Urban Expansion of China from the 1970s to 2020 Based on Remote Sensing Technology

Based on Remote Sensing (RS) and Geographical Information System (GIS) technology,urban expansion of 75 cities in China from the 1970s to 2020 was reconstructed by visual-interpretation method,which described the growing process of urban lands and its influences on local land use structures synchronously.By employing annual expansion area per city and urban expansion density,spatial-temporal characteristics and macro patterns of urban expansion were analyzed from the aspects of regional-distributions,administrative-levels and population-sizes comprehensively.Results indicate that:1) urban expansion in China was universal,distinct,persistent,periodic and fluctuating.In the past five decades,urban lands of 75 monitored cities in China expanded dramatically from 3606.26 km2 to 30 521.13 km2.2) Though urban expansion presented significant differences from the aspects of regional distribution,administrative levels,and population sizes,it exhibited a deceleration trend in the 13th Five-Year Plan among all kinds of cities.3) Cultivated lands were the first land resource for urban expansion,and 55.17% of newly-expanded urban lands appeared by encroaching this land use type.China’s urban expansion has caused sustained pressure on cultivated land protection,especially in super megacities,and the contradiction between urban expansion and cultivated land protection will always exist.4) The compactness of urban lands in China increased before 1987 and reduced in the next three decades,which was consistent with the implementation of major policies and the deployment of national strategies,and is expected to become compact with a stopping declining or even rebounding after the 13th Five-Year Plan.

Land Use/Land Cover Change Detection in Pokhara Metropolitan, Nepal Using Remote Sensing

Land use and land cover are essential for maintaining and managing the natural resources on the earth surface. A complex set of economic, demographic, social, cultural, technological, and environmental processes usually result in the change in the land use/land cover change (LULC). Pokhara Metropolitan is influenced mainly by the combination of various driving forces: geographical location, high rate of population growth, economic opportunity, globalization, tourism activities, and political activities. In addition to this, geographically steep slope, rugged terrain, and fragile geomorphic conditions and the frequency of earthquakes, floods, and landslides make the Pokhara Metropolitan region a disaster-prone area. The increment of the population along with infrastructure development of a given territory leads towards the urbanization. It has been rapidly changing due to urbanization, industrialization and internal migration since the 1970s. The landscapes and ground patterns are frequently changing on time and prone to disaster. Here a study has been carried to study on LULC for the last 18 years (2000-2018). The supervised classification on Landsat Imagery was performed and verified the classification through computing the error matrix. Besides, the water bodies and vegetation area were extracted through the Normalized Difference Water Index (NDWI) and Normalized Difference Vegetation Index (NDWI) respectively. This research shows that during the last 18 years the agricultural areas diminishing by 15.66% while urban area is increasing by 13.2%. This research is beneficial for preparing the plan and policy in the sustainable development of Pokhara Metropolitan.

Urban Expansion and Its Influencing Factors in Natural Wetland Distribution Area in Fuzhou City,China

This paper principally focuses on land use dynamics,urban expansion and underlying driving forces in the Natural Wetland Distribution Area(NWDA)of Fuzhou City in the southeastern China.Based on time series Landsat TM/ETM+imageries and historical data,relationships between urban land expansion and its influencing factors from 1989 to 2009 were analyzed by using an integrated approach of remote sensing(RS)and geographic information system(GIS)techniques.The results showed that built-up land increased from 151.16 km2in 1989 to 383.76 km 2in 2009. Approximately 64.25%of the newly emerging built-up land was converted from cropland(29.47%),forest and shrub (25.78%),water(3.73%),wetland(4.61%),and bare land(0.66%)during 1989 and 2009.With a remarkable decrease in cropland,the proportion of non-agricultural population increased by 23.6%.Moreover,rapid development of infrastructures,facilities,industrial parks,and urban and rural settlements along the Minjiang River resulted in the eastward and southward expansion of built-up land.Additionally,the growth pattern of built-up land in the NWDA is highly correlated with socio-economic factors,including the gross domestic product(GDP),GDP per capita,and structure of industry.As a result,the observed environmental degradation such as loss of cropland and wetland due to heavy pressure of rapid urbanization have greatly impaired the carrying capacity of city.Thus,in addition to scientific and rational policies towards minimizing the adverse effects of urbanization,coordination between the administrative agencies should be urgently strengthened to balance the conflicts between urban development and ecological conservation to make sure the sustainable land use.

