Rapid economic and social development in the Yongding River basin has resulted in a considerable increase in water consumption, and the Beijing section of the Yongding River has been continuously cut off since 1997, causing the water ecosystem to be seriously degraded.Since 2019, an ecological water supplementation project for the Yongding River has been implemented to repair its ecosystem.Water quality changes in the Yongding River after ecological water supplementation are an important aspect of the comprehensive evaluation of the effect of the project in the Beijing section of the river.In this study, we use Sentinel2-MSI satellite remote sensing data to determine the water transparency and chlorophyll-a concentration of the Beijing section of the river in the summers of 2018, 2019, and 2020, and to analyze the spatial and temporal changes in water quality after the ecological water supplementation of the river in the spring of 2019.Compared with the values from 2018 before the ecological water supplementation, the transparency increased and the water was more limpid in 2019 and 2020 after the ecological water supplementation; the concentration of chlorophyll-a decreased, and the degree of eutrophication was reduced; variations in these water quality parameters illustrate that ecological water supplementation improved the ecotope of the Beijing section of the Yongding River.

Due to the overexploitation of water resources, ground subsidence is becoming increasingly problematic in Beijing, China's political, economic, and cultural capital. This article aims to investigate the relationship between ground subsidence and changes in groundwater depth, and water supply from a long-term point of view. Multisource synthetic aperture radar (SAR) data using the interferometric SAR (InSAR) technique were adopted in this research, combined with a set of leveling and ground subsidence data in the Beijing Plain area from 2003 to 2020. The InSAR results demonstrate that ground subsidence in the plain area increased steadily from 2003 to 2015, expanding from sporadic to continuous laminar dispersion and producing five major subsidence centers. The South-to-North Water Diversion Project (SNWDP) that was completed in 2008 and 2015 considerably reduced the demand for groundwater supply in the Beijing Plain area. Since then, the groundwater level depth has continued to increase. However, since 2016, the ground subsidence rate has dramatically slowed down. The obtained results showed that, thanks to the SNWDP, which resulted in a decline in groundwater exploitation and an increase in renewable water recycling, the ground subsidence in Beijing's plain area has been effectively managed.

Illegal construction has seriously affected the appearance of the city and the lives of residents.In order to effectively monitor and discover illegal construction,this paper explored and practiced the key technology of illegal construction monitoring based on street view data,and carried out a demonstration application in Beijing,forming the following research results:① the technology of street view technology was developed in monitoring illegal construction Process;②deep learning technology was integrated to develop an automatic recognition algorithm for changing buildings in street view,design the layout format of the change map and propose an automatic generation algorithm for the change map;③Combining geographic information system(GIS)technology,an on-site inspection of illegal construction integrated with internal and external industries business process was formed to realize the whole process monitoring of illegal construction from discovery to demolition;④the street view violation inspection system was researched and designed to carry out practical application in the special action of"decommissioning,rectification and promotion"in Beijing.The key technology research and application demonstration in this paper have important technical support for improving the construction of the city's ecological civilization and the spatial governance of the city's appearance and city appearance.

Change detection using high-resolution remote sensing images provides crucial information for geospatial monitoring, which is of great importance as urbanization continues.However, current deep learning models for change detection tasks are mostly based on convolutional neural networks (CNNs), from which it is difficult to extract global information owing to the locality of convolution operations.In this paper, we propose a deep learning model, Siam-Swin-UNet (SSUNet), for remote sensing change detection.SSUNet is designed following the classic UNet-like encoder-decoder framework but has three major innovations: (1) The encoder and decoder are pure transformer-based and hierarchically structured, which avoids the locality problem of CNN but retains the capability of hierarchical representation.(2) The encoder incorporates the Siamese structure, which can process bi-temporal remote sensing images in parallel, and to which is added a fusion module to properly fuse the feature maps extracted from the Siamese structure.(3) The backbone of the SSUNet is Swin Transformer V2 blocks, which can be more stable in further applications of the model, such as transfer learning or scaling up of the model capacity.We experimented with the proposed SSUNet on the LEVIR-CD dataset, along with CNN-based models such as UNet, UNet++, FC-Siam-Conc, and FC-Siam-Diff.The results showed our model outperformed the CNN-based models by a large margin based on evaluation metrics including precision, recall, F1-score, and overall accuracy (OA).Moreover, we conducted ablation studies to further prove the effectiveness of the Siamese structure and the choice of the backbone.The proposed SSUNet has great potential for use in remote sensing change detection tasks.

本文利用北京市2015、2017及2019年三期地理国情普查及监测数据,分析了北京市生态保护红线内地表覆盖空间变化特征,并在全局及局部Moran's I空间自相关分析的基础上,从空间上对生态保护红线内生态修复显著、生态破坏显著区域进行识别.研究结果表明,2015—2019年,生态保护红线内的生态用地整体处于流出状态,且各类变化斑块间存在明显的空间自相关效应,15个区域为人类活动密集区,其中雾灵山及周边山区、松山及玉渡山保护区、南海子公园、密云水库、怀沙怀九河、泃河平谷段(西南段)等6个地区为生态破坏显著区域,建议对其加大监管力度;生态修复显著区域为京密引水渠密云段,其他8个区域均为人为破坏及修复活动共存区域.本文为严守生态保护红线,加快建设美丽北京及生态文明建设提供决策依据,同时也适用于全国其他地区生态保护红线内地表覆盖变化的监测.

