Evolution and Simulation of Spatial-temporal Heterogeneities in Ecological Background Quality of Changsha City

By GIS and ENVI,TM/ETM remote sensing images of five districts(Yuelu District,Furong District,Yuhua District,Tianxin District and Kaifu District) in Changsha City center in 2005,2010 and 2015 were interpreted.Moreover,distribution chart for ecological background factors in 2020 was simulated by using CA-Markov module in IDRISI.Using principal component analysis,evaluation model for ecological background quality of the city was established.Via circle analysi s,GS+semi variance function analysis,hot spot area analysis and grey correlation analysis,integrated analysis and evaluation on spatial heterogeneity evolution of ecological background quality in research region were conducted.Results showed that firstly Changsha overall has formed ecological pattern of landscape island city,but ecological background started to show the evolution trend of high heterogeneity and fragmentation under the construction land expansion,and ecological background quality of the city declined from 0.300,6 to 0.257,1 during 2005-2020.Secondly,ecological background quality of Changsha City had typical circle and axial gradient structure,and "eco tone" had the most violent evolution.Thirdly,spatial structure of ecological background quality had region,time and direction heterogeneities,and spatial heterogeneity of region was the most important.Fourthly,hot spot area distribution of ecological background quality evolution showed the "frog jump" trend of gathering in marginal zone and diffusing to peripheral zone.Fifthly,in driving factors of ecological background quality,industrialization rate had the highest grey correlation degree(0.842,1),and grey absolute correlation degree between ecological background quality in Yuelu District and industrialization rate was the highest(0.603,1).

Uncertainty evaluation of the coordinated development of urban human settlement environment and economy in Changsha city

The coordinated development of human settlement environment and economy is of vital significance to urban sustainable development and urban ecosystem health. Urban human settlement and economic systems exist in urban ecosystems, which are a structural complexity. Therefore the research is being challenged by some uncertain factors between human settlements and economic systems. However most of the researches were focused on its determinate objective aspects and qualitative analyses while less concern on the quanti- tative evaluation of coordinated development of urban human settlement environment and economy, especially little on its uncertain aspect. At present, the urgent task is to study the coordinated development of urban settlement environment and economy in terms of the effect of uncertainty. This study analyzed the uncertain characteristics, which would be confronted at different stages, such as confirming the index categories, their bound values, and their construction rate, etc. According to the actual urban conditions, many construction principles based on uncertainties are put forward and an indicating system for human settlement and economic evaluation is established. Moreover, the application of fuzzy mathematics presents a new method and a calculation model for the comprehensive assessment of the coordinated development of urban human settlement environment and economy. The application of the method and model in Changsha city of China showed that the assessment results can reflect not only the overall coordination degree of the city, but also the mode of interactive mechanism between urban economic system and human settlement environment.

Effect of human settlements on urban thermal environment and factor analysis based on multi-source data:A case study of Changsha city

In view of the lack of comprehensive evaluation and analysis from the combination of natural and human multi-dimensional factors,the urban surface temperature patterns of Changsha in 2000,2009 and 2016 are retrieved based on multi-source spatial data(Landsat 5 and Landsat 8 satellite image data,POI spatial big data,digital elevation model,etc.),and 12 natural and human factors closely related to urban thermal environment are quickly obtained.The standard deviation ellipse and spatial principal component analysis(PCA)methods are used to analyze the effect of urban human residential thermal environment and its influencing factors.The results showed that the heat island area increased by 547 km~2 and the maximum surface temperature difference reached 10.1℃during the period 2000–2016.The spatial distribution of urban heat island was mainly concentrated in urban built-up areas,such as industrial and commercial agglomerations and densely populated urban centers.The spatial distribution pattern of heat island is gradually decreasing from the urban center to the suburbs.There were multiple high-temperature centers,such as Wuyi square business circle,Xingsha economic and technological development zone in Changsha County,Wangcheng industrial zone,Yuelu industrial agglomeration,and Tianxin industrial zone.From 2000 to 2016,the main axis of spatial development of heat island remained in the northeast-southwest direction.The center of gravity of heat island shifted 2.7 km to the southwest with the deflection angle of 54.9°in 2000–2009.The center of gravity of heat island shifted to the northeast by 4.8 km with the deflection angle of 60.9°in 2009–2016.On the whole,the change of spatial pattern of thermal environment in Changsha was related to the change of urban construction intensity.Through the PCA method,it was concluded that landscape pattern,urban construction intensity and topographic landforms were the main factors affecting the spatial pattern of urban thermal environment of Changsha.The promotion effect of human factors on the formation of heat island effect was obviously greater than that of natural factors.The temperature would rise by 0.293℃under the synthetic effect of human and natural factors.Due to the complexity of factors influencing the urban thermal environment of human settlements,the utilization of multi-source data could help to reveal the spatial pattern and evolution law of urban thermal environment,deepen the understanding of the causes of urban heat island effect,and clarify the correlation between human and natural factors,so as to provide scientific supports for the improvement of the quality of urban human settlements.