Assessment of Ground Water Dynamics and Potential Zones in Urban Areas: A Case Study of Voi Town, Kenya

Water plays a role in sustaining all the biotic elements. Unfortunately, in the recent times with persistent climate change impacts, parts of the world are facing cases of inadequate water causing stress and increased vulnerability among the people. This is the case with urban areas across the globe as their populations keep increasing with little to no attention paid to urban planning that allows sustainable management of resources amidst rapid development. Urban areas are surrounded by high yielding aquifers that have better water services from groundwater. However, the urban sprawl phenomena have limited attempts in assessing ground water potential in urban areas contributing to urban water scarcity. Therefore, the study aims to look at the problem of urban water scarcity, by analyzing the levels and distribution of groundwater in Voi town using remote sensing and GIS techniques, in order to suggest suitable sites for underground water exploration in regard to the overall urban water supply. From the analysis, the results showed that the area majorly has low to potential zones of groundwater. High potential areas were very few and were mostly on the western side of the area. Very low potential zones were seen on the east and north side of the area.

Monitoring Surface Water Change in Northeast China in 1999–2020:Evidence from Satellite Observation and Refined Classification

As a typical region with high water demand for agricultural production,understanding the spatiotemporal surface water changes in Northeast China is critical for water resources management and sustainable development.However,the long-term variation characteristics of surface water of different water body types in Northeast China remain rarely explored.This study investigated how surface water bodies of different types(e.g.,lake,reservoir,river,coastal aquaculture,marsh wetland,ephemeral water) changed during1999–2020 in Northeast China based on various remote sensing-based datasets.The results showed that surface water in Northeast China grew dramatically in the past two decades,with an equivalent area increasing from 24 394 km^(2) in 1999 to 34 595 km^(2) in 2020.The surge of ephemeral water is the primary driver of surface water expansion,which could ascribe to shifted precipitation pattern.Marsh wetlands,rivers,and reservoirs experienced a similar trend,with an approximate 20% increase at the interdecadal scale.By contrast,coastal aquacultures and natural lakes remain relatively stable.This study is expected to provide a more comprehensive investigation of the surface water variability in Northeast China and has important practical significance for the scientific management of different types of surface water.

Water quality monitoring in a slightly-polluted inland water body through remote sensing-Case study of the Guanting Reservoir in Beijing,China

This study focused on the water quality of the Guanting Reservoir,a possible auxiliary drinking water source for Beijing.Through a remote sensing(RS)approach and using Landsat 5 Thematic Mapper(TM)data,water quality retrieval models were established and analyzed for eight common water quality variables,including algae content,turbidity,and concentrations of chemical oxygen demand,total nitrogen,ammonia nitrogen,nitrate nitrogen,total phosphorus,and dissolved phosphorus.The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation.With an appropriate method of sampling pixel digital numbers and multiple regression algorithms,retrieval of the algae content,turbidity,and nitrate nitrogen concentration was achieved within 10% mean relative error,concentrations of total nitrogen and dissolved phosphorus within 20%,and concentrations of ammonia nitrogen and total phosphorus within 30%.On the other hand,no effective retrieval method for chemical oxygen demand was found.These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring.The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.