目前,第五代移动通信技术(5th generation mobile communication technology,5G)技术想要全面推广,需要做好基站选址的工作.5G信号频率较高,穿透能力与4G、3G、2G相差悬殊,利用传统的基站布设策略,无法保证室内深度覆盖需要的良好体验.针对这一问题,本文首次基于自动化重建的室内模型进行了5G信号仿真,并提出了5G小基站选址的优化方法.首先确定候选基站,模拟5G信号传播过程;然后考虑信号传播过程中的路径损耗和墙面材料对信号造成的反射衰减损耗,以模拟5G信号的强度值和覆盖度.最后基于重建的室内结构化模型与5G信号仿真结果,利用贪婪优化算法设计了面向5G基站优化选址策略.实验结果表明,本文的方法能够有效地模拟5G信号,并且实现自动化5G基站布设和选址,该方法能更好地满足室内快速布设大量高密度5G通信基站的需求.

针对目前研究仅定性或半定量地评价流域内不同用地类型对地表径流的影响程度,难以定量地分析城市下垫面对降水蓄滞效能高低的问题,该文以2015、2020年北京市城市下垫面数据为基础,结合当年的降雨量,从地表综合径流系数和蓄滞效能两个方面,评估了城市下垫面的综合蓄滞效应.结果表明:北京市的下垫面综合径流系数存在空间分异,从低值聚集区到高值聚集区呈现出由外向内的空间聚集分布特征,全市雨水径流的滞蓄率约为65.9％.该文定量分析了城市下垫面对降水的蓄滞效能,对城市内涝预警,发挥蓄滞空间控制雨水径流作用具有现实意义,可在其他大城市蓄滞效能的研究中推广应用.

根据国务院的相关要求,全国各省市已经圆满完成了第二次全国地名普查任务,建设了国家地名信息库,并科学有序地推进地名普查成果转化利用工作.当前,北京市正处于成果转化利用尾声,开展了年度地名信息数据采集更新工作.文章基于北京市地名信息数据采集更新项目,建立地名信息数据共享交换机制,研究地名信息数据采集更新基本原则,总结地名信息数据更新方法,形成北京市地名更新标准目录,探索了北京市地名信息数据采集更新机制,为北京市地名管理以及国家地名信息库更新完善提供思路.

The preventive monitoring and sustainable conservation of large-scale cultural heritage sites require satellite-based Earth observations. In this study, we present the first monitoring and thematic mapping results of the Badaling Great Wall (Beijing, China) using deformation indicators calculated from very high-resolution (VHR) multi-temporal spotlight TerraSAR-X data. The proposed coarse–fine search algorithm achieved high computational efficiency for calculating the unknown parameters of the two-tier network persistent scatterer synthetic aperture radar (SAR) interferometry (PSInSAR) approach. The spatiotemporal deformation anomalies, characterized by the absolute velocity, deformation deviation and acceleration, are informative to identify suspected hotspots for prioritizing monitoring activities. We provide an understandable method for thematic mapping and subsequent sustainable conservation of heritage sites by synergistically exploiting impacts from natural degradation and the tourism industry. We determine that the optimum tourist capacity of the site could be 1.0 million per month based on comparing pre- and post-COVID data (2019–2020). This study demonstrates the potential and performance of spaceborne PSInSAR tools for the intelligent management of large-scale architectural heritage sites by integrating InSAR deformation products with environmental and social data.

针对保障生态保护红线精准落地、服务国土空间规划问题,该文基于北京市生态保护红线评估工作实践,以国土空间规划为视角,提出生态保护红线成效评估指标,分析了北京市生态保护红线校核前后边界规则程度、地表覆盖以及与自然保护区协调程度的变化.研究结果表明,北京市生态保护红线校核后边界复杂程度降低;房屋建筑区、构筑物、人工堆掘地、铁路与道路、种植土地均有所减少,荒漠与裸露地表基本没有变化,林草覆盖、水域明显增加;自然保护区各功能分区面积都有所增加.在今后生态保护红线动态更新过程中要全面掌握空间规划需求,推进"多规合一"实施,实现全市"一张图".

无人机倾斜摄影实景三维技术为智慧城市的快速推进提供了支撑,三维模型精度对应用效果和建模过程均有重要影响,本文从控制点数量、控制点分布以及航线布设三个方面开展精度验证工作,以北京怀柔某区为研究区,设置3组对比实验,选取14个检查点对各组实验进行精度评定.结果表明,满足产品规范精度要求且最经济的方案为单向航线、5个控制点且保证四角分布的方案;控制点分布相较于控制点数量对模型精度的影响更大;增加交叉航线可一定程度提升平面精度.研究结果可较为系统地为实际应用工作提出指导和建议.