Epidemiologic survey and analysis of mild cognitive impairment amongst community senior citizens of Changsha City

Objective:The purpose of the current study was to conduct a mild cognitive impairment(MCI)prevalence survey among the community senior citizens of Changsha City and analyze possible relevant factors so as to perform early screening and intervention for MCI patients,and delay or prevent MCI from developing into Alzheimer’s disease(AD).Methods:Between April and September 2012,a total of 1764 community senior citizens in Changsha City were selected through multi-stage and random cluster sampling as study subjects.The following tables were used during the investigation to perform preliminary MCI screening for the subjects of this study:a general information survey;Mini-Mental State examination(MMSe);Montreal Cognitive Assessment(MoCA);Beijing version;global Deteriorate Scale(gDS);Clinical Dementia Rating(CDR)scale;and Activities of Daily Living(ADL)scale.Then,neurology specialists made diagnoses according to the actual status of subjects,survey findings,and clinical MCI diagnostic standards.The prevalence of MCI was calculated and the rates concerning senior citizens with different demographic characteristics were compared.Logistic regression analysis was used to analyze relevant factors that led to MCI,and comparing findings with those of other cities was conducted.Results:The MCI prevalence among senior citizens in Changsha City was 16.27%(287/1764).The MCI prevalence increased with age[for the 60,70,and 80 age groups,the prevalence was 9.79%(84/858),20.14%(149/740),and 32.53%(54/166),respectively,P<0.05].The more education received,the less the likelihood of developing MCI[the prevalence of illiteracy,those who went to pri-mary school,junior high school,senior high school,or technical secondary school,college,and un-dergraduates and above was 32.10%(26/81),18.40%(90/489),13.97%(70/501),15.29%(61/399),14.39%(19/132),and 12.96%(21/162),respectively,P<0.05].Bluecollar workers’chances of developing MCI was higher than white-collar workers[19.12%(187/978)and 12.72%(100/786),respectively,P<0.05].Living alone increased the likelihood of developing MCI than not living alone[21.59%(65/301)and 15.17%(222/1463),P<0.05].The logistic regression analysis showed that age,educational background,and marital status were in the regression(P<0.05).The MCI prevalence of Changsha did not differ from that Portugal,Singapore,Beijing,and Urumchi(P>0.05),but lower than Shanghai[35.78%(161/450)]and higher than Chengdu[2.35%(92/3910)](P<0.05).Conclusion:The prevalence of MCI among the community senior citizens of Changsha City is highly related to factors like age,educational background,and marital status.Prevention against these highrisk factors shall be carried out to delay cognitive decline for senior citizens.

Establishment of City Identity System of Changsha of China Based on Characteristic Landscape

Changsha urban landscape had been divided into four categories which were background landscape,contour landscape,architectural and humanity landscape,and garden and green landscape in this paper;and components and characteristics of each landscape had been analyzed in detail,which were used in establishment of city identity system of Changsha.Five subsystems had been taken as contexts and their components were analyzed specifically,which were mind indentify system,visual identity system,behavior identity system,audio identity system and environment identity system.Mind identity system would be disintegrated into characteristic landscape system with urban center as the core,surrounded by natural landscape belt and covering historical deposit.Visual identity system would be constituted through application of city flower,city tree,mascot and standard color.Behavior identity system would be disintegrated into capital of entertainment and behavioral custom of old city.Audio identity system would be decomposed into audio identity of urban streets,of natural landscape and of commercial landscape.Environment identity system would be established from the perspective of ecological environment.It was considered that establishment of city identity system of Changsha could directly promote economic development,and it needed further study on city identity system of Changsha.