基于RS、GIS的城市绿地生态效益评价与预测模型

以遥感(RS)信息作为主要的数据来源,结合其他实地监测和统计数据,采用GIS技术进行数据分析和处理,建立城市绿地生态效益评价与预测模型,为城市绿地规划、改善城市生态环境提供定量化的科学依据。

基于RS的水库水位面积曲线测定

现利用Erdas软件,以大汶河流域雪野水库近年的TM影像为基础资料,结合图像处理和遥感应用原理进行了水库库区水面体栅格影像的最小距离监督分类提取,提出了基于遥感技术的水库水域面积提取分析方法,结合水文统计观测数据,得到水库水位面积曲线。相比传统的水库面积测量方法,具有快速,精准,效率高的优势,大大简化了测量过程。

RS、GIS在内陆湖泊水质研究中的应用

:遥感 (RS)、地理信息系统 (GIS)技术的综合应用在许多研究领域广泛推广并日渐成熟 ,表现出广阔的发展前景。将 RS、GIS相结合 ,综合应用于内陆湖泊水质的监测和分析 ,充分体现了其快速、经济、高效的强大优势。本文首先回顾了一般监测方法的特点及局限性 ,主要讨论了 RS、GIS的特点及在内陆湖泊监测和分析中的优势所在。

基于CBERS数据的农区水体透明度遥感模型研究

以南京溧水县为研究区,以溧水县农区水体为研究对象,利用免费的CBERS的CCD数据和同步监测的农区水体透明度实测数据,结合灰色系统理论进行灰色关联度分析,选取关联度最大的波段组合(b3/b1)作为建模因子,建立农区水体透明度的遥感定量监测模型,探讨农区水体透明度与CBERS影像各波段的相关性。最后应用该模型监测2007年7月30日溧水县的农区水体,监测结果较客观反映了水体透明度的真实分布情况。结果表明:农区水体透明度与CBERS 1、3波段有最好的相关性,所建的农区水体透明度遥感定量监测模型为y=-15 529x3+53 244x2-60 600x+22 938,x=b3/b1(R2=0.92,F=15.26,P=0.01),模型的检验精度较高,已符合建模要求;利用CBERS数据进行农区水体透明度监测具有重要的现实意义和应用前景。

基于GIS和RS技术的土壤侵蚀快速调查研究

随着地理信息系统GIS技术、遥感RS技术的发展,在土壤侵蚀快速调查中得到了广泛的应用。本文采用三要素(即植被覆盖度、地形坡度和土地利用)进行土壤侵蚀的快速调查,其中对植被覆盖度分别采用了线性拟合法和神经网络法进行了计算和分析,神经网络法可以考虑到多个影响因素,因此成果比线性拟合法具有更好的精度。

基于RS&GIS的证据权重法在花山岩体铀矿成矿预测中的应用

以遥感为主要技术手段,对广西花山花岗岩岩体铀矿点的遥感地质特征进行研究,获取了大量与矿化有关的信息。经MapGIS平台分析地质单元、地质构造、地质复杂度、蚀变信息、热异常信息与成矿的关联度,挑选出10种与成矿有关的证据因子,建立了基于GIS的证据权重法找矿预测模型。运用证据权重模型对各成矿证据因子进行综合预测分析,计算出基于网格单元的各因子的权重值,通过各网格单元的信息量总和得出后验概率值,根据后验概率值的大小,对研究区进行铀矿找矿靶区的预测,圈定出4个级别的成矿远景区。

GIS与RS支持下的城市总体规划生态空间导向性控制——以重庆市长寿为例

城市生态空间导向性控制策略是城市总体规划的重要环节,是构建可持续发展城市的前提条件。以重庆市长寿为例,利用地理信息系统与遥感技术建立城市生态环境空间数据库,选取生态敏感性评价指标,构建城市空间生态敏感性评价模型,并在此基础上制定城市生态空间导向性控制策略。结果表明可以借助GIS和RS进行城市生态空间结构识别并以此为基础构建城市和谐生态空间控制方法。

