Ecological environment quality evaluation of the Sahel region in Africa based on remote sensing ecological index

Long-term monitoring of the ecological environment changes is helpful for the protection of the ecological environment.Based on the ecological environment of the Sahel region in Africa,we established a remote sensing ecological index(RSEI)model for this region by combining dryness,moisture,greenness,and desertification indicators.Using the Moderate-resolution Imaging Spectroradiometer(MODIS)data in Google Earth Engine(GEE)platform,this study analyzed the ecological environment quality of the Sahel region during the period of 2001-2020.We used liner regression and fluctuation analysis methods to study the trend and fluctuation of RSEI,and utilized the stepwise regression approach to analyze the contribution of each indicator to the RSEI.Further,the correlation analysis was used to analyze the correlation between RSEI and precipitation,and Hurst index was applied to evaluate the change trend of RSEI in the future.The results show that RSEI of the Sahel region exhibited spatial heterogeneity.Specifically,it exhibited a decrease in gradient from south to north of the Sahel region.Moreover,RSEI in parts of the Sahel region presented non-zonal features.Different land-cover types demonstrated different RSEI values and changing trends.We found that RSEI and precipitation were positively correlated,suggesting that precipitation is the controlling factor of RSEI.The areas where RSEI values presented an increasing trend were slightly less than the areas where RSEI values presented a decreasing trend.In the Sahel region,the areas with the ecological environment characterized by continuous deterioration and continuous improvement accounted for 44.02%and 28.29%of the total study area,respectively,and the areas in which the ecological environment was changing from improvement to deterioration and from deterioration to improvement accounted for 12.42%and 15.26%of the whole area,respectively.In the face of the current ecological environment and future change trends of RSEI in the Sahel region,the research results provide a reference for the construction of the"Green Great Wall"(GGW)ecological environment project in Africa.

Evaluation of Natural Ecological Environment in Guangzhou City Based on Remote Sensing Technology and Comprehensive Index Method

Based on the ETM remote sensing images of Guangzhou City in 2014, the spatial distribution results o f three environmental factors including vegetation coverage(NDVI), soil index(vegetation index of bare soil) and sl ope were obtained. By using comprehensive index method, the normalized environmental factors were weighted and superimposed, and the fi nal evaluation results of ecological environment in Guangzhou City were obtained. The results showed that overall situation of natural ecological environment in Guangzhou was not optimistic, that is, the area of land with bad, moderate, good and superior environment accounted for 59.70%, 35.79%, 4.50% and around 0.01% of total area of land in Guangzhou City respectively. Ecological environment was generally poor in the central urban districts in the south of Guangzhou City, while it was relatively better in the north and northeast. Attaching importance to the constr uction of greenbelts and greenways is an effective way to improve regional environmental quality and natural ecological e nvironment level.

Eco-Environment Evaluation of Grassland Based on Remote Sensing Ecological Index: A Case in Hulunbuir Area, China

This research is based on Landsat5 TM, Landsat8 OLI/TIRS remote sensing data using RSEI model to analyze and monitor the ecological environment and its temporal and spatial changes in the forest-grass transition zone in Northeast China from 2004 to 2019. The change characteristics of the ecological environment of different types of land cover types are monitored by RSEI method, and the response of different land cover types to natural factors such as precipitation and temperature is analyzed at the same time. The distribution of RSEI in the study area presents the characteristics of high in the east and low in the west. The eastern mountainous area is densely covered with woodland, which is the area with the best ecological environment quality in the study area. The grassland in the western plain and the saline-alkali land around the river are the areas with poor ecological environment in the study area. Climate, precipitation, topography and other natural elements work together to form the quality of the ecological environment in the study area roughly bounded by 120?E. In years with poor natural conditions, this dividing line will have a clear eastward shifting trend, especially in the northern part of the study area. The spatial distribution of RSEI in the study area has a high degree of spatial autocorrelation, and Global Moran’s I has been above 0.8 over the years. In terms of temporal changes in ecological conditions, the ecological environment in the study area was basically stable from 2004 to 2008, with a slight deterioration;it improved significantly from 2008 to 2011;however, it deteriorated significantly from 2011 to 2019. According to the results of partial correlation analysis, the ecological environment of the former is highly correlated with natural elements such as climate and precipitation, while the latter is mainly affected by human factors.

