Using negative exponential function to characterize built-up land density along slope gradient for 19 urban areas in China

In China,numerous cities are expanding into sloping land,yet the quantitative distribution patterns of urban built-up land density along the slope gradient remain unclear,limiting the understanding of sloping land urbanization.In this paper,a simple negative exponential function was presented to verify its applicability in 19 typical sloping urban areas in China.The function fits well for all case urban areas(R^(2)≥0.951,p<0.001).The parameters of this function clearly describe two fundamental attributes:initial value a and decline rate b.Between 2000 and 2020,a tends to increase,while b tends to decrease in all urban areas,confirming the hypothesis of mutual promotion between flatland densification and sloping land expansion.Multiple regression analysis indicates that the built-up land density and the ruggedness of background land can explain 70.7%of a,while the average slope ratio of built-up land to background land,the built-up land density and the built-up land area can explain 82.1%of b.This work provides a quantitative investigative tool for distribution of urban built-up land density along slope gradient,aiding in the study of the globally increasing phenomenon of sloping land urbanization from a new perspective.

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.

Analysis of the Relationship between Land Surface Temperature and Vegetation and Built-Up Indices in Upper-Hill, Nairobi

Designing “liveable” cities as climate change effects are felt all over the world has become a priority to city authorities as ways are sought to reduce rising temperatures in urban areas. Urban Heat Island (UHI) effect occurs when there is a difference in temperature between rural and urban areas. In urban areas, impervious surfaces absorb heat during the day and release it at night, making urban areas warmer compared to rural areas which cool faster at night. This Urban Heat Island effect is particularly noticeable at night. Noticeable negative effects of Urban Heat Islands include health problems, air pollution, water shortages and higher energy requirements. The main objective of this research paper was to analyze the spatial and temporal relationship between Land Surface Temperature (LST) and Normalized Density Vegetation Index (NDVI) and Built-Up Density Index (BDI) in Upper-Hill, Nairobi Kenya. The changes in land cover would be represented by analyzing the two indices NDVI and BDI. Results showed the greatest increase in temperature within Upper-Hill of up to 3.96&#176C between the years 2015 and 2017. There was also an increase in impervious surfaces as indicated by NDVI and BDI within Upper-Hill and its surroundings. The linear regression results showed a negative correlation between LST and NDVI and a positive correlation with BDI, which is a better predictor of Land Surface Temperature than NDVI. Data sets were analyzed from Landsat imagery for the periods 1987, 2002, 2015 and 2017 to determine changes in land surface temperatures over a 30 year period and it’s relation to land cover changes using indices. Visual comparisons between Temperature differences between the years revealed that temperatures decreased around the urban areas. Minimum and maximum temperatures showed an increase of 1.6&#176C and 3.65&#176C respectively between 1987 and 2017. The comparisons between LST, NDVI and BDI show the results to be significantly different. The use of NDVI and BDI to study changes in land cover due to urbanization, reduces the time taken to manually classify moderate resolution satellite imagery.

Rainwater harvesting systems: An urban flood risk mitigation measure in arid areas

Rainwater harvesting (RWH) systems have been developed to compensate for shortage in the water supply worldwide. Such systems are not very common in arid areas, particularly in the Gulf Region, due to the scarcity of rainfall and their reduced efficiency in covering water demand and reducing water consumption rates. In spite of this, RWH systems have the potential to reduce urban flood risks, particularly in densely populated areas. This study aimed to assess the potential use of RWH systems as urban flood mitigation measures in arid areas. Their utility in the retention of stormwater runoff and the reduction of water depth and extent were evaluated. The study was conducted in a residential area in Bahrain that experienced waterlogging after heavy rainfall events. The water demand patterns of housing units were analyzed, and the daily water balance for RWH tanks was evaluated. The effect of the implementation of RWH systems on the flood volume was evaluated with a two-dimensional hydrodynamic model. Flood simulations were conducted in several rainfall scenarios with different probabilities of occurrence. The results showed significant reductions in the flood depth and flood extent, but these effects were highly dependent on the rainfall intensity of the event. RWH systems are effective flood mitigation measures, particularly in urban arid regions short of proper stormwater control infrastructure, and they enhance the resilience of the built environment to urban floods.

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。

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。

面向空间使用活动数据的城市建成区碳核算方法研究——以黑龙江省哈尔滨市为例

气候变化是全世界正在面对的重大威胁,实现碳达峰、碳中和目标已成为中国重要的城市发展战略。碳核算是监测城市碳排放情况,调控低碳城市建设的重要技术手段。以城市建成区为碳核算范围,并将城市碳核算方法与城市空间要素相衔接,这对于实现城市“双碳”目标发展具有极强的现实意义。以黑龙江省哈尔滨市为研究对象,总结分析其15年间的能源活动数据与空间使用活动数据,构建城市建成区碳核算体系与面向城市空间使用活动数据的城市建成区碳核算方法,并将核算结果与能源使用碳核算结果进行对比,验证核算方法的准确性。在此基础上,提出构建城市碳中和路径预测、开展低碳城市建设专项评估等碳核算方法应用路径,为国土空间规划助力“双碳”目标的实施提供技术支撑。

Association of tobacco use with the tobacco-related built environment:an ecological study from urban slums of Bhopal,India