径向基函数网络与GIS/RS融合的UGB预测

针对城市空间增长特点,探究城市扩展的规律,研究城市增长边界的计算和预测模型,这对于城市的发展规划具有重要的意义。然而,在国内外,关于城市增长边界方面的研究较少,首次提出利用人工神经网络、地理信息系统和遥感相结合的技术建立具有复杂几何形状的城市增长边界模型。通过数值实验结果表明,模型对城市未来增长边界的计算和预测准确度达80%～84%,结果表示直观、真实,能够为当前精明增长模式下的城市用地规划工作提供决策参考。

基于RS的黄三角经济区海岸带提取方法

在分析黄河三角洲及附近海域潮汐规律的基础上,提取了高潮线、海岸线和低潮线等海岸带的基本要素,海岸线和高潮线的提取采用简便易行的目视解译方法直接获得;对于较难提取的低潮线,引入了遥感水深理论,建立水深模型,结合当地潮汐、潮位资料和DEM数据进行了推算,最终完成黄河三角洲经济区海岸带的提取工作。结果表明:利用水深遥感模型反演得到的低潮线虽然有一定误差,但并不影响进一步研究,与传统方法相比具有快速、简捷的优点。

RS-based Analysis of the Correlation between Brightness Temperature and Vegetation Cover—A Case Study of Neijiang City,Sichuan Province of China

Landsat TM data(June 23,1988,May 6,2007) and Landsat ETM+data(May 10,2000) of Neijiang City,Sichuan Province was taken as the data source,brightness temperature of the study area was obtained by using TM/ETM+thermal infrared wave,and also normalized difference vegetation index(NDVI) was calculated.NDVI of the study area on June 23,1988,May 6,2007,and May 10,2000 was respectively obtained by using Band Math,the least square fitting was adopted to simulate the correlation between surface temperature and vegetation cover.Moreover,linear regression analysis of the correlation between vegetation cover and NDVI was carried out in Excel.The results showed that(a) most of the constructed area has a low NDVI value because there are large areas of hard surface such as buildings and roads,but less vegetation cover;(b) the quarters with better vegetation cover have higher NDVI values;the Tuojiang River has a negative NDVI value;rural areas have better vegetation cover and higher NDVI values.Brightness temperature and vegetation cover has distinct negative correlation,specifically,the higher the vegetation cover is,the lower the surface temperature is,and vice versa.

基于RS的城镇用地信息提取及格局发展研究

选取2000年与2015年Landsat ETM+/OLI遥感影像为数据源,以齐齐哈尔市为例,利用波段构建增强的指数型建筑用地指数(Enhanced Index-based Built-up Index,EIBI),提取该市2000年及2015年城镇建设用地数据,提取精度达到90%以上。选取年均扩展率、扩展强度指数、间隙度指数、平均分形维数和空间关联指数作为研究指标,剖析齐齐哈尔市城镇格局的时空演变特征,耦合自然与人为因素,揭示该市城镇化进程和特点,并对进一步加快城镇建设进行思考。结果表明:利用EIBI提取城镇用地信息过程客观、效率较高,人工修正后精度达到95%以上。齐齐哈尔市2000年城镇建设用地面积为147 186.69 hm^2,2015年为201 015.38 hm^2,年均扩展率为2.10%,扩展强度为9.10%。城镇外形结构变得相对复杂,城镇化发展具有较低水平的多元化分散分布特征,城镇扩张冷热点分布不均,空间联系程度低,未出现城区与乡镇的区域协调快速发展。齐齐哈尔市城镇化发展空间潜力较大,亟需合理解决阻碍城镇建设的障碍。

Analysis of Urban Land Use and Its Effects on Air Environment in Chengdu, Western China from 1992 to 2008

