Remote Sensing &GIS Based Spatio-Temporal Change Analysis of Wetland in Dhaka City, Bangladesh

Landscape of Dhaka city—one of the fastest growing mega cities in the world, is continuously changing due to un-planned urbanization. For example, the wetlands of the city have been shrinking. This study evaluates wetland changes in Dhaka Metropolitan Area (DMA), Bangladesh, between 1978 and 2009. Spatial and temporal dynamics of wetland changes were quantified using four Landsat images, a supervised classi?cation algorithm and the post-classi?cation change detection technique in GIS environment. Accuracy of the Landsat-derived wetland maps ranged from 87% to 92.5%. The analysis revealed that area of wetland and Rivers & Khals in Dhaka city decreased significantly over the last 30 years by 76.67% and 18.72% respectively. This changing trend of wetlands makes the drainage system of Dhaka City vulnerable, creating water logging problems and their consequences. Land filling and encroachment were recognized to be the main reasons for shrinking of the wetlands in the city. Development and alteration of the existing water bodies should consider the natural hydrological conditions.

Analysis of Spatio-Temporal Changes of Land Usein Xuzhou City Based on Remote Sensing

Based on the satellite remote sensing TM/ETM images of Xuzhou city, basic data about land use of the city from 1994 to 2000 are obtained with the neural network classification module of PCI software, and the dynamic con- version matrix of land use is thus calculated. The areas of construction land and water body have increased by 1833.93 hm2 and 804.87 hm2, respectively. On the contrary, the area of cropland has decreased by 3207.24 hm2. The area of cropland converted into construction land makes up 26.84%, and that converted into water body amounts for 8.17% of the total area of cropland in 1994. The variation index of land use degree and the dynamic degree index of land use computed are 1.38 and 57.81%, respectively, which demonstrate that land use in Xuzhou is in a development period and the changes are drastic. The frequency index and importance index of the form in which cropland converted into con- struction land are 29.91% and 68.93% respectively. The results indicate that the change is not only widespread in space but a major form of spatial change of land use in the area.

Analysis of Land Use Change and Driving Force of Bole City Based on Remote Sensing Image

[Objectives] The land use change and its influence has been the frontier and hotspot in the research of the surface process of change. The aim of this study was to provide a reasonable scientific basis for the more reasonable use of regional land resources of Bole City by study of land use change and driving force of Bole City.[Methods] Through geometric correction, image mosaic and image registration processing and classification of the remote sensing images of Bole City in 2006, 2011 and 2016, the three images of land use change in land use types （land use change range, dynamic degree and variation degree） were studied, and the natural and social economy in terms of the driving forces of land use change were analyzed.[Results] In the 2006 to 2016 period, cultivated land of Bole City had the land use dynamic growth state, and the average growth rate was 0.26%; and forest land, construction land, water, grassland and unused land showed a decreasing trend, decreased by 0.23%, 0.22%, 0.75%, 3.85% and 1.52%, respectively. In the entire study period, the change of grassland was the biggest, the changes of unused land and water were the second, and the changes of cultivated land, construction land and forest land were lesser.[Conclusions] The main driving factors that effected on land use change of the study area were climate, industrialization, urbanization, social and economic activities, adjustment of agricultural structure and population expansion.

Characterizing urban expansion of Korla City and its spatial-temporal patterns using remote sensing and GIS methods