Impacts of land-use change on ecosystem service value in Changsha,China

Changsha,a typical city in central China,was selected as the study area to assess the variations of ecosystem service value on the basis of land-use change. The analysis not only included the whole city but also the urban district where the landscape changed more rapidly in the center of the city. Two LANDSAT TM data sets in 1986 and 2000 and land use data of five urban districts from 1995 to 2005 were used to estimate the changes in the size of six land use categories. Meanwhile,previously published value coefficients were used to detect the changes in the value of ecosystem services delivered by each land category. The result shows that the total value of ecosystem services in Changsha declines from $1 009.28 million per year in 1986 to $938.11 million per year in 2000. This decline is largely attributable to the increase of construction land,and the conversion from woodland and water body to cropland to keep the crop production. In the five districts,there is $6.19 million decline in ecosystem service value between 1995 and 2005. Yuelu District has the highest unit ecosystem service value while Yuhua District has the lowest one. This may be attributed to the greater conversion from cropland and grassland to woodland and water body with the increase of construction land in Yuelu District. It is suggested that the increase rate of construction land should be controlled rigorously and the area of woodland and water body should be increased or at least retained in the study area.

城市群规划实施效果评估研究——以长株潭城市群为例

长株潭城市群经济发展对于湖南省以及中国中西部地区的发展至关重要,且该城市群规划实施的效果对其他城市群有重要借鉴意义。基于此,文章根据2000-2017年地级市面板数据,采用合成控制法,评估长株潭城市群规划实施后对城镇化和环境质量的影响。评估分析表明,长株潭城市群规划的实施推动了城市群城乡融合,在一定程度上促进了城镇化的进程,但对环境造成了一定的负面影响,其原因在于长株潭城市群内城市之间的非均衡发展。因此,城市群应着眼于制定合理规划,促进城市均衡发展,重点落实城乡融合和生态文明;各级政府应加强公共治理,强化监督和治理责任,以更好地实现城市群规划的既定目标。

Research on Traffic Accessibility and Transportation Integration Level of Chang-Zhu-Tan City Group in China

Aiming at the problem of lack of data model to analyze the level of transportation integration, the paper taking Changsha-Zhuzhou-Xiangtan City Group of China as the research object, based on the Gravity measurement model, transportation comprehensive distance model, weighted road density model, analysis of Changsha-Zhuzhou-Xiangtan City Group accessibility and transportation integration level. A new method to measure the level of traffic integration is proposed and verified by the road network data and socio-economic data of Changsha-Zhuzhou-Xiangtan City Group. The results show that: Changsha-Zhuzhou-Xiangtan City Group traffic accessibility was “point to surface” shape distribution, taking the core region of Changsha as the optimal, Xiangtan, Zhuzhou, Changsha County next, in remote Yanling County, Chaling county has the lowest accessibility;the correlation between traffic network connection degree and economic connection degree reached 0.871, indicating that the transportation integration level of urban agglomerations has a high degree of fit with the level of economic integration. The research results on the one hand for the Chang-Zhuzhou-Xiangtan urban agglomeration traffic present situation to make an annotation;on the other hand, that provide a reference for further optimization of Changsha-Zhuzhou-Xiangtan urban agglomeration traffic planning.

