Comparisons of two global built area land cover datasets in methods to disaggregate human population in eleven countries from the global South

Mapping built land cover at unprecedented detail has been facilitated by increasing availability of global high-resolution imagery and image processing methods.These advances in urban feature extraction and built-area detection can refine the mapping of human population densities,especially in lower income countries where rapid urbanization and changing population is accompanied by frequently out-of-date or inaccurate census data.However,in these contexts it is unclear how best to use built-area data to disaggregate areal,count-based census data.Here we tested two methods using remotely sensed,built-area land cover data to disaggregate population data.These included simple,areal weighting and more complex statistical models with other ancillary information.Outcomes were assessed across eleven countries,representing different world regions varying in population densities,types of built infrastructure,and environmental characteristics.We found that for seven of 11 countries a Random Forest-based,machine learning approach outperforms simple,binary dasymetric disaggregation into remotely-sensed built areas.For these more complex models there was little evidence to support using any single built land cover input over the rest,and in most cases using more than one built-area data product resulted in higher predictive capacity.We discuss these results and implications for future population modeling approaches.

Assessment of Human Impacts on Vegetation in Built-up Areas in China Based on AVHRR,MODIS and DMSP_OLS Nighttime Light Data,1992–2010

Since the reform and opening-up program started in 1978,the level of urbanization has increased rapidly in China.Rapid urban expansion and restructuring have had significant impacts on the ecological environment especially within built-up areas.In this study,ArcGIS 10,ENVI 4.5,and Visual FoxPro 6.0 were used to analyze the human impacts on vegetation in the built-up areas of 656Chinese cities from 1992 to 2010.Firstly,an existing algorithm was refined to extract the boundaries of the built-up areas based on the Defense Meteorological Satellite Program Operational Linescan System(DMSP_OLS)nighttime light data.This improved algorithm has the advantages of high accuracy and speed.Secondly,a mathematical model(Human impacts(HI))was constructed to measure the impacts of human factors on vegetation during rapid urbanization based on Advanced Very High Resolution Radiometer(AVHRR)Normalized Difference Vegetation Index(NDVI)and Moderate Resolution Imaging Spectroradiometer(MODIS)NDVI.HI values greater than zero indicate relatively beneficial effects while values less than zero indicate proportionally adverse effects.The results were analyzed from four aspects:the size of cities(metropolises,large cities,medium-sized cities,and small cities),large regions(the eastern,central,western,and northeastern China),administrative divisions of China(provinces,autonomous regions,and municipalities)and vegetation zones(humid and semi-humid forest zone,semi-arid steppe zone,and arid desert zone).Finally,we discussed how human factors impacted on vegetation changes in the built-up areas.We found that urban planning policies and developmental stages impacted on vegetation changes in the built-up areas.The negative human impacts followed an inverted′U′shape,first rising and then falling with increase of urban scales.China′s national policies,social and economic development affected vegetation changes in the built-up areas.The findings can provide a scientific basis for municipal planning departments,a decision-making reference for government,and scientific guidance for sustainable development in China.

Space-time Relationship Between Urban Municipal District Adjustment and Built-up Area Expansion in China

Municipal district adjustment and built-up area expansion are two main forms of urban spatial expansion. Using geometric methods, this study constructed a space-time path method to characterize the space-time relationship between municipal district adjustment and built-up area expansion, and drew the space-time path sets of major prefecture level cities from 2000 to 2010 by constructing a coordinate system of the standardized built-up areas and municipal district areas. This divided them into four quadrants, namely, H-H, L-H, L-L, and H-L, based on the relative mean value to evaluate overall and individual stability by three indexes of the trajectory vectors, namely, direction, length, and slope. Results provide the following conclusions. 1) Municipal district adjustment is an effective spatial expansion way for city-scale promotion in China. Since 2000, municipal district adjustments have been mainly distributed in the eastern coastal regions and mid-western capital cities along with their surrounding cities. 2) Municipal district adjustment affects the scale and status of a city in China. Many cities that have expanded municipal districts behave stably and cross quadrants. 3) Great majority second-tier cities have effectively promoted their scale and status through municipal district adjustment. The municipal district adjustment of medium and small cities in the mid-west area is relatively advanced compared with city development. 4) Municipal district adjustment with minimal magnitude is severely restricted from upgrading the scale and status of a city. The transformation from entirely incorporated counties or cities to municipal districts should be the mainstream in future municipal district adjustment.