Introduction Tobacco is one of the biggest public health problems and a major risk factor for various non-communicable diseases(NCDs).An important aspect of tobacco control strategy could include modifications in the tobacco-related built environment.This study investigated the association between tobacco shop density and tobacco use prevalence in the urban slums of Bhopal city,India.Methods We conducted a cross-sectional survey to obtain the distribution of tobacco-related built environment(tobacco shops)in the neighbourhood(400-m service area)of 32 urban slum clusters of Bhopal.We plotted this distribution using the’network service area analysis’in ArcMap 10.7.1 software.Then,we used an ecological design to determine the association between tobacco shop density and tobacco use prevalence in these 32 clusters(N=6214 adult inhabitants).We used multiple linear regression analysis to estimate the regression coefficient(adjusted for socio-demographic variables)between tobacco use and tobacco shop density at the cluster level.Results The prevalence of tobacco use among all 32 slum clusters ranged from 22.1 to 59.6%(median 40.9%with IQR 31.8-44.2).There were 194 tobacco shops situated in the neighbourhood of all clusters.The median density of tobacco shops was 59.40/km2(IQR 39.9-108.1/km2)in the neighbourhoods of slum clusters.Tobacco use prevalence was significantly associated with tobacco shop density(estimate or B=0.071,p value=0.002)after adjusting for age,literacy,wealth index,and gender ratio.Conclusions Tobacco use prevalence is significantly associated with tobacco shop density in the slums of Bhopal city in central India.We need to develop appropriate built environment interventions to control rampant tobacco use.

轨交站域建成环境评测研究的方向、指标与趋势

建成环境评测是轨交站域城市更新的前提,在新的实践和技术背景下,总结该领域的进展和趋势具有指导意义。从环境行为、指标评价两个方向归纳了轨交站域建成环境评测研究的创新发展与前沿;通过梳理近三十年来的主要文献,探讨了轨交站域建成环境评测指标演进的4个阶段及其特征;最后总结得出认知与评价角度的多元化拓展、评测指标的人本导向与适应性、学科交叉与评测方法的综合化三个方面的研究趋势。

基于混合用地模式识别的济南市老城区典型片区绿色空间降温效应分析

城市绿色空间可以通过生态系统服务调节功能有效缓解城市热岛效应,降低高温健康胁迫风险。城市中心城区特别是老城区建成环境具有高度异质性,复杂建成环境中绿色空间的降温效应,特别是混合用地模式中绿色空间的降温强度、阈值、形状等还需进一步明晰。在厘清城市热环境影响因素和绿色空间降温机制基础上,构建了“冷热岛分析提取-混合用地模式聚类识别-混合用地模式热效应分析-典型绿色空间降温效应分析”的研究框架。针对当前城市绿地指标失实、结构失衡、功能失调等现实问题,选择济南市老城区典型片区进行实证研究,重点分析了中层建筑混合用地模式中绿色空间的降温强度、降温面积阈值、形状及植被覆盖度等,总结了具有高降温效能的绿色空间模式,为促进城市健康人居环境发展提供借鉴。

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。

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。

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。

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。

顾及边缘的多时相SAR图像半监督建筑区提取

针对合成孔径雷达(synthetic aperture radar,SAR)图像中建筑区域难以辨识与标注的问题,提出一种结合改进的伪标签技术和边缘增强策略的半监督建筑区提取新方法.首先,引入同一位置、不同时相的SAR图像作为自然数据增强手段,并通过多个不同时相图像的预测结果投票确定伪标签;其次,设计一种边缘增强辅助模块,通过特征图变形以修正建筑区主体特征,辅以跳跃连接改进边缘特征,并针对主体和边缘特征进行分离式监督;此外,构建一个包含2种传感器和2个城市区域的多时相SAR图像建筑区提取数据集,含1 000幅带标注图像和800组无标注时序图像,并基于该数据集进行实验验证.实验表明,在所构建测试集上,基线方法使用全量数据训练后交并比(intersection over union,IoU)为63.43%,而所提方法在使用10%和全量数据时IoU分别为63.46%和68.24%,仅利用10%的标注数据即可达到基线方法使用全量标注数据训练的精度.

川渝地区天然气管网特征及新建管道项目技术经济评价需求

四川盆地是中国陆上第三大含油气盆地,常规气、页岩气资源量均居全国之首。川渝地区拥有天然气资源禀赋优势,具有巨大的行业发展潜力和空间。为了加快四川盆地天然气产业的发展,对川渝地区天然气管网现状进行调研,以新建管道项目技术经济评价需求为研究对象,提出了川渝管网新建管道经济评价主要影响因素和技术经济特性。研究结果表明:(1)川渝地区天然气管网系统的历史成因有以下3点,即天然气资源分布及开发建设顺序、油气田一体化管理模式的推动及市场的辅助作用;(2)川渝管网的优势有以下4点,即开拓和培育市场、促进利用多元化和产业集群、提高供应安全保障和形成完整发达的产业链;(3)川渝管网新建管道经济评价主要影响因素有以下2点,即蛛网式管网结构是塑造新建管道多元功能的关键因素,投资主体多元化是经济评价反映管道多元功能的主要推手;(4)川渝管网新建管道布局时,应综合考虑企业效益和社会效益,可通过由运输成本决定的用气企业区位论和由投资成本决定的供气点区位论两种方法进行测算。

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。

从夜间灯光数据中提取城市建成区的改进方法

为提高夜间灯光影像中城市建成区的提取精度,对多源遥感数据融合方法进行了改进。以武汉市1992—2020年3类夜间灯光数据为数据源,在调整多源数据融合方法步骤顺序的基础上,加入了突变检测法,从而过滤出影像中较小的建筑物,使其能更好地反映建成区范围。结果表明:①改进方法保留了多源遥感数据融合方法提取的建成区的城市细节,从影像对比图中能明显看出建成区的划分情况;②改进方法的提取精度从85.76%提高至98.84%,能更精确地反映城市建成区范围;③改进方法去除了冗余步骤,提高了研究效率。

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。