长沙城市绿地森林与草地土壤呼吸及温度敏感性变化特征

城市绿地在减缓城市碳排放和温室效应中发挥着巨大作用。土壤呼吸是城市绿地碳循环的重要环节,决定着生态系统碳汇功能的强弱。以湖南省长沙市远大城园区内森林和草地生态系统为研究对象,于2021年11月—2022年12月对土壤呼吸速率及土壤环境进行监测,并结合2022年发生的极端干旱事件,分析城市绿地森林与草地生态系统土壤呼吸特征及其对极端干旱的响应。结果表明:森林和草地生态系统土壤呼吸速率总体呈现出夏秋季(231.98、239.33 mg·m^(-2)·h^(-1))>冬春季(179.28、91.15 mg·m^(-2)·h^(-1))(以C计);极端干旱下土壤呼吸变化显著,在森林生态系统中更加明显;年尺度下,森林和草地生态系统土壤碳排放量分别为681.55、564.66 g·m^(-2)·a-1(以C计);森林和草地生态系统土壤呼吸温度敏感性系数(Q 10值)的范围分别为0.81~1.06、1.19~1.80,草地生态系统对温度变化的响应更敏感,在极端干旱气候条件下可能会导致更多的土壤碳流失。研究结果可以为城市绿地建设和城市“碳中和”目标的实现提供科学依据。

长沙“网红城市”形象的传播策略研究——基于抖音短视频数据分析

“网红城市”是城市空间与城市形象在新媒介传播中的时代标签。近年来,长沙丰富的媒介资源尤其是短视频凭借传播速度快、用户基数大、社交属性强等特点为构建“网红长沙”空间形象提供了前所未有的媒介语境。本文对抖音平台有关长沙点赞量top60的视频文本展开分析发现:长沙以娱乐消费属性为主,历史文化属性次之的形象呈现;长沙城市形象传播中出现内容同质化、泛娱乐化、内容关注度两极分化等问题。为此本文提出叙事优化、特色挖掘和文化聚焦的改善路径,以此构建人文性、多元化和创新性的“网红长沙”城市形象。

2012—2022年长沙市水痘暴发疫情流行特征与处置情况分析

目的分析长沙市水痘暴发疫情流行特征与处置情况,为针对性开展水痘防控提供参考。方法收集2012—2022年长沙市各区(县、市)疾病预防控制中心上报的水痘暴发疫情流行病学调查与处置资料,对水痘暴发疫情的三间分布特征以及暴发疫情的班级聚集性情况、病例疫苗接种情况、报告时间间隔、疫情规模等暴发处置信息进行分析。结果2012—2022年长沙市共报告水痘暴发疫情101起,报告病例3236例,无死亡病例。10—12月是水痘暴发疫情高发期,报告疫情数占全年的62.38%(63/101)。浏阳市暴发疫情数和发病数占比最高,分别为56.44%(57/101)和53.86%(1743/3236)。暴发疫情发生场所主要为小学,报告疫情数和病例数占比分别为78.22%(79/101)和83.16%(2691/3236)。发生在学校的100起水痘暴发疫情中,聚集性班级占比为13.07%(325/2431),其中托幼机构聚集性班级占比较高(21.51%,37/172);有57起调查了疫苗接种情况,病例疫苗接种率为27.63%(454/1643)。暴发疫情的病例中位数为27(19,38)例,首例病例发病至疫情报告时间间隔中位数为17(8,21)d,疫情持续时间中位数为32(20,49)d。2012—2022年首例病例发病至疫情报告时间间隔和疫情持续时间总体呈增长趋势(Z=2.516、2.606,P均<0.05)。结论长沙市水痘暴发疫情呈先升后降趋势,小学为重点发病场所,病例疫苗接种率较低,疫情报告时间间隔和持续时间总体呈增长趋势,今后应进一步提高疫苗接种率,并提高疫情早期发现能力和报告及时性。

人群感知视角下的城市沿街绿道选线方法研究

城市沿街绿道建设对于城市高密度环境改善与居民生活品质提升具有显著作用。当前,城市沿街绿道多以道路与居住区、公共绿地之间空间关系等因素为基准开展选线,缺乏对街道空间品质、居民感知等多维度因素的系统化考虑。本研究从城市感知视角出发,利用街景图像分割技术、空间分析方法等,选取居民对路网的多维感知特征以及道路与公共服务设施空间位置关系特征,构建沿街绿道潜力评价指标体系,形成沿街绿道选线方法。本研究以长沙市主城区为实证案例,研究结果表明:(1)长沙市绿道潜力在城市边缘区域呈现高值集聚,核心区域呈现低值集聚特征;(2)结合绿道潜力和连通性,选取出19条新增绿道,构建市域—社区2级连续型城市沿街绿道网络体系,以改善现有绿道的公平性以及与城市生态系统服务能力。