Cities provide spatial contexts for populations and economic activities. Determining the spatial-temporal patterns of urban expansion is of particular significance for regional sustainable development. To achieve a better understanding of the spatial-temporal patterns of urban expansion of Korla City, we explore the urban expansion characteristics of Korla City over the period 1995-2015 by employing Landsat TM/ETM＋ images of 1995, 2000, 2005, 2010, and 2015. Urban land use types were classified using the supervised classification method in ENVI 4.5. Urban expansion indices, such as expansion area, expansion proportion, expansion speed, expansion intensity, compactness, and fractal dimension, were calculated. The spatial-temporal patterns and evolution process of the urban expansion （e.g., urban gravity center and its direction of movement） were then quantitatively analyzed. The results indicated that, over the past 25 years, the area and proportion of urban land increased substantially with an average annual growth rate of 15.18%. Farmland and unused land were lost greatly due to the urban expansion. This result might be attributable to the rapid population growth and the dramatic economic development in this area. The city extended to the southeast, and the urban gravity center shifted to the southeast as well by about 2118 m. The degree of urban compactness tended to decrease and the fractal dimension index tended to increase, indicating that the spatial pattern of Korla City was becoming loose, complex, and unstable. This study could provide a scientific reference for the studies on urban expansion of oasis cities in arid land.

Pattern Dynamics of Thermal-environment Effect During Urbanization:A Case Study in Shenzhen City,China

The thermal-environment effect exists in the field of rapid urbanization. It has adverse effects on the urban atmosphere, re- gional climate, energy consumption, and public health. Shenzhen, a representative of rapidly urbanizing cities in China, was selected as a case for pattern dynamics analysis of the thermal environment. The surface temperature was acquired from the thermal infrared data of Landsat TM and ETM＋ images in 1986, 1995, and 2005 by Jim6nez-Mufioz and Sobrino＇s generalized single-channel method, which was used in assessing the distribution and spatial patterns of the thermal environment. The relative thermal environment curve （RTC） was combined with Moran＇s I analysis to assess the pattern dynamics of the thermal environment in different urbanization periods. Moran＇s I index and the RTC represent a process of aggregation-fragmentation-aggregation, which shows the aggregation pattern of a decrease during the rapid urbanization period and then an increase during the steady urbanization period. High-temperature areas gradually ex- panded to a uniform and scattered distribution in the rapid urbanization period; while the high thermal-environment effect was gradually transformed into a steady spatial pattern in the stable urbanization period. To characterize the increasing development in this multiple- center city, we chose profiles along an urban-development axis. The results suggest that heat islands have expanded from internal urban to external urban areas. Four profiles were obtained showing differences in shape due to spatial differences in the process of development.

Dynamic Change Analysis of Urban Green Land in Jinan City Based RS and Geo-information Tupu

The three-period (1995, 1998 and 2003) remote sensing images in Jinan City, China are selected. And the information of green land, construction land, woodland and water body is extracted by using the image processing module of remote-sensing software and computerized interpretation module. Both the change table and transfer matrix table of land use area are analyzed by modeling module of remote-sensing software. Then, the Geo-information Tupu is obtained; and the temporal and spatial variation of land use in Jinan City is monitored and analyzed by Geo-information Tupu and transfer matrix. Result shows that land use structure change of Jinan City in the years 1995-1998 shows a transformation from green land to construction land. Area of green land circulating into construction land reaches 62.27 square kilometers, accounting for 25.84% of the initial green land. In the year 1998, areas of woodland and green land are reduced due to the urban expansion of Jinan City. However, with the enhancement of people's awareness of environmental protection, areas of woodland and green land gradually increase in the year 2003, which are still less than those in the year 1995.

Monitoring of Temporal and Spatial Changes of Land Use and Land Cover in Metropolitan Regions through Remote Sensing and GIS

The use of remote sensing techniques and subsequent analysis by means of geographical information system (GIS) offers an effective method for monitoring temporal and spatial changes of landscapes. This work studies the urbanization processes and associated threats to natural ecosystems and resources in the metropolitan areas of Berlin and Erlangen-Fürth-Nürnber?Schwabach (EFNS). To compute the land use/cover (LULC) of the study areas, a supervised classification of “maximum likelihood” using Landsat data for the years of 1972, 1985, 1998, 2003, and 2015 is used. Results show that the built-up area is the dominant land use in both regions throughout the study period. This land use has increased at the expense of green and open areas in EFNS and at the expense of agricultural land in Berlin. Likewise, 5% of forest in EFNS is replaced with urban infrastructure. However, the amount of forest in Berlin increased by 3%. While EFNS experienced relatively big changes in its water bodies from 1972 to 1985, changes in water bodies in Berlin were rather slight during the last 40 years. The overall accuracy of our remotely sensed LULC maps was between 88% and 94% in Berlin and between 85.87% and 87.4% for EFNS. The combination of remote sensing and GIS appears to be an indispensable tool for monitoring changes in LULC in urban areas and help improving LU planning to avoid environmental and ecological problems.