Large-scale development of urban land use has led to change of a variety of natural processes and ecological processes, resulting in complex eco-environmental consequences. The objective of this study was to analyze the urban land use and its impact on air environment effect in Chengdu, western China from 1992 to 2008 following the RS (Remote Sensing) and GIS technique. The environmental effects data of urban land use was extracted and analyzed by overlaying layers of urban land use and the density of nitrogen dioxide and total suspended particulate matter in sampling points data concerning to the air quality of the environment in Chengdu based on GIS spatial analysis method. The results show that the main feature of urban land use change was substantial reduction of cultivated land and construction land and forest land increased significantly within the study area from1992 to 2008. The temporal-spatial change was notable in study period time. Land use has a significant impact on urban air environment, the chroma change of nitrogen dioxide derived from forest land was obvious, the area occupied by different nitrogen dioxide chroma was the largest. The urban land use impact on the highest class chroma of total suspended particulate matter was notable and its area was the greatest. The results show also the spatial distribution of nitrogen dioxide chroma and total suspended particulate matter chroma in study area is reduced following from Qingbaijiang District-Xindu District-downtown to both sides. The spatial distribution of industry, mining and traffic land is basically the same chroma spatial distribution. Therefore, the results of this study provide a scientific basis for improvement air environment quality, the urban sustainable development and a scientific response for decisions from the municipal governments.

基于RS和GIS的南宁市绿地景观空间结构分析

以南宁市的绕城高速公路G7201以内的建成区的Landsat8影像为研究对象,在RS、Arcgis、ENVI以及Patch analyst技术支持下,运用景观格局生态学的理论和方法,对南宁市城市绿地景观格局结构进行分析。结果表明,绿地景观结构分布不合理,绿地斑块破碎化程度较高,南宁市中心城区绿地景观格局中农业用地比重最大,比重最小的廊道绿地板块多、面积小,破碎化程度高。建议南宁市在今后的城市绿地建设中,优化城市绿化格局,降低绿地破碎度,增强廊道绿地建设。通过带状的廊道绿地,使城市中的其他绿地类型连成一片,形成较好的生态走廊。

基于机器学习的寒区渠道冰情的遥感监测方法

寒区渠道冬季运行时常出现冰情,控制平封的封冻过程会大幅降低渠道输水能力,调控不当甚至可能产生冰塞、冰坝等灾害。国内外开展了大量渠道冰情研究,以期提升渠道冰期输水能力,但受限于观测资料的时空密度,数值模拟结果难以验证,调度决策缺少依据。遥感技术因其具有监测范围大、时效性高的特性,在渠道冰情监测中具有较大的应用潜力。为探索适用于寒区渠道冰情遥感监测的方法,该研究以南水北调中线京石段明渠段为研究区,基于Sentinel-2影像的11个波段反射率构建了完全特征、优选特征和组合特征3类特征空间数据集,作为支持向量机(support vector machine,SVM)、最大似然估计(maximum likelihood estimation,MLE)、随机森林(random forest,RF)分类算法输入,训练得到了9个地物分类器,用于渠道结冰范围识别,并采用北拒马闸前影像渠道结冰范围提取试验,对比不同分类算法和输入特征组合下的分类性能。结果表明:在渠道结冰范围识别中,近红外、可见光和短波红外是关键波段。在样本数量有限的条件下,SVM算法结冰范围识别精度最高,不同特征输入下制图精度(producer’s accuracy,PA)可达85.10%~87.91%,错分误差(commission error,CE)为10.84%~16.08%;RF算法在完全特征和优选特征输入下分类精度与SVM接近,PA为84.67%~86.61%,CE为13.76%~14.41%,但其在组合特征下分类结果严重偏离实际;MLE算法在3类特征下的分类精度均较低,不适宜作为渠道结冰范围识别算法。综合来看,SVM算法对特征空间敏感性较低,在不同的特征输入下均能实现渠道结冰范围的高精度提取;RF算法对特征空间敏感性较高,当输入特征发生变化时,结冰范围识别精度不稳定。最后以完全特征下的SVM算法为例,进行了分类器的时空泛化性验证,结果表明模型在不同时间、不同渠段下,制图精度不低于82.09%,错分误差不高于13.82%,分类模型精度均较好,能有效识别渠道结冰范围。该研究方法可为寒区输水工程冰情监测提供新思路,亦可为类似工作提供参考。