长沙夏季大气非甲烷碳氢污染特征及来源解析

非甲烷碳氢(NMHCs)是臭氧等二次污染重要前体物.选择长沙市2个城市站(W和S点)于2017年夏季采集了大气NMHCs样品.结果显示,观测期间长沙市NMHCs平均体积浓度为(8.67±3.62)×10^(-9)(W)和(12.30±6.01)×10^(-9)(S).烷烃是最主要组分,贡献了64.7%(W)和60.5%(S);其次是芳香烃,占比21.6%(W)和24.4%(S).浓度组成及比值日变化特征表明W点NMHCs浓度上午高于下午,主要受机动车排放影响;S点则是早晚高中午低,可能与中午光化学反应强、早高峰机动车排放大等有关.芳香烃是最重要的活性化合物,贡献了53.9%—56.0%的臭氧生成潜势;异戊二烯和烯烃对等效丙烯浓度的贡献也较大(合计>40%).长沙市夏季大气NMHCs来源主要有汽油车尾气(25.0%)、工业过程与溶剂使用(20.2%)、生物质燃烧与天然气使用(19.8%)、汽油挥发(17.2%)、柴油车尾气(12.3%)和植物排放(5.5%).不同站点来源存在差异:W点受汽油车尾气影响最大(30.2%),其次是生物质燃烧与天然气使用(22.6%);而S点主要受工业过程与溶剂使用(23.9%)和汽油车尾气影响(20.2%).

基于DPSR模型的城市水安全评价与保障能力提升

水安全评价是水资源开发利用与保护的基础,提升城市水安全有利于促进生态环境保护,支撑经济社会高质量发展。基于驱动-压力-状态-响应(DPSR)模型构建以资源安全、社会安全和经济安全为核心的水安全评价指标体系,运用熵权法确定指标权重,以长沙市为实例,对“十三五”期间城市水安全状况进行评估与分析。结果表明:长沙市水安全状况尽管从2018年“不安全”等级提升至2020年“安全”等级,但状态不稳定,进而制定了加强保水工程建设、提升水环境质量、加强水灾害防治能力3个方案,综合考虑方案投入成本并对比水安全提升效果,给出了先后实施方案2—方案1—方案3的长沙市水安全提升优化路径。

基于POI数据的城市活动设施空间格局研究——以长沙市为例

城市活动设施的空间格局研究可为完善城市布局、优化城市空间结构提供理论和实际参考。基于POI数据,运用核密度估计法、平均最近邻指数法、标准差椭圆、叠加分析等方法,综合探究长沙市活动设施空间格局。结果表明,(1)长沙市主城区活动设施中心呈“一主多副”特征,“主中心”边界范围广,集聚优势显著,功能设施混合度高。(2)长沙市居民的活动区域,东城区比西城区聚集程度更高。(3)城市居民活动空间沿“东北-西南”轴方向发展,与流经长沙市的湘江段走向相同。依据研究结论,提出城市活动设施空间结构优化建议。

城市高质量发展背景下长沙宜居性评价

高质量发展就是要满足人民日益增长的对美好生活的需求,构建宜居城市,对提升城市居民的生活品质具有重大的实践意义。选择长沙市为案例,从创新、协调、开放、绿色、共享、经济6个层面选取了24项具体指标,结合熵值法、 ArcGIS等方法和软件,对长沙9个区县的宜居现状进行了分析,并探究其影响因素。结果表明,长沙城市宜居性整体水平较高,呈现“中间高两周低”的空间分布格局,其中,芙蓉区、望城区、开福区、岳麓区形成了主要核心区向四周辐射递减;从各个维度而言,宜居性呈现较强的空间分异,不同行政区在不同准测层下的宜居水平具有很大差别;长沙市宜居性空间格局与经济发展、开放发展、绿色发展具有较强的关联性,而协调发展、共享发展和创新发展的解释力则相对较弱。基于此,从宏观指引和微观行动层面提出政策建议。

