employed to deduce the mechanism of groundwater evolution in the hard-rock terrain of Telangana, South India. Q-mode hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to extract the hydrogeochemical characteristics and classify the groundwater samples into three principal groups. Use of thermodynamic stability diagrams and inverse geochemical modelling in PHREEQC identified the chemical reactions controlling hydrogeochemistry of each of the groups obtained from statistical analysis. The model output showed that a few phases are governing the water chemistry in this area and the geochemical reactions responsible for evolution of groundwater chemistry along the flow path are (i) dissolution of evaporite minerals (dolomite, halite); (ii) dissolution of primary silicate minerals (albite, anorthite, K-feldspar, biotite); (iii) precipitation of secondary silicate minerals (kaolinite, quartz, gibbsite, Ca-montmorillonite) along with anhydrite and calcite; and (iv) reverse ion exchange processes.  相似文献   

鄂尔多斯块体西南缘地区震源机制解与构造应力场特征分析     

王莹  赵韬  刘春  冯希杰 《地震地磁观测与研究》2020,41(4):18-25

计算了2001年1月至2018年9月鄂尔多斯块体西南缘地区（33°—38°N,103°—109°E）M_L≥3.0地震的震源机制,分析了该区域震源机制解特征,在此基础上,采用平均矩张量技术反演了该区域的构造应力场特征。结果表明,研究区震源机制类型以走滑型和逆冲型为主,其空间分布基本与区域构造动力背景和断裂性质一致,少量不符合区域构造性质的震源机制则反映了局部地质构造的复杂性。区域构造变形主体为NE向压缩,NW向相对扩张,反映了青藏高原块体对鄂尔多斯块体的直接作用。  相似文献