ANALYSIS OF THE EXPANSION OF THE BUILT-UP AREA OF DALIAN CITY

With the astounding development and gradual improvement of remote sensing technology,as an advanced science technology,it is used to pro vide multi-temporal,large scope re al-time information for land-use dynamic change,and also is one of the best efficient m ethods for studying the earth resour ces and environment.Remote sensing image has its characteristics of ample inform ation and reflecting the objective r ealities.The paper uses multi-temp oral TM images in1986,1996and 2000,and relevant sta tistic data to analyze land-use chan ges of Dalian City in Liaoning Provin ce of Chi-na over ten years by means of the corre lation analysis method.The results have shown that two methods could con-formably reflect the present land-u se change.Urbanization is closely c orrelative to natural factors and ec onomic develop-ment.Especially in recent 20years,under the influence of the reform and open-up policy,Dalian,as a specifi c coast city,is becoming an international m etropolis.

Space Technology for Decarbonising City Precincts

Space technology is a powerful tool for climate research. Satellite data improve knowledge of the human impact on the Planet’s physical geography. Similarly, remote sensing technology enhances understanding of the human impact on rising global carbon emissions. However, so far satellites have been principally limited to measuring the carbon emissions of cities from space. Standing alone, satellite technology is incapable of advancing the goal of decarbonisation. This will be achieved only if cities create local methodologies that significantly enhance the carbon reduction process. There exists enormous potential to bridge remote sensing for earth observation and global environmental change with local action towards decarbonised urban renewal and redevelopment. Satellite remote sensing has the ability to demonstrate if local remedial strategies are succeeding, and assist with planning, developing, and monitoring low and zero carbon infrastructure systems. Satellite-derived data can facilitate informed discussion and decision-making between community stakeholders to deliver low carbon outcomes at the precinct scale. Satellite-based systems can be integrated within the urban fabric to assist climate change mitigation. This paper is based on current work implemented jointly with municipalities to ascertain where within city precincts carbon emissions originate and how they can ultimately be reduced. It presents space technology as an instrumental tool for understanding the carbon impact of cities—in terms of the carbon intensive patterns and processes that shape human society, as well as having great potential for providing end-user products to communities to enhance the process of decarbonising city precincts.

Multi-temporal remote sensing of land cover change and urban sprawl in the coastal city of Yantai, China

The importance of accurately mapping and monitoring land cover changes over time is increasing,especially in rapidly growing coastal cities.In this study,three pairs of Landsat images of Yantai,a representative coastal city in China,from 1989,1999,and 2009 were selected to monitor land cover changes and urban sprawl dynamics.To improve the classification accuracy,three classification methods together with the minimum noise fraction(MNF)and pixel purity index(PPI)calculations were performed on the images.The classification results showed that the overall five-class classification accuracies averaged 91.38%for the 20-year period,which produced an accuracy of 83.78%for change maps.The analysis of change maps indicated that from 1989 to 2009,the percentage of urban area increased from 31.41%to 50.28%of the total area,and the newly urbanized area was mainly located in residential areas and the reclaimed harbor region.Analysis of the relationships between urban area and its driving forces obtained from statistical data found that the urban sprawl of Yantai before 2000 was relatively extensive,which is consistent with the conclusion drawn by using remote sensing techniques.The research results could be used as inputs for sustainable urban management and establishing Digital Earth database.

