北京市秋季城区和郊区大气边界层参数观测分析   总被引：16，自引：2，他引：14  

王欣  卞林根  逯昌贵 《气候与环境研究》2003,8(4):475-484

应用2001年9月北京城区和郊区同步大气边界层观测资料,对大气边界层热力和动力参数进行了计算分析.结果表明:北京市秋季,逆温出现的时间城区滞后于郊区;逆温层高度城区大于郊区,200m通常为郊区的逆温层顶和城区的逆温层底部;逆温层强度城区弱于郊区;城市热岛强度为3℃;城区感热通量的输送大于郊区;城区下垫面粗糙度远大于郊区;郊区总辐射和紫外辐射的强度明显大于城区.  相似文献   

Stormwater capture and antecedent moisture characteristics of permeable pavements          下载免费PDF全文

Rui Guo  Yiping Guo  Jun Wang 《水文研究》2018,32(17):2708-2720

An approach based on individual rainfall events is introduced to mathematically describe the hydrologic responses and estimate the stormwater capture efficiencies of permeable pavement systems (PPSs). A stochastic model describing the instantaneous dynamic water balance of a PPS is established, from which the probability distribution of the antecedent moisture content of the PPS at the beginning of a rainfall event is analytically derived. Based on this probability distribution and the event‐based approach, an analytical equation that can be used for estimating the stormwater capture efficiencies of PPSs is also derived. The derived analytical equation is verified by comparing its results with those from continuous simulations for a wide range of PPSs with different sizes and underlying soils and operating under various climate conditions. It was found that the antecedent moisture contents of PPSs at the test locations are usually fairly close to zero, suggesting that PPSs at these locations are always almost empty at the start of a rainfall event. The derived analytical equation accounts for many key processes influencing the behaviour and operation of PPSs; it may serve as an easy‐to‐use tool that is essential for the planning and design of PPSs.  相似文献   

An inter‐basin backwater overflow (the Buhai Brook and the Ezer reservoir on the Jijia River,Romania)          下载免费PDF全文

Gheorghe Romanescu  Cristian Stoleriu 《水文研究》2014,28(7):3118-3131

During the last few years, the north‐western part of Romania has been affected by catastrophic floods with most of the watercourses reaching their highest recorded discharges. This study reports the generation of a numerical terrain model and the simulation of a backwater phenomenon at elevation steps according to the volume of water accumulated at the confluence of the Buhai Brook with the Jijia River. The hydrological data are complemented by rainfall data and the careful recording of the flood behaviour during the entire period of its development. The main aim of the study is to identify the causes of the backwater phenomenon and to highlight the material damage inflicted on the town of Dorohoi. At the same time, the study uses cartographic model that was developed to establish which areas are at risk of flooding at various levels of probability. The catastrophic flood began on the Buhai Brook, a slow‐flowing stream that drains the areas to the west of the town of Dorohoi and discharged into the upstream sector of the Jijia confluence. The flood caused two types of backwater waves: one behind the bridges and the houses built on the floodplain and a second that followed the course of the main stem (Jijia) upstream from the confluence, flooding the Ezer Lake, which was created specifically to attenuate such floods. The spillway backwater phenomenon was inter‐basin as it did not occur in a single hydrographic basin. The causes of the catastrophic flash flood and of the inter‐basin backwater overflow are natural but also reflect anthropogenic influence. After the lake filled, the discharge into the Jijia was controlled and the flooding downstream was thus greatly diminished. Though fortuitous, the backwater flooding was important in mitigating the impact of the flood wave from the Jijia River. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Winkler model for dynamic response of composite caisson–piles foundations: Seismic response     

《Soil Dynamics and Earthquake Engineering》2014

A simplified method with a dynamic Winkler model to study the seismic response of composite caisson–piles foundations (CCPF¹) is developed. Firstly, with the dynamic Winkler model, the kinematic response of the CCPF subjected to vertically propagating seismic S-wave is analyzed by coupling the responses of caisson part and pile part. Secondly, a simplified model for the foundation–structure system is created with the structure simplified as a lumped mass connected to the foundation with an elastic column, and through the Fast Fourier Transformation (FFT) this model is enabled to solve transient seismic problems. Thirdly, the proposed method for the seismic response of CCPF-structure systems is verified by comparison against 3D dynamic finite element simulation, in which the Domain Reduction Method (DRM²) is utilized. Lastly, the mechanism and significance of adding piles in improving the earthquake resistance of the foundation and structure is analyzed through an example with different soil conditions. Discovered in this study is that adding piles under the caisson is an efficient way to increase seismic resistant capability of the soil–foundation–structure system, and the main mechanism of that is the elimination of the pseudo-resonance.  相似文献   

