Non-Darcian groundwater flow in leaky aquifers     

ZEKAI ŞEN 《水文科学杂志》2013,58(4):595-606

Abstract

A simplified method has been developed for solving leaky aquifer non-Darcian flow hydraulics. The principle of volumetric approach is combined with the confined-aquifer, time-dependent drawdown equation in an observation well. The groundwater flow in the leaky aquifer is assumed to obey a non-Darcian flow law of exponential type. The results are obtained in the form of type-curve expressions from which the necessary bundles of curves are drawn for a set of selective non-Darcian flow aquifer parameters. Although application of the methodology appears as rather limited but it provides a scientific contribution and extension of leaky aquifer theory towards nonlinear flow conditions. The methodology developed herein is applied to some actual field data from the eastern sedimentary basin in the Kingdom of Saudi Arabia.  相似文献   

Dynamic Relationship Between Entrainment Rate and Summer Monsoon in the Transition Area of Monsoon in the East of Northwest China     

Yanying Li  Ying Cai  Chunyan Zhang  Ting Zeng  Jiping Yang 《地球科学进展》2019,34(12):1316-1327

Entrainment rate refers to the ratio of surrounding air quality to air quality involved in rising unit distance, including turbulent entrainment and dynamic entrainment, which are applied to the boundary layer parametrization of convective clouds, the improvement of numerical model, the observation of cloud droplet spectral dispersion and the study of tropical cyclones.Based on the daily data at 07:00 and 19:00 every 10 m of five stations such as Minqin, Yuchong, Pingliang, Yinchuan and Yan'an from May to September during 2006-2016, combined with the daily observation data on the ground, the Entrainment Rates(ER) of different heights were calculated, and the relationships between ER and height in different regions, precipitation as well as monsoon during the monsoon period were further obtained. The main results were as follows:\mathrm{①} The ER was proportional to air temperature and saturated water vapor pressure, but inversely proportional to relative humidity. The relative humidity threshold of cloud was 65%. The higher the relative humidity threshold was, the lower the cloud height of different orders of precipitation was, and the cloud height was higher with the increase of rainfall. \mathrm{②}ER had obvious diurnal changes and regional differences: It was obviously smaller at 07:00 than at 19:00 from ground to 3 km, which weakened with the increase of height in the near surface , but strengthened with the increase of height above 500 m; From small to large, the monsoon affected area, the monsoon swing area and the non-monsoon area were in turn, and there was no regional difference above 3 km. \mathrm{③} ER was closely related to the intensity and property of precipitation in monsoon period. The ER weakened with the enhancement of rain intensity from near ground to below 600 m, but strengthened with the enhancement of rain intensity from 500 m to 2~3 km.From near ground to below 700 m, the ER of stable precipitation was strong, but that of convective precipitation was strong above 700 m. The convective precipitation had big saturated water vapor pressure and strong ER , while the stable precipitation had big saturated water vapor density, rich water vapor but weak ER. \mathrm{④}The relationship between ER and monsoon as well as its duration: From no monsoon to monsoon ER was weakened, the strongest maximum height was also decreasing. There was no significant difference in the duration of ER between the non-monsoon area and the monsoon affected area, but the longer the monsoon swing area lasted in the near ground layer, the smaller the ER was, while the opposite was at 1~2 km in the high altitude. \mathrm{⑤}The relationship between ER and the APO monsoon intensity index showed that: At 07:00, the ER strengthened with height from near ground to below 800 m, but weakened with height above 800 m,and the monsoon intensity was not related to the ER. At 19:00, the ER strengthened with the height near ground but weakened with the height above 300 m, and the stronger the monsoon was, the smaller the ER was. The ER weakened with the decrease of boundary layer height.  相似文献   

基于人地关系理论的河南省主体功能区规划研究   总被引：4，自引：2，他引：2  

冯德显  张莉  杨瑞霞  赵永江 《地域研究与开发》2008,27(1):1-5

以人地关系理论分析为基本切入点,通过对人地关系地域系统演化的历史剖析,探讨形成主体功能区的时代背景和现实意义.从规划的政治经济和科学发展等不同层面分析了主体功能区构建的实践价值.结合河南人地关系发展现状,以构建和谐的人地关系为目标,对河南省主体功能区进行了研究,对河南省主体功能区划分的基本构思进行了介绍.最后,对目前进行的主体功能区划若干问题进行了探讨.  相似文献   

东海梭子蟹亚科常见属的亲缘关系分析     

吴惠仙  王琼  徐雪娜  刘艳  董双林  王芳  薛俊增 《海洋学报》2012,34(1):178-182

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基于线粒体基因的石珊瑚分子系统学研究   总被引：2，自引：0，他引：2  