2000—2021年图木舒克市生态环境质量动态监测与评价

为客观评价新疆图木舒克市驱动因素对其生态环境质量的影响,选取图木舒克市2000、2011年和2021年3期Landsat影像数据,耦合归一化植被指数(NDVI)、土壤湿度(WET)、干度(NDSI)、地表温度(LST)4个指标,分析主成分构建遥感生态指数(RSEI),结合研究区自然因素和社会经济因素,对图木舒克市近22 a来生态环境质量进行动态监测与评价。结果表明:(1)图木舒克市近22 a来RSEI均值从0.406升至0.476,生态环境质量变好面积远大于变差面积,改善区域主要分布在研究区中部、东南、西北地区,近22 a生态环境质量得到有效改善。(2)通过对图木舒克市驱动因素进行分析,当地生态环境质量受人口、国内生产总值(GDP)、耕地面积、气候等因素影响,在驱动因素中社会经济因素对当地生态环境质量有显著影响。(3)通过构建RSEI并分析其驱动因素对生态环境质量的影响,可以高效、准确地对当地生态环境质量进行动态监测与客观评价。

辽宁省资源枯竭型城市转型发展时空动态变化分析

转型发展是资源枯竭型城市实现可持续发展的必由之路。为明晰辽宁省15个资源枯竭城市在辽宁老工业基地振兴关键期的转型发展时空动态演变特征,根据转型发展内涵,从经济发展、民生保障、环境污染治理三方面构建评价指标体系,运用熵值法计算2009—2019年的转型发展分值,ArcGIS 10.2进行空间分析。利用夜光遥感数据验证分析转型发展时空动态演变特征,并对两种方法的分析结果进行空间耦合。结果表明:(1)熵值法和夜光遥感分析结果的空间耦合性总体较好,空间耦合相一致区域占比为73.33%。(2)辽宁资源枯竭地区在10年间的转型发展动态变化率差异较大,葫芦岛市、盘锦市、北票市和葫芦岛南票区的转型发展提升率较高,抚顺市、调兵山市、义县和葫芦岛杨家杖子开发区的提升率较低。(3)资源枯竭城市转型发展中的共性问题是产业转型力度不够,第三产业占比较少;民生发展受下岗职工安置和再就业问题制约;生态环境恢复时间较长,短期内难见明显成效。(4)辽宁资源枯竭城市转型发展均以经济转型为主,民生转型次之,以生态环境转型为辅,多数地区存在发展短板,制约区域转型整体效果。

河南省沿黄地市生态环境质量时空演变及驱动因子分析

黄河流域自然生态本底脆弱,人类长期开发建设活动导致生境破碎化、生物多样性减少。选取2000年、2010年和2020年3期遥感影像数据计算绿度、湿度、干度和热度4个指标,构建遥感生态指数(RSEI),分析河南省黄河干流沿线8个地市生态环境质量时空演变特征及变化趋势,并运用地理探测器分析其驱动因子。结果表明:2000—2020年研究区RSEI平均值为0.7311,生态环境质量整体处于中等偏上水平,灵宝市、郑州市等生态环境质量较差,新安县、孟津区等生态环境质量较好;20 a间研究区生态环境质量先变差后转好,大部分地区呈改善趋势,下游生态环境质量改善情况优于中游;单因子探测结果表明,土地利用类型、国民生产总值等表征人类活动的驱动因子对生态环境质量的影响逐渐增强;多因子交互探测结果表明,国内生产总值、土地利用类型和人口密度与其他各因子的交互作用较强。

基于RS和GIS的康定市地震前后生态环境变化分析

地震及其次生地质灾害对生态环境造成巨大破坏,评价生态环境质量在地震前后变化是对地灾生态修复和寻找应对措施的重要基础工作.基于RS和GIS技术,获取四川省康定市2014年11月22日6.3级地震前后的遥感影像数据并基于主成分分析得到遥感生态指数.根据该指数,得出地震灾害对生态环境质量的影响以及动态变化趋势.结果表明:(1)从地震前后的四个指标变化来看,热度指标与干度指标有轻微变化;绿度指标下降13.64%;湿度指标提升48.39%.(2)从地震前后遥感生态指数变化来看,康定市地震前后生态环境质量以中等及以上为主,分别为86.01%、 75.5%,在地震前后有明显下降.研究结果为康定市地震后生态修复与重建工作提供一定的科学依据.