Ecological Optimization Design Methods for the Green Space System in Densely Built-up Areas

This paper is aimed at studying the environmental degradation of densely built-up areas in the process of urbanization in China. In consideration of the severe environmental conditions of the densely built-up areas, such as the lack of green space and open space, ecological disturbance in some areas, poor landscape quality, this paper focused on the ecological space optimization in the process of urban renewal. Firstly, theories related to this field were analyzed, and a comprehensive ecological efficiency evaluation system was established based on disciplines such as urban ecology, landscape ecology, urban sociology, behavioral psychology, biology, urban planning and design. Secondly, this system was used to judge the ecological efficiency of typical blocks on GIS platform and to find out the key spatial nodes that need to be updated. Thirdly, in different cases, space optimization projects with different theories were designed, and the spatial model of influence was used to comprehensively evaluate their ecological efficiency. Finally, the parameters under different conditions were corrected to get a systematic system for evaluating the green space system in densely built-up areas. Due to the lack of understanding of the ecological function of green space in the past, the environmental condition of densely built-up areas is not good. Therefore, the most important task of urban organic renewal is ecological restoration. In this paper, the exploration is based on the reservation for built-up areas to avoid repeated reconstruction and interference. Authors of this paper tried to find out a way to rebuild green space system that performed more complex functions with limited spatial resources. The application of "micro-transformation" of green space system in densely built-up areas turns out to improve the quality of landscape while reducing the construction cost.

Examining Rate of Built-Up Areas on the Vegetation Cover along River Riara Riparian within Kiambu Town, Kenya

Urban river riparian spaces and their natural systems are valuable to urban dwellers;but are increasingly affected and ruined by human activities and in particular, urbanization processes. In this research, land sat and sentinel satellite imagery apt for change detection in vegetation cover, both landsat and sentinel imagery, covering the period between 1970 and 2021 in epochs of 1973, 1984, 1993, 2003, 2015 and 2021 years were used to establish the correlation between vegetation cover and built-up area along River Riara river reserve. The images were analysed to extract the built-up areas along the river reserve, including the buildings, and the rate of human settlements, which influenced vegetation cover. Normalized Difference Built-Up Index (NDBI) and Normalized Difference Vegetation Index (NDVI) were computed using the Short-Wave Infrared (SWIR) and the Near Infra-Red (NIR) bands to show the rate of change over the years. Results indicate NDVI values were high, compared to NDBI values along river Riara in the years 1973 and 1993 implying that there was more vegetation cover then. However, in the year 2021, the NDVI indicated the highest value at 0.88, with the complementary NDBI indicating the highest NDBI value at 0.47. This represents a significant increase in built-up areas since 2015 more than in previous epochs. Either, there was a significant increase in NDBI values, from 0.24 in 1993 to 0.47 in 2021. More so, the R-squared value at 0.80 informed 80% relationship between NDBI and NDVI values indicating a negative correlation.

基于多源数据与随机森林方法的城市建成区提取——以郑州市为例

基于夜间灯光数据的阈值分割法在城镇建成区提取研究中被广泛应用,但由于夜间灯光数据分辨率低、灯光溢出和阈值分割法无法顾及区域差异等问题,一定程度上影响了该方法的提取精度。以郑州市为例,以LJ1-01与NPP/VIIRS两种夜间灯光影像为主要数据源,结合Landsat8中分辨率遥感影像、网络城市兴趣点(POI)及路网数据,利用随机森林分类方法对郑州市2018年建成区进行提取,参考土地利用数据,对RF分类法与NTL、VANUI、BANUI、PANUI、RANUI指数等阈值法进行对比实验和精度评价,评估基于多源数据的随机森林分类方法在城市建成区提取中的优势。实验表明,RF比阈值法提取的建成区更接近真实建成区且提取精度更高,具有更好适用性;LJ1-01数据提取的效果和精度总体优于NPP/VIIRS数据;在采用RF分类时,各类特征的重要性在不同夜光数据源中表现差异较大。