Analysis of Ecological Environment Changes in Linze from 2000 to 2017 Based on Remote Sensing Images

With the support of RS and GIS technology,the ecological environment of Linze was evaluated and the changes of ecological environment were analyzed from the spatial scope of ecosystem with the remote sensing images in 2000 and 2017 as the information source.The results showed that the areas with excellent,relatively good and relatively poor ecological environment in Linze showed a decreasing trend from 2000 to 2017,which decreased by 262.50,7,156.25 and 12,256.30 hm^2,respectively.From the landscape patch pattern,the patch density in areas with relatively good ecological environment increased the fastest from 2000 to 2017,which was 13.05 pieces/hm^2.The largest plaque index in areas with relatively good ecological environment decreased by 1.314%,and the dominance of large plaque in the region decreased.The assessment results of ecological environment based on remote sensing demonstrated that the ecological environment in Linze was generally healthy from 2000 to 2017,and the deterioration was improved.Among them,the area transformed from relatively poor ecological environment to other types was the largest,which was 17,512.92 hm^2,and the proportion of the area transformed into general ecological environment was the highest,accounting for 80.7%of the transformed area of the region.

Assessment on eco-environmental quality of the Yellow River Basin by considering desertification index

Desertification has had a significant impact on the ecological environment of the Yellow River Basin(YRB)in China.However,previous studies on the evaluation of the ecological environment quality(EEQ)in the YRB have paid limited attention to the indicator of desertification.It is of great significance to incorporate the desertification index into the spatiotemporal assessment of the EEQ in the YRB in order to protect the ecological environment in the region.In this study,based on multi-source remote sensing data from 91 cities in the YRB,this article proposes a desertification remote sensing ecological index(DRSEI)model,which builds upon the traditional Remote Sensing Ecological Index(RSEI)model,to analyze the spatiotemporal changes in the EEQ in the YRB from 2001 to 2021.Furthermore,using the geographic detector(GD),and geographically and temporally weighted regression(GTWR)model,the study assesses the impact of human and natural factors on the EEQ in the YRB.The research findings indicate that:(1)Compared to the traditional RSEI,the improved DRSEI shows a decreasing trend in the evaluation results of the EEQ.Among the 24 cities,the change in DRSEI exceeds 0.05 compared to RSEI,accounting for 26.37%of the YRB.The remaining 67 cities have changes within a range of less than 0.05,accounting for 73.63%of the YRB.(2)The results of the GD for individual and interactive effects reveal that rainfall and elevation have significant individual and interactive effects on the EEQ.Furthermore,after the interaction with natural factors,the explanatory power of human factors gradually increases over time.The spatial heterogeneity results of GTWR demonstrate that rainfall has a strong direct positive impact on the EEQ,accounting for 98.90%of the influence,while temperature exhibits a more pronounced direct inhibitory effect,accounting for 76.92%of the influence.Human activities have a strong negative impact on the EEQ and a weak positive impact.

Integrated Evaluation of Ecological Security at Different Scales Using Remote Sensing: A Case Study of Zhongxian County, the Three Gorges Area, China

Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response （DPSER） model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed： 1） scale conversion of ecological security regime results from plxel to small watershed; and 2） scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.

Integrated Evaluation Model for Eco-Environmental Quality in Mountainous Region Based on Remote Sensing and GIS

Based on Remote Sensing （RS）, Geographic Information System （GIS）, and combining Principal Component Analysis, this paper designed a numerical integrated evaluation model for mountain eco-environment on the base of grid scale. Using this model, we evaluated the mountain eco-environmental quality in a case study area-the upper reaches of Minjiang River, and achieved a good result, which accorded well with the real condition. The study indicates that, the integrated evaluation model is suitable for multi-layer spatial factor computation, effectively lowing man＇s subjective influence in the evaluation process; treating the whole river basin as a system, the model shows full respect to the circulation of material and energy, synthetically embodies the determining impact of such natural condition as water-heat and landform, as well as human interference in natural eco-system; the evaluation result not only clearly presents mountainous vertical distribution features of input factors, but also provides a scientific and reliable thought for quantitatively evaluating mountain eco-environment.

Environmental Monitoring in Northern Aksu, China Based on Remote Sensing Ecological Index Model

In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of its social economy and ecological environment protection. This paper selects the Landsat series remote sensing images of the northern Aksu region in 2013, 2016, and 2019, and uses the tools such as ENVI5.3 and ArcGIS 10.8.1 to process the image data accordingly. The principal component analysis method is used to calculate the Remote Sensing Ecological Index (RSEI) of the northern Aksu region. The data show that: 1) The ecological environment quality index in the northern Aksu region in 2013, 2016, and 2019 was 0.706087, 0.25243 and 0.362991 respectively;2) The areas where the ecological environment quality declined significantly in the northern Aksu region were the human settlements and the Gobi, fan-shaped land and other special terrain areas;3) The humidity index and the heat index are the two factors that have the greatest impact on the ecological environment quality in the northern Aksu area. The data as a whole show that the ecological environment in the northern part of the Aksu region has deteriorated seriously, and the severely deteriorated area is close to the human living area.