利用新型遥感生态指数的南宁市环境质量动态变化分析

随着遥感技术的快速发展,利用遥感生态指数(Remote Sensing Ecological Index, RSEI)进行区域生态环境质量监测取得了一定进展,但是RSEI在应用不同区域中很少考虑空气质量对当地生态环境的影响。针对这一局限性,以南宁市为例,在RSEI的基础上,加入能精准监测城区高分辨率空气质量的差值霾指数(Difference Haze Index, DHI),构建新型遥感生态指数(new Remote Sensing Ecological Index, RSEInew),随后对比分析RSEI与RSEInew的平均相关度和PC1,验证了构建的RSEInew模型更具有表征区域生态环境的代表性。利用RSEInew模型对南宁市生态环境质量进行动态变化分析,结果表明,2013—2021年,南宁市生态环境质量得到优化,RSEInew提升了15%,整体生态环境水平处于中等(0.4~0.6)以上。

Evaluation, simulation, and optimization of land use spatial patterns for high-quality development: A case study of Zhengzhou city, China

High-intensity land use and resource overloaded-induced regional land use spatial pattern(LUSP)are essential and challenging for high-quality development.The empirical studies have shown that a scientific land uses spatial layout,and the supporting system should be based on a historical perspective and require better considering the double influence between the current characteristics and future dynamics.This study proposes a comprehensive framework that integrates the resource environment carrying capacity(RECC)and land use change(LUC)to investigate strategies for optimizing the spatial pattern of land use for high-quality development.China’s Zhengzhou city was the subject of a case study whose datasets include remote sensing,spatial monitoring,statistics,and open sources.Three significant results emerged from the analysis:(1)The RECC has significant spatial differentiation but does not follow a specific spatial law,and regions with relatively perfect ecosystems may not necessarily have better RECC.(2)From 2020 to 2030,the construction land and farmland will fluctuate wildly,with the former increasing by 346.21 km^(2) and the latter decreasing by 295.98 km^(2).(3)The study area is divided into five zones,including resource conservation,ecological carrying,living core,suitable construction,and grain supply zones,and each one has its LUSP optimization orientation.This uneven distribution of RECC reflects functional defects in the development and utilization of LUSP.In addition,the increase in construction land and the sharp decline of farmland pose potential threats to the sustainable development of the study area.Hence,these two elements cannot be ignored in the future high-quality development process.The findings indicate that the LUSP optimization based on dual dimensions of RECC and LUC is more realistic than a single-dimension solution,exhibiting the LUSP optimization’s effectiveness and applicability.

基于遥感生态指数的济南市生态环境质量动态监测

城市的快速发展往往会引起生态环境质量的变化,为了促使区域社会经济稳健可持续发展对其生态环境质量评估是非常必要的。以济南市作为研究对象,利用2002—2021年Landsat遥感影像数据,通过计算WET、NDVI、LST、NDBSI,运用主成分分析法对各个分量指标进行分析进而构建RSEI模型。结果表明:(1)2002—2021年济南市RSEI均值分别为0.529、0.502、0.565、0.591,呈先下降后上升趋势,总体处于中等水平;(2)生态环境改善地区主要分布在济南市西北部,生态环境退化地区主要分布在中部、北部、东南部;(3)济南市生态环境变化与NDBSI关系最密切,4年平均相关度为0.715,为进一步分析NDBSI指标对环境质量的影响,对其分量指标IBI和SI指标进行数值分析以及空间分析,IBI指标和SI指标4年平均值为0.565、0.356,通过空间分析IBI指标值较高区域范围与RSEI指标较低区域范围具有高度的吻合度,在NDBSI指标中IBI指标是对济南市生态环境质量产生负面影响的主要因素,表明城镇化的快速发展对生态环境造成一定程度的破坏。