高密度建成区污水治理提升规划与实施体系研究

污水处理提质增效是存量规划背景下城市更新的重要内容,是改善城市人居生态环境的有效路径。结合城市可持续发展、高质量发展的新要求,以厦门市思明区为研究对象,提出了排水现状排查和数字化的技术方法,探索总结了高密度建成区“溯源排查、正本清源、排水管理进小区”污水治理提升规划模式。借助“多规合一”的国土空间规划体系,针对性地提出技术标准、实施细则和政策规章等配套措施,建立了污水治理系统“智慧型”信息管理平台,构建了完善的规划实施体系,有效统筹了高密度建成区污水治理的“规划、建设、管理”三大环节,为新时期推动污水治理体系和治理能力现代化提供新思路。

平原城市高度建成区暴雨内涝模拟及防治研究

针对平原城市高度建成区暴雨引发的城市内涝问题,以珠三角城市东莞市为例,基于MIKE FLOOD平台,利用MIKE URBAN、 MIKE 11和MIKE 21构建了城市内涝耦合模型。同时,结合历史暴雨事件提出一种长历时暴雨设计雨型,分析50 a一遇设计降雨重现期下东莞市中心城区暴雨内涝过程和积水特征,提出改善“大排水系统”排水能力的内涝治理措施并评估其实施效果。结果表明:东莞市中心城区内涝的主要原因为河道水流顶托及道路排水不畅,河道拓宽整治结合道路竖向调整可使管网溢流程度降低45%,内涝淹没面积减小73%。提高研究区内河、道路排水通道等“大排水系统”的排水能力对改善研究区域的内涝现状效果显著。研究成果可为平原城市高度建成区的内涝治理提供技术支撑。

景观格局汇水单元法与城区水量水质模拟研究

景观多样性有助于提高城市韧性,但其可能带来的透水斑块破碎化和廊道连通度的改变,会影响城区非点源污染的产生输移特性。传统对非点源污染的定量评估忽略了汇水单元内部景观格局(形状、比例和空间配置)对物质输移的影响,是导致模拟精度偏低的主要原因。针对这一问题,本研究结合遥感影像和城市景观格局分布特征,构建了基于景观格局的汇水单元划分方法(景观格局法)。采用SWMM模型,以巢湖一级支流十五里河为对象展开研究,结果表明:(1)基于实测数据进行验证,采用景观格局法模拟各项指标(水量、COD、TP和NH 3-N)的纳什效率系数(NSE)均大于0.7,结果可靠;(2)与传统方法(泰森多边形划分汇水单元)相比,水量模拟精度(以NSE计)提高8%,水质模拟精度提高6%;(3)与泰森多边形法相比,景观格局法计算的入河总水量和污染总负荷较低,且污染物浓度峰值滞后;(4)景观格局法通过改变汇水单元之间的水力联系,模拟出污染物冲刷减弱,初期雨水冲刷效应降低,且随着重现期的加大,降低初期雨水冲刷强度的效果越明显,表明一定程度上景观类型多样化有助于缓解瞬时高强度污染影响。本研究构建的方法充分考虑了城市斑块内部的景观格局分布特征和水力联系,可为城区面源污染输出控制提供新的评估手段。