Stormwater control impacts on runoff volume and peak flow: A meta-analysis of watershed modelling studies     

Colin D. Bell  Jordyn M. Wolfand  Chelsea L. Panos  Aditi S. Bhaskar  Ryan L. Gilliom  Terri S. Hogue  Kristina G. Hopkins  Anne J. Jefferson 《水文研究》2020,34(14):3134-3152

Decades of research has concluded that the percent of impervious surface cover in a watershed is strongly linked to negative impacts on urban stream health. Recently, there has been a push by municipalities to offset these effects by installing structural stormwater control measures (SCMs), which are landscape features designed to retain and reduce runoff to mitigate the effects of urbanisation on event hydrology. The goal of this study is to build generalisable relationships between the level of SCM implementation in urban watersheds and resulting changes to hydrology. A literature review of 185 peer-reviewed studies of watershed-scale SCM implementation across the globe was used to identify 52 modelling studies suitable for a meta-analysis to build statistical relationships between SCM implementation and hydrologic change. Hydrologic change is quantified as the percent reduction in storm event runoff volume and peak flow between a watershed with SCMs relative to a (near) identical control watershed without SCMs. Results show that for each additional 1% of SCM-mitigated impervious area in a watershed, there is an additional 0.43% reduction in runoff and a 0.60% reduction in peak flow. Values of SCM implementation required to produce a change in water quantity metrics were identified at varying levels of probability. For example, there is a 90% probability (high confidence) of at least a 1% reduction in peak flow with mitigation of 33% of impervious surfaces. However, as the reduction target increases or mitigated impervious surface decreases, the probability of reaching the reduction target also decreases. These relationships can be used by managers to plan SCM implementation at the watershed scale.  相似文献   

城市创意产业空间动态集聚演化的计算与可视优化方法     

周琦  高长春 《地球信息科学学报》2020,22(5):1033-1048

基于人文地理视角下的城市创意产业图像可视化分析对城市深层次空间综合和区域创新发展具有重大意义。但Swarm群智能动态时空建模难以满足创意产业空间集聚的可视化发展。本文研究目标是,从城市区域创意产业空间聚类影响因素指标出发,创新性地提出区域空间动态集聚轨迹算法（Density-Based Interest Spatial Clustering of Path,DBICP）,并与计算机浏览器共建聚类可视化图像,为城市管理提供决策依据。首先,根据影响因素指标体系,利用2014—2018年空间卡口流量数据和产业指标数据进行预处理,构建空间标准聚类算法DBSCAN。然后,对其进行聚类密度分级优化形成全新DBICP算法并得出初步轨迹图像。最后,通过源码转译实现了浏览器界面下空间动态集聚轨迹图像的输出。结果表明：以上海市为例,普陀区、浦东新区、徐汇地区的创意产业空间分布形成了3种不同的聚类模式,并相应提出了分摊、均布、虹吸的管控策略。此方法克服了传统图像的聚类分级和轨迹测量的缺失,可以有效地从指标数据中发现图像轨迹聚类信息,体现了地理信息科学和人文社会学科的交叉融合。也为大数据动态图像的集聚方法提供了全新视角和借鉴价值。  相似文献   

Long‐term and seasonal hydrologic performance of an extensive green roof          下载免费PDF全文

Dimitar Todorov  Charles T. Driscoll  Svetoslava Todorova 《水文研究》2018,32(16):2471-2482

Sustainable strategies such as green roofs have been implemented as stormwater management tools to mitigate disturbance of the hydrologic cycle resulting from urbanization. Green roofs, also referred to as vegetated roofs, can improve the urban landscape by reducing heat island effects, providing ecosystem services, and facilitating the retention and treatment of stormwater. Green roofs have received particular attention because they do not require acquisition and development of land and represent an application of biomimicry in design and construction. In this paper, we evaluate the effects of precipitation, evapotranspiration (ET), antecedent dry period (ADP), and seasonal variation on the run‐off quantity and distribution of an extensive, sedum covered, green roof on a commercial building in Syracuse, NY, USA. The green roof greatly facilitated retention of precipitation events without significant changes over the 4‐year study. The green roof retained on average 95.9 ± 3.6% (6.5 ± 5.6 mm) per rainfall event, with a range from 75% to 99.6% (33.2 to 3.3 mm). However, as precipitation quantity increased, the retention of water decreased. This high water retention capacity was the result of the combined effects of ET, stormwater storage (plants, growth media, and stormwater retention layer), and limited surface run‐off from the roof deck due to variation in the sloping of the green roof and the tapered insulation to the deck drains. The water retention capacity of the green roof did not change significantly between growing and nongrowing seasons. Slightly greater precipitation during the growing season coincided with increased ET. Average potential ET during the growing season was approximately 3 times greater than during the nongrowing season. The hydrologic performance of the green roof was not significantly impacted by an ADP greater than 2 days.  相似文献   