Evaluation of the International Vehicle Emission (IVE) model with on-road remote sensing measurements

Intemational Vehicle Emissions （IVE） model funded by U.S. Environmental Protection Agency （USEPA） is designed to estimate emissions from motor vehicles in developing countries. In this study, the IVE model was evaluated by utilizing a dataset available from the remote sensing measurements on a large number of vehicles at five different sites in Hangzhou, China, in 2004 and 2005. Average fuel-based emission factors derived from the remote sensing measurements were compared with corresponding emission factors derived from IVE calculations for urban, hot stabilized condition. The results show a good agreement between the two methods for gasoline passenger cars＇ HC emission for all 1VE subsectors and technology classes. In the case of CO emissions, the modeled results were reasonably good, although systematically underestimate the emissions by almost 12%-50% for different technology classes. However, the model totally overestimated NOx emissions. The IVE NOx emission factors were 1.5-3.5 times of the remote sensing measured ones. The IVE model was also evaluated for light duty gasoline truck, heavy duty gasoline vehicles and motor cycles. A notable result was observed that the decrease in emissions from technology class State II to State I were overestimated by the IVE model compared to remote sensing measurements for all the three pollutants. Finally, in order to improve emission estimation, the adjusted base emission factors from local studies are strongly recommended to be used in the IVE model.

Space-Time Evolution and Problems of Ecological Environment of Junggar Basin

Geological conditions of Junggar Basin are analyzed in this study,it is located in the northwest arid areas of China with a vulnerable supergene eco-environment.Based on the relationship between underground water and ecological environment,natural geological conditions are combined to classify ecosystem types in the study area,space-time evolution of its eco-environment in three periods is discussed:1990,2000 and 2009;development and utilization of water resources in Junggar Basin as well as its eco-environment evolution laws are taken to analyze problems brought by eco-environment changes,focusing on the following points:A.decreasing area of permanent glacier in mountainous ecosystem,increasing volume of river runoff,reducing capacity of mountainous ecosystem in conserving water resources;B.decreasing underground water,overflowing belt shifting northwards;C.shrinking lake area;D.degrading natural vegetation;E.expanding area of cultivated land and construction land;F.more cultivated land influenced by salinization,showing an increasing trend between 1990 and 2000,maintaining stable between 2000 and 2009,which implies that traditional agricultural irrigation method has brought significant influence on the utilization of water resources,and resulted in the shifting area of salinization.

Application of aerial remote sensing in the study on vegetation in Guangzhou,China

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Geological environment in the South China Sea

The South China Sea(SCS),situated in southern China,at the junction of the Pacific Plate,the Eurasian Plate,and the Indian Ocean Plate,is a northeast-southwest trending semi-enclosed sea.It spans an area of approximately 3.5 million square kilometers and has an average water depth of about 1200 m,its deepest point reaching 5559 m.In 2021,a scientific expedition(called as U1 voyage)in the South China Sea was organized by the Innovation Research Team of Guangdong Special Key Program from March to April,this marks the first comprehensive scientific research voyage to the southern Uboundary corridor.Consisting of a total of 30 papers,this special issue is to share a portion of the research findings from this scientific expedition U1 voyage,covering six aspects:1)characteristics of the marine ecosystem in the SCS and its response to marine dynamic processes;2)multi-scale marine dynamic processes,sea-air interactions,and forecasting techniques in the SCS;3)geomorphology and geological structure;4)sedimentary processes and resource potential in the SCS;5)geostrategy,rights and interests maintenance and strategic countermeasures in the SCS;6)marine scientific instruments.By integrating the scientific research with the study of history,jurisprudence and international strategies,this issue presents new insights into the formation history and scope evolution of the SCS,and it also seeks to establish a new scientific framework based on the marine governance and development of the SCS.