高密度城区居住用地附属绿地对生态连通性影响——以深圳市福田区为例

文章通过识别生态源地、提取居住用地附属绿地,基于最小阻力模型,分析居住用地附属绿地支持与阻隔生物流通情景下的生态网络,探讨居住用地附属绿地对高密度城区生态连通性的影响,提出保护建议。结果表明:1)福田区中部莲花山公园、东部荔枝公园、南部皇岗公园生态连通性受其周围居住用地内连片或连续分布的带状附属绿地影响较大。2)居住用地附属绿地对生态连通性的影响体现在减小廊道阻力,其中对中阻力廊道的影响最大(单位成本距离下降29.2%);使具有重要生态保护价值的区域连片;能缓解在高密度建成区中的狭窄低阻力通道处形成夹点的情况。3)不同居住用地附属绿地连通情景下、不同阻力阈值下生态网络中重复出现的生态夹点被定为是最具有保护价值的一级夹点。根据不同情景下重复出现的生态夹点位置的重要性等级分类,针对性提出支持城市生态连通性的保护措施。建议加强新洲路福民路交汇处等一级夹点4处,优先保护靠近源地且位于源地间拓扑连接上的、规模超过平均规模5920.22 m^(2)的居住用地附属绿地。

深圳市高密度建成区再生水利用配置探索

针对超大城市建成度高、管网建设难度大、本地水资源供给严重不足、用水效率不高等问题,深圳在较为完善的再生水生态补水系统基础上,详细调查再生水利用现状及潜在用户,瞄准重点大用户和重点区域,系统开展再生水利用配置,进一步提高再生水替代常规水资源利用量。通过开展“1453”试点建设行动,以点带面,全市域推进,扩大再生水利用领域。总结探索超大城市政府引导下的市场化再生水利用配置策略及经验做法,以期为深圳及相似城市经济社会高质量、可持续发展提供有力支撑。

微观建成环境对地铁站域可步行性的影响研究——以大连为例

以大连中心城区内7个地铁站点周边800 m范围内的步行空间环境为研究对象,通过对719名步行者进行问卷调查,借助结构方程模型,探析微观建成环境与站域可步行性的内在关联。研究发现,存在6个潜变量影响站域可步行性,“便捷性”占主导地位。结合实地调研情况,识别出建成环境中的人行道过街、天桥过街、地下通道过街和指示标识是高效失衡型指标,并针对性地提出优化建议。

多源数据加权融合的城市建成区改进指数评估

针对多源数据提取建成区的研究大多集中在等权融合方向,缺乏考虑不同数据源包含的信息量差异的问题,通过多源数据加权融合方法对前人的城市建成区提取指数进行改进,以改善不同质量级数据直接融合导致建成区提取不准确的问题。首先,构建融合夜间灯光数据、NDVI数据、路网数据和POI数据的改进PREANI指数;其次,融入不透水面数据和温度数据构建无权指数UCI和有权指数WCI;最后,选择迭代法和动态阈值法提取建成区,并对3种指数分别进行评估。结果表明:改进PREANI的Kappa系数为0.80,UCI融入温度和不透水面数据将Kappa系数提高至0.83;WCI提取的建成区轮廓更准确,在增强城乡建成区细部对比、提升边缘地物区分能力方面表现良好,其Kappa系数、查全率、查准率和F1分数均在0.85以上。

住区建成环境对老年人生活品质影响的实证研究--以大连市既有住区为例

伴随着生活圈的不断收缩,住区逐渐成为了老年人日常生活的主要场所,然而,既有住区的建成环境却往往不能满足老年人生活需求,影响老年人的生活品质。研究以大连市既有住区建成环境为对象,基于扎根理论采用拍照、测绘、半开放式访谈的方法,结合文献梳理,分析了住区建成环境对老年人生活品质的影响。研究认为住区建成环境现状问题主要体现于无障碍设计缺失、规划缺失以及管理缺失。这些问题均导致了老年人生活品质下降,且主要体现于无法满足营养需求、安全感需求、卫生需求以及社交需求。因此,为了提高老年人的生活品质,在进行建成环境改造时,应该充分考虑导致老年人生活品质下降背后的动因,并以需求为导向进行统筹优化。研究认为老年人生活品质是一项综合的指标,通过建成环境的优化能够在一定程度上对其进行提升,但只有建成环境与社会环境协同作用,才能更有效的提升老年人的生活品质。