基于ARCGIS和IDRISI的荆州市土地利用变化及其影响分析

以湖北省荆州市为研究对象,基于遥感影像数据和统计数据,采用土地利用类型转移模型、马可夫模型、生态足迹模型和灰色关联度分析等方法,分析了2019—2021年间的土地利用变化特征、驱动因素、影响效应和未来趋势,为该市的可持续发展提供参考。结果表明:①荆州市土地利用变化显著的是建设用地和裸地,体现了该市城市化水平的提升;土地利用变化的主要特征是耕地、湿地和水域减少,而林地和草地增加,体现了该市生态化水平的提高。②荆州市土地利用变化的主要驱动因素是人口增长、经济发展、城镇化进程和政策制度,这些因素通过影响土地利用需求和供给,促进了建设用地的扩张,抑制了耕地、湿地和水域的保持,有助于裸地的改善,支持了林地和草地的增加。科技进步也是一个重要的驱动因素,它通过提高土地利用效率和质量,改善了裸露地表覆盖状况,促进了植被恢复和生态建设。③荆州市土地利用变化对生态环境产生了负面影响。一方面,土地利用变化导致了耕地、湿地和水域等重要资源的减少,降低了生态系统的生产力和稳定性;另一方面,土地利用变化导致了建设用地等高耗能资源的增加,增加了生态系统的负荷和压力。这些影响导致了荆州市生态足迹的增加和生态承载力的减少,造成了生态赤字的扩大和生态失衡的加剧。④荆州市土地利用变化对社会经济产生了正面和负面的影响。一方面,土地利用变化促进了建设用地的增加,提高了经济发展水平和城镇居民生活水平,增强了城市的功能和竞争力。另一方面,土地利用变化抑制了耕地、湿地和水域的保持,降低了农业发展水平和农村居民生活水平,削弱了农业的基础和后盾。这些影响表明荆州市在研究期间存在着城乡发展不平衡的问题,需要协调好城乡之间的关系和利益。

基于遥感生态指数分析太原市城市生态环境质量变化

利用Landsat遥感影像,基于绿度、湿度、干度、热度,构建遥感生态指数(RSEI),定量揭示太原市城六区2004—2020年生态环境质量空间分布与变化,并对其影响因素进行分析。结果表明:2004年、2010年、2020年RSEI均值分别为0.267、0.324、0.345,呈上升趋势,上升速率为0.046/10a,生态环境质量整体向好的趋势发展。太原市城六区生态环境质量呈“川”字形格局,东西部的好,中部的较差,万柏林区在城六区中生态环境质量最好,小店区的最差。土地利用类型改变和人类经济活动是影响生态环境质量的重要原因。2004—2010年生态环境质量改善面积占比达52.50%,2010—2020年51.45%的区域生态环境质量未发生变化,24.89%的区域向好的方向发展;2010—2020年生态环境质量变差面积占比由2004—2010年的9.69%增加至23.66%,因城市发展政策向南倾斜,使生态恶化区域重点向南发展。

局地气候分区体系视角下合肥市昼夜热环境研究

以合肥市主城区为研究区,基于局地气候分区(local climate zone,LCZ)体系,使用Sentinel-2和landset-8影像,分析昼、夜不同LCZ类别间地表温度与城市形态之间的关系,以此研究合肥市地表热环境。结果表明:(1)构建研究区LCZ地图,在两种不同分类中占比最大分别为LCZ9与LCZB/C。(2)不同LCZ类别间的LST存在较为明显的差异,主要体现在建筑类别与自然类别间。昼夜间变化趋势较为一致,且夜间LCZ各类间温度变化幅度小于白天。(3)昼、夜温度温度变化均体现为高层<中层<低层,开阔建筑<密集建筑变化规律。(4)PCC分析表明LST与IBI与MNDWI分别呈现正负相关,相关性较强,且均为r(昼)>r(夜)。