六世班禅是清代唯一东来朝觐的班禅活佛,其朝觐之行促进了中华民族的大团结和多民族国家的巩固和发展,具有深远的历史意义.以往的研究中存在对历史路线研究较少、无坐标位置、无电子地图、路线粗略、缺少古今地名对照等问题.针对以上问题,利用文本空间化、Cesium三维可视化等技术,在充分参考历史地图的前提下,结合OpenStreetMap路网进行路线信息挖掘及路线制作;并利用三维地形图、影像等数据,对路线进行修改和佐证,进一步细化了六世班禅朝觐与灵柩西归的路线;最终制作了坐标精确、具有古今地名对照的六世班禅朝觐与灵柩西归路线电子地图,填补了以往研究的空白.制图成果在故宫博物院《须弥福寿——当扎什伦布寺遇上紫禁城》文物展上进行展出,使用的方法在其他历史路线研究中具有借鉴意义.

针对特大城市在发展过程中出现的人口拥挤、交通拥堵等“城市病”问题,“城市体检”模式被正式提出.该文通过对“城市体检”的内涵、体系构建、内容设计及应用方面的全面阐述,集中体现了“城市体检”的核心思想,即通过多元城市现状数据的获取与感知,基于业务模型的智能化计算,实现城市现状状态的反馈,发现城市管理痛点,并为最终解决城市管理问题提供信息决策.通过在北京市市级、区级、街道级等多个层次的深入应用发现,基于空间大数据的“城市体检”模式能够评估现状公共服务能力、解决城市公共管理问题,但仍需要在城市区域现状数据感知和业务模型精确度上提高体检能力.

为了实现京津冀协调发展战略,北京市近年实施了"疏解整治促提升"行动.然而,由于历史原因,违法用地和违法建设(简称"两违")长期存在,"两违"的发现、定位、核验以及监测预警难度较大.在国家自然科学基金项目、北京市自然科学基金重点项目以及北京市多项重大专项工程的支持下,北京市测绘设计研究院联合北京建筑大学、北京英泰思迪空间信息技术公司等有关单位,采取"政产学研用"结合、多学科综合交叉的方式,通过综合运用先进遥感、移动道路测量、人工智能、众源数据挖掘、时空分析等新技术,融合多源数据多种技术手段研究"两违"全流程发现-核查-监测预警的监管关键技术、机制与工艺流程(图1),服务于北京城市总体规划,为北京市"疏解整治促提升"行动计划提供了智能化技术手段,为政府决策提供了精准的信息支持.

当前第二次全国地名普查成果转化工作已进入尾声阶段,信息化建设是普查成果转化的重要途径之一。本文介绍了北京市地名信息化工作各个阶段建设的主要成果,研究了地名信息化建设特点,为地名管理与服务提供支持,进一步推动北京市智慧城市的建设。

本文基于地理国情监测数据,结合同期城市经济、人口等统计数据,利用高分辨率卫星遥感影像数据提取北京市建成区边界要素.采用地理国情与城市空间扩展相融合的监测分析模型及相关评价指标开展空间格局变化分析研究,揭示北京市2000—2017年间城市扩展的空间格局及其变化规律,并对其变化原因进行分析.其成果可为北京市科学规划与可持续发展提供决策依据.

城市无障碍设施在区域空间中往往呈现聚集分布的特征,通常利用核密度估计方法分析总体空间分布形态,研究区域空间分布的数量差异,探测分布热点;同时通过分析无障碍设施空间自相关性特征,反映无障碍设施服务的聚集特点.将空间分析方法引入到无障碍环境评估当中,可以优化无障碍环境发展空间.结果 表明,北京市核心区无障碍设施总体呈现出"多核分布"的态势.无障碍设施的总体分布存在空间差异性,局部无障碍设施空间分布存在聚集特性.

历史文化街区及其房屋建筑是重要的历史文化资源,需要有效的保护和利用;同时又是城市的有机组成部分,需要持续的更新和发展.本文从历史街区保护的角度着眼,以北京市老城范围内历史文化街区建筑物肌理及第五立面特征为研究内容,对建筑物的第五立面色彩及形态特征、临时建筑的分布及演变等进行了分析.加强对第五立面的规划管控,在对历史文化传统风貌保护、实现旧城有机更新,提高北京老城居住环境和生活品质的目标等方面发挥作用.

基于倾斜摄影可以快速获得高精度的城市实景三维模型,分析了实景三维模型数据的特点,探讨了实景三维模型数据质量检查的重点内容和质量元素,结合北京市大规模倾斜摄影实景三维数据质量检查实例,对实景三维数据质检问题与内容进行了总结,最后提出了实景三维模型数据的质量检查方法.

本文首先对公共设施服务能力评估的应用方向和主要方法进行了阐述,并具体介绍了两步移动搜索法.然后以北京市为研究对象,结合教育设施的特点,以实际案例证明了该方法的有效性.研究重点考虑了针对不同研究区域的合理阈值计算模型,可以更好的反映不同区域的教育设施供给变化,对未来教育规划提供依据.