利用珞珈一号提取城市建成区的方法对比分析

采取单独使用珞珈一号(Luojia1-01)夜间灯光数据、构建植被调整NTL城市指数(VANUI)、Luojia1-01和兴趣点(Luojia1-01&POI)指数3种方法提取了2018年成都市的建成区,并利用总体精度和Kappa系数对比了3种方法的提取精度。结果表明,Luojia1-01的高分辨率在建成区提取方面有广阔的应用,但单独使用会产生信息误提的问题;VANUI提取的建成区在内部和边界细节信息方面表现更优,但存在孔隙较多、图斑破碎的问题;Luojia1-01&POI指数提取的建成区范围效果最好、精度最高。研究结果为Luojia1-01与其他类型数据的结合提供了参考,进一步证实了POI数据结合夜间灯光数据提取建成区的高精度与可靠性。

广交会展馆四期扩建工程展厅转换层结构选型及设计若干问题分析

广交会展馆四期扩建工程项目包含展厅及其他功能建筑单体。其中,展厅设缝分为四个分区结构单体,各单体结构平面尺寸均为207m×90m,地上2层、地下1层,主体结构采用钢筋混凝土框架结构,屋盖采用带预应力的倒三角形立体桁架。展厅与地铁28号线隧道、市政隧道(双塔路隧道、会展西路隧道)相互交叉重叠。综合分析地铁线隧道、双塔路隧道多重避让条件、与展厅相对位置关系以及展厅上部使用荷载大等因素,提出交叉重叠区域共建展厅转换层及双塔路隧道结构方案,共建区横跨地铁线隧道以转换展厅上部框架柱。通过对转换层不同结构类型、不同梁截面形式进行比较,以确定最优选型方案,并对整体结构及关键节点进行分析。提出隧道施工盖挖逆作法,针对传统中间桩柱节点存在的弊端,提出利于现场施工、质量保障的改进方案。

城市轨道交通对容积率影响的定量分析——以东京为例

以东京为例研究城市轨道交通对容积率影响的定量关系,可为我国城市轨道交通站区土地资源的合理配置与优化利用提供指导依据。选取区位、建筑类型、到车站距离、地价作为影响地块容积率的因素,并构建了带交互项的线性回归模型进行分析。p值检验结果表明带交互项模型更适用。研究显示“到车站距离”对商业建筑容积率的影响大于居住建筑,商业建筑“核心区”与“到车站距离”间交互影响程度最大,居住建筑“市区”与“到车站距离”间交互影响程度大于郊区。研究结果为调整国内城市轨道交通站区商业建筑物布局,优化城市核心区轨道交通站点周边商业建筑物容积率及调控城市市区与郊区轨道交通站点周边居住建筑物差异化规划提供依据。

日常生活视角下的城市滨河公共空间吸引力影响因素研究——以深圳典型河流为例

滨河公共空间是城市公共空间系统的重要组成部分,展现着城市的形象与特色,是城市居民日常活动的首选地之一。在先前的规划设计中,滨河公共空间的更新改造大多是基于规划从业人员及开发商的专业经验和主观判断进行的,缺乏居民日常生活的视角,缺少对真实需求与行为特征的系统调研,从而制约了规划设计方案的使用满意度。因此,本文从日常生活的视角出发,综合使用定性分析、相关性分析等方法,探究市民行为感知需求与滨河公共空间吸引力提升之间的相关性,发掘影响吸引力提升的相关要素。最终基于上述分析,发现生态景观要素、可达性和环境设施是影响滨河公共空间吸引力水平的三个主要影响因素,并针对三个影响因素初步提出了面向市民日常需求的滨河公共空间提升的策略。

人本视角下多维数字技术在总体城市设计中的集成应用探索--以太原市总体城市设计为例

数据环境和数字技术的协同发展极大地促进了城市设计的技术方法创新,为在城市尺度范围分析人本尺度的高精度数据带来可能。基于空间格局、空间秩序、风貌品质和公共活动等城市设计重点关注领域,对既有城市设计研究中的数字技术进行梳理,构建一个重点适用于存量地区总体城市设计实践的数字技术应用“工具箱”,为城市设计从业人员结合具体现状问题和规划目标,进行定制化的数字技术和多源数据选择提供参考。最后以太原市总体城市设计为例进行数字技术集成应用示范,以期为存量地区城市设计实践提供数字技术应用方面的借鉴。