2013—2022年长沙市6岁及以上人群手足口病流行特征分析

目的了解湖南省长沙市6岁及以上人群手足口病流行特征,为手足口病防控提供科学依据。方法通过中国疾病预防控制信息系统获取2013—2022年长沙市手足口病报告病例基本信息,同时收集各县(市、区)手足口病病原学监测数据。采用描述流行病学方法分析病例三间分布及病原构成变化。结果2013—2022年长沙市累计报告6岁及以上人群手足口病病例14889例,占手足口病总病例数的5.04%,无重症和死亡病例报告,年均报告发病率为19.54/10万。2013—2022年该人群病例在总病例数中的构成比总体呈上升趋势(χ^(2)_(趋势)=1658.760,P<0.01),每年发病主高峰出现在4—7月。性别分布上,男性8526例,女性6363例,性别比为1.34∶1;年龄中位数为7(6,10)岁,最大年龄为91岁,年龄分布以6~15岁为主,占88.09%(13116/14889);职业分布以学生为主,占55.97%(8334/14889)。城区(雨花区、开福区、岳麓区、芙蓉区和天心区)的年均报告发病率为24.70/10万,高于郊区(长沙县、浏阳市、宁乡市和望城区)的年均报告发病率(12.75/10万)。病原学监测结果显示,送检标本的肠道病毒阳性率为50.49%(156/309),其中肠道病毒A组71型(enterovirus A71,EV-A71)、柯萨奇病毒A组16型(coxasckievirus A16,CV-A16)和其他肠道病毒的构成比分别为5.77%(9/156)、37.18%(58/156)和57.05%(89/156)。结论2013—2022年长沙市手足口病病例中,6岁及以上人群占比总体呈升高趋势,以其他肠道病毒为主。建议密切关注6岁及以上人群的手足口病预防工作,加强中小学校手足口病防控措施,同时做好其他肠道病毒分型监测工作。

疫情影响下长沙市某污水处理厂水量水质统计分析

为保障城市污水处理厂的安全运行和达标排放,文中选取长沙市某污水处理厂近6年进水水量和进出水水质数据进行统计和分析。结果表明:该污水处理厂的日均进水量在2018年—2023年3月近6年期间,于2020年达到最低,主要是受2020年年初新冠疫情所采取的封控措施影响;当年的进水水质受疫情和降雨量的双重影响,除2022年外,2020年BOD_(5)、COD_(Cr)和SS浓度较其他年份均大幅下降,而氨氮、TN和TP浓度降低相对较小。2022年进水BOD_(5)和SS低于其他年份可能是受2022年相对严重的疫情和干旱天气的影响,管道中污染物沉积进行厌氧水解导致。以疫情初始的2020年数据为研究对象,该年内各水质指标的进水浓度波动范围较大,总体上在冬季相对较高,在1月底—2月底和夏季偏低。实测出水水质浓度均达到设计出水水质标准,其中SS的去除率最高,而TN的去除率最低,改良式序列间歇反应器(MSBR)能够去除大部分的TN和氨氮。进水BOD_(5)/COD_(Cr)、BOD_(5)/TN和BOD_(5)/TP的平均值分别为0.58、4.95和46.34,1月底—2月底受疫情影响出现短暂的急剧变化,但总体进水可生化性较好、碳源充足,可采用生物除磷工艺。在碳源不足时,为保证出水达标,可考虑化学辅助除磷。研究结果可为疫情影响下类似污水处理厂的设计和运行提供参考。

长沙老城区城市更新模式与规划策略研究

城市更新研究多以局部地段为案例,以整个“老城区”或“历史城区”为案例的研究较少。以长沙老城区为研究对象,首先,归纳并分析了老城区城市更新面临历史保护、功能疏解、业态升级、设施老化、拆迁安置和政策体制等突出问题。其次,基于老城区现状特点,提出了老城区城市更新的总体目标与专项目标,梳理了适应老城区城市更新不同类型的技术模式为微改造、综合整治、环境提质、拆除重建四类,运作模式为政府主导、开发商主导和多元主体合作三类。最后,基于多种因素考虑,因地制宜地将老城区划分为多个城市更新单元,并从整体保护、空间优化、城市活力和公众参与等方面提出了长沙老城区城市更新的规划策略。