The impact of Dunhuang railway construction on land desertification

The area that the railway will cross is a region with the main physiognomies of desert and Gobi with a most fragile ecological environment. It is also a region that is highly susceptible to man-made disturbance. The construction of railway will intensify soil erosion along the railway line to a certain degree. The map of soil erosion conditions in the section from Liugou to Dunhuang City in the range of 10 km each side along the line was compiled by using the techniques of remote sensing and geographic information system （GIS）. Based on analysis of the status of desertification and the influence of the railway construction projects, the changes of the types, intensities and the total amount of the soil erosion caused by the construction were predicted.

快速城镇化地区生态环境质量时空格局演变及对土地利用变化响应——以廊坊市北三县为例

对生态环境质量时空格局及其对土地利用变化的响应进行研究可为区域制定生态保护修复政策提供参考。通过构建遥感生态指数,对廊坊市北三县2000-2020年生态环境质量分布格局分析评价,利用地理加权回归模型探索生态环境质量变化对土地利用变化的响应。结果表明,北三县2000-2020年生态环境质量等级以“良”和“一般”为主,整体呈下降趋势,等级“较差”面积呈快速增长趋势。建设用地变化、土地利用强度变化和生态环境质量变化呈负相关关系,回归系数在空间上呈现较大的异质性;生态用地变化与生态环境质量变化呈正相关关系,回归系数在空间上异质性不强。城镇快速扩张的区域生态环境质量变化对建设用地变化和土地利用强度变化响应最显著。大量耕地向建设用地转变是区域生态环境变化的最主要影响因素,在国土空间规划中应划定城市边界,严格控制建设用地规模,提高集约节约利用水平,确保区域可持续发展。

遥感技术在矿区生态环境中的应用与发展

矿区生态环境的科学有效监测是矿区生态环境保护与治理的前提,对于促进生态文明建设具有重要意义。特别是近些年来在矿山环境检测、资源调查、环境规划与设计、安全监测等方面的应用与发展越来越普遍,对这方面的需求量也越来越大。卫星遥感技术以其监测范围广阔、时效性强、数据丰富、手段多样等特点,为矿区生态监测提供一种快速、动态、全面的技术手段。特别是遥感技术在算法、算力等方面的迅速发展极大地促进国内外矿区生态环境遥感监测研究的发展和进步,遥感技术在矿山生态环境中的应用有着广泛的意义和重要价值,是当前矿山环境保护和生态建设中不可或缺的一部分。

基于新遥感生态指数环境质量动态监测——以阜新市为例

气候灾害易影响生态环境,传统的遥感生态指数(RSEI)缺乏气候因素影响生态质量的研究,本研究引入气象因子并优化了生态因子的选择,更加综合全面评价区域内的生态环境质量。使用主成分分析法构建新遥感生态指数(NRSEI),对各因子及多因子交互分析。结果表明,NRSEI较RSEI各因子在第1主成分贡献率均值提升12.53%,并且NRSEI与各因子相关性为高度相关,3 a均值为0.853。分析了2013-2020年阜新市生态环境的变化特点和原因,并利用NRSEI对研究区域的生态环境质量进行动态监测和评估,总体来看,2013-2020年阜新市生态环境状况变好,对于阜新市与NRSEI相关性最高的单个因子是湿度因子,因此阜新市相关部门应注重对河流、湖泊和湿地的保护,减少建筑开发,以改善城市的环境质量。

北方农牧交错区生态环境质量动态评价及影响因素分析——以河北坝上地区为例

[目的]农牧交错区是我国典型的生态脆弱区,精准评估农牧交错区生态环境质量与影响因素对地区的生态环境保护及治理有重要作用,可以为区域生态文明建设与实现可持续发展提供科学参考。[方法]本文基于Google earth engine(GEE)平台,利用2000-2020年Landsat遥感影像、土地利用数据、植被净初级生产力数据,根据河北坝上地区的生态特点,构建新型遥感生态指数(new Remote Sensing Ecological Index,nRSEI),评估了河北坝上地区2000—2020年的生态环境质量动态变化特征,并引入地理探测器分析了影响生态环境质量变化的自然因素和社会经济因素。[结果](1)2000—2020年河北坝上地区nRSEI均值经历了“上升—下降—上升”的过程,总体表现为增加。研究区东侧生态环境质量较高,西部区域的生态环境质量略低;(2)2000—2020年期间河北坝上地区生态环境质量变化中改善的面积占比较高,占研究区总面积的76.16%,生态环境质量改善主要发生在研究区西部;恶化的面积占比为8.20%,生态环境质量下降主要发生在研究区东部;(3)2000—2020年期间河北坝上地区生态环境质量空间分布呈现出显著的空间自相关性,局部聚集以“高-高”和“低-低”为主:(4)2000—2020年,单因子中对生态环境质量影响较大的为自然因素中的温度、降水量和坡度以及社会经济因素中距一级、三级道路距离、距县政府距离;2000年和2010年与距一级、三级道路距离、距县政府距离交互的组合交互作用值较高;2005年、2015年和2020年则是与降水量交互的组合交互作用值较高。[结论]河北坝上地区的生态环境质量虽近年有所好转,但其仍处在生态脆弱地区,应重视其生态环境的保护及治理,减少气候变化和人类活动对生态环境造成的破坏。