高质量发展目标下黄河流域城市居民生活质量的时空格局及障碍因子   总被引：2，自引：1，他引：1  

赵宏波  岳丽  刘雅馨  董冠鹏  苗长虹 《地理科学》2021,41(8):1303-1313

提高居民生活质量是实现黄河流域高质量发展的重要目标和具体体现。从居民生活、基础设施、公共服务、生态环境4个方面构建城市居民生活质量评价指标体系,测度2004―2018年黄河流域城市居民生活质量水平,利用核密度估计、ESDA、Dagum基尼系数等方法进行居民生活质量时空格局分析及空间差异测度,并运用障碍因子诊断模型分析影响居民生活质量水平的障碍因子,得出如下结论：① 2004―2018年黄河流域城市居民生活质量高水平区域从下游城市逐渐转移到中上游城市;② 黄河流域城市居民生活质量高?高集聚区主要是内蒙古自治区及相邻区域的城市,低?低集聚区主要是河南省、山东省以及山西省的部分城市;③ 黄河流域城市居民生活质量水平的空间差异从上中下游尺度看主要是区域间净值差异贡献,从左右岸尺度看主要是区域内部差异贡献;④ 黄河流域城市居民生活质量水平的障碍因子主要是人均水资源量、移动电话年末用户数、每万人公园绿地面积、教育支出占财政支出比重、每万人拥有的道路面积与人均可支配收入等,因此在未来的高质量发展中要注重生态环境保护,特别是合理利用水资源,完善城市基础设施与提升公共服务水平。  相似文献   

多维邻近下浙江城市创新网络演化及其机制研究   总被引：4，自引：0，他引：4  

王庆喜  胡志学 《地理科学》2021,41(8):1380-1388

以浙江90个县级城市（城区）为对象,基于大数据专利文本挖掘析取城市间合作申请专利数,构建创新网络,采用空间网络模型和负二项回归模型分析2007—2017年浙江城市创新网络的网络结构、时空演化及创新合作强度的影响机制。研究发现：① 浙江城市创新网络规模逐渐扩张,“小世界性”显著,通达性较好,整体呈以杭州湾区为核心的“网络局部化、辐射中心化”特征,等级层次性清晰;② 浙江城市创新合作强度与经济规模、教育水平、政策支持、技术势差、城市行政等级、技术邻近性、边界相邻效应显著正相关且受地理距离约束,认知邻近性和制度邻近性与创新合作间分别呈“U”型和倒“U”型曲线关系,网络效应更多在整体网层面上促进了创新合作。在特定省份县级城市层面探讨了如何加强城市创新网络协同效应,以促进地方城市间的创新联系。  相似文献   

中国三大城市群电子商务快递物流网络空间结构及其形成机制研究     

李苑君  吴旗韬  张玉玲  吴康敏  张虹鸥  金双泉 《地理科学》2021,41(8):1398-1408

以中国长三角、京津冀、珠三角三大城市群为案例,基于中国智能物流骨干网（China Smart Logistic Network,CSN）关系数据,采用社会网络分析、随机森林分类算法、QAP分析等研究方法,在县区尺度上探索电子商务快递物流网络空间结构特征及其形成机制。研究发现：① 三大城市群电商快递物流网络密度较高,已形成典型的网络式空间结构。其中长三角城市群网络呈圈层蛛网式结构,县区间联系强度以环杭州湾为中心向外围梯度衰减;京津冀城市群网络受制于行政藩篱,形成“北京?天津”双核心网络结构;珠三角城市群网络联系强度自区域外围由弱到强逐渐向珠江口东岸方向变化,形成“穗（广州）?莞（东莞）?深（深圳）”快递物流廊道。② 三大城市群中物流输出型县区多集中在区域中部,依托中心城市向外物流辐散,而物流输入型县区多分散于外围。③ 城市群电商快递物流网络形成主要受人均可支配收入、常住人口和距离等因素影响。研究结果对于丰富城市网络理论,促进城市群快递物流协调发展,提升现代服务业水平和城市群整体竞争力具有重要意义。  相似文献