刘丽  李晓娜  陈育盛  刘楚吾 《海洋与湖沼》2012,43(4):814-820

以广东徐闻地区常见的6科10属17种石珊瑚的21个样本为研究对象,对线粒体COⅠ、16SrRNA和mtSSU三基因片段数据进行了联合分析,并计算了属间和科间遗传距离;利用邻接法、最大简约法和最大似然法分别构建了分子系统树。序列分析结果显示,石珊瑚线粒体基因碱基构成同样具有AT偏倚特征;石珊瑚属间的遗传距离显著大于属内遗传距离,而所有石珊瑚与两个外类种群的距离均大于石珊瑚之间的遗传距离;在系统发育树中,分子系统分类结果与形态学分类阐述的遗传进化关系略有差别,暗示传统形态学分类可能受珊瑚骨骼生长可塑性限制。  相似文献   

Reconciling classifications of ecologically and biologically significant areas in the world’s oceans     

Edward J. Gregr  Andrea L. AhrensR. Ian Perry 《Marine Policy》2012,36(3):716-726

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武汉城市群交通运输体系与城镇空间扩展关联分析   总被引：1，自引：0，他引：1  

关兴良  蔺雪芹  胡仕林  鲁莎莎 《地理科学进展》2014,33(5):702-712

交通运输体系与城镇空间扩展的关联分析是揭示交通运输与经济增长作用关系的重要切入点。采用等时线叠置法和指标分区法,分析了武汉城市群交通可达性及交通优势度与城镇空间扩展的时空格局、关联特征及其作用机理。研究表明,交通运输体系与城镇空间扩展具有内在联系,呈现出互动耦合、协同演进格局。从作用机理来看,交通运输体系通过直接效应、外部效应和乘数效应对城镇空间扩展起着重要的支撑和推动作用;城镇空间扩展在“量”和“质”上对交通运输提出了新要求,刺激并保障了交通运输体系的发展,两者相互反馈、相互依赖。从政策启示来看,交通运输体系的空间不均衡是造成区域经济发展水平差异的重要因素,制定差别化的交通运输发展战略和完善一体化的交通运输体系是加快区域经济增长和缩小地区差距的重要途径。  相似文献   

亚洲夏季风各子系统主要变率相互关系初析   总被引：1，自引：0，他引：1  

吴进  何金海  张祖强  祁莉 《热带气象学报》2011,(5):619-625

使用NCEP/NCAR再分析资料和CMAP月平均降水资料分析了亚洲夏季风各个子系统的相互关系。结果表明亚洲夏季风子系统之间存在显著相关。从同期强度变化可知,当东亚季风偏强时,大尺度亚洲季风、东南亚季风、南亚季风均偏弱,相关区域降水偏少;而同时大尺度亚洲季风偏强时,东南亚和南亚季风偏强,相关区域降水偏多;东南亚季风偏强时,南亚季风偏弱,南亚地区降水偏少;反之亦然。从不同周期强度变化可知各个子系统相关仍然显著。   相似文献   

30年来东南红壤丘陵区土壤侵蚀度时空演变研究——以长汀县为例   总被引：7，自引：0，他引：7  

林晨  周生路  吴绍华 《地理科学》2011,31(10):1235-1241

土壤侵蚀动态监测是侵蚀研究体系中的重要内容,当前国内大部分研究直接引用国外监测模型,不仅在因子选取以及模型通用性上存在不足,而且对区域土壤的潜在性侵蚀危险考虑不够。因此,研究提出土壤侵蚀度的概念,作为区域土壤实际侵蚀强度与潜在侵蚀危险的综合表征,并基于人地关系系统,通过多指标的量化与建模进行土壤侵蚀度测算,从而分析福建省长汀县土壤侵蚀时空演变规律。结果表明,长汀县土壤侵蚀分布存在集中连片的特点,汀中地区的侵蚀度最高,并向周边逐渐衰减。同时,侵蚀度在变化方向上虽然存在不确定性,但总体侵蚀状况近30a来得到了明显的改善,安全区的比重从1975年的3.87%增长至2006年的56.38%,相比而言,极度侵蚀危险区的比重仅从1975年的12.3%,减少至2006年的6.66%,改善幅度较其他等级土壤有所差距,这与区域在立地条件、经济发展水平以及政策导向上的差异密切相关。研究结果说明选取侵蚀影响因子具有一定的适宜性,也证明土壤侵蚀度可以有效表征土壤侵蚀时空演变趋势。  相似文献   

四氢呋喃水合物沉积物静动力学性质试验研究   总被引：1，自引：0，他引：1  

张旭辉  鲁晓兵  王淑云  李清平 《岩土力学》2011,32(Z1):303-0308

利用研制的天然气水合物沉积物合成与力学性质测试一体化试验设备,以粉细砂土和蒙古砂土作为沉积物骨架,对四氢呋喃(THF)水合物沉积物进行了静动三轴试验,获得了水合物分解前后沉积物样品的应力-应变关系、强度和液化特性,对两种骨架的水合物沉积物的性质进行了对比,同时将水合物分解后的沉积物与对应的饱和土的动三轴试验结果进行了对比。结果表明：水合物沉积物均表现为塑性破坏;围压越大,水合物沉积物强度越高;水合物分解导致沉积物的强度大幅降低;水合物分解后沉积物液化所需的时间较饱和水沉积物缩短  相似文献