宜昌地基遥感垂直观测系统探测精度分析研究

宜昌地基遥感垂直观测系统能够实时监测本区域上空云、雾、弱降水、风速、风向、温度、相对湿度、液态含水量垂直廓线、气溶胶浓度等探测要素,增强突发性、灾害性天气监测能力.该文针对宜昌地基遥感垂直观测系统探测数据的准确性评估问题,提出了一种观测要素评估方法.方法使用了同址探空站的观测资料作为参考标准,通过对比时空匹配的垂直探测数据,分析宜昌垂直观测系统各类探测数据的准确性.通过该系统的垂直廓线产品联合观测2024年2月宜昌雨雪冰冻灾害天气过程,进行多条垂直廓线融合应用研究.定量分析结果表明:宜昌地基遥感垂直观测系统的数据质量全部满足评估指标要求,探测数据与探空资料相关性总体较好,可为气象监测提供精密的观测数据.

松辽流域生态环境时空动态评价及驱动因素分析

目前,我国高度重视以流域为基础的生态文明建设。及时有效的评估流域生态环境质量时空变化并分析其驱动因素对于制定流域协同性保护以及以流域为基础的生态文明建设十分重要。本文基于以数据为关键要素的,依托于遥感产品得到的绿度指数、湿度指数、干度指数、热度指数四项指标运用主成分分析方法建立松辽流域生态环境评估模型,并探索生态环境质量变化情况及其原因。结果表明:①松辽流域的生态环境质量整体优良,呈“东北优,西南差”的空间分布。②2000-2020年,松辽流域生态质量总体呈变好局势。第一个十年生态质量得到巨大改善,第二个十年处于生态保护维护阶段。③从空间分布上看,生态评级较差及以下等级面积明显收缩,优良等级面积显著向外扩张。④人类的社会经济生产活动对于生态环境的质量评估有至关重要的作用,如何平衡社会经济生产与生态环境保护之间的关系是帮助生态环境恢复的关键。

基于遥感生态指数改进模型的沱江流域生态环境质量时空变化及驱动力研究

[目的]沱江流域面临严重的水土流失、水环境污染和土壤侵蚀等生态环境问题,开展流域生态环境质量评价对推动长江上游生态环境保护和流域社会经济高质量可持续发展具有重要意义。[方法]基于谷歌地球引擎平台,选取2000-2020年的Landsat遥感影像,以绿度、湿度、热度、干度、生物丰度指数构建生态环境质量评价模型,采用变异系数、一元线性回归和空间自相关分析方法对流域内生态环境质量的时空演变格局进行分析,并运用最优参数地理探测器模型(optimal parameter geographic detector model,OPGD)对其驱动力进行探测。[结果](1)2000-2020年,沱江流域生态环境质量多年平均值为0.66,等级以良为主,占比为63.01%。成都周边区县、内江、自贡、泸州等城镇地区生态环境质量较差,呈现南北低中间高的空间分布格局。(2)沱江流域生态环境质量总体呈下降趋势,生态环境质量变差的趋势显著,轻微退化和显著退化面积占比分别为19.75%和5.88%。人口密度大,社会经济发展水平高的城镇化地区,生态环境质量以较高波动为主,占比为18.15%。(3)2000-2020年沱江流域全局自相关莫兰指数范围为0.769~0.870,主要分布在第1象限和第3象限,局部自相关的高-高集聚区和低-低集聚区范围随时间呈显著变化,景观斑块破碎化明显。(4)OPGD结果表明,土地利用类型、坡度、高程、夜间灯光为流域生态环境质量变化的主要驱动因子,人口密度、气温和GDP为次要驱动因子,降水量和坡向因子影响较小。土地利用类型与其他因子交互作用增强对流域内生态环境质量变化的影响。[结论]改进的遥感生态指数模型对开展区域生态环境质量评价提供新方法,研究结果为生态环境保护提供参考。