Long-term coastal erosion assessment along the coast of Karnataka,west coast of India     

K.Sowmya  M.Dhivya Sri  Aparna S.Bhaskar  K.S.Jayappa 《国际泥沙研究》2019,34(4):335-344

Coastal areas are always under frequent threat from various natural processes and man-induced activities. Coastal erosion is recognized as the permanent loss of land along the shoreline resulting in the transformation of the coast. The current study focuses on long-term coastal erosion analysis of the entire Karnataka coast using Remote Sensing, Geographical Information System (GIS), Linear Regression Rate (LRR), and End Point Rate (EPR) techniques. Analysis of 26 (1990 to 2016) years of erosion using Landsat images by the use of the Digital Shoreline Analysis System (DSAS) tool has been done. The results show a high erosion rate at Ullal during this period (LRR -1.3m/yr) and accretion at Devbagh (LRR 3.2 m/yr). The southern Karnataka coast faces severe erosion especially at Ullal, where the settlement is high. At Thanirbhavi, Mukka, Kota, and Om Beaches erosion also is noticed. Both anthropogenic activities like ports, seawalls, breakwaters, etc. and natural processes like long shore drift, seasonal variation, etc. are factors affecting the shoreline change along the Karnataka coast.  相似文献   

1974-2017年洪湖湿地自然保护区景观格局演变及驱动力分析   总被引：6，自引：2，他引：4  

张莹莹  蔡晓斌  杨超  宋辛辛  李仁东  厉恩华  王学雷 《湖泊科学》2019,31(1):171-182

利用Landsat系列遥感影像数据（1974、1979、1984、1990、1996、2001、2006、2009、2014和2017年）解译得到的土地利用/土地覆盖变化（LUCC）结合研究区44年的气温、降水量、水位等气象水文数据,构建LUCC经验统计模型和计算景观格局指数,探讨1974-2017年洪湖国家级自然保护区景观格局变化的主要驱动因素.研究结果表明：土地利用强度指数由1974年的207增加到2017年的249.36,人类开发利用湖滨带的程度增强,到2017年约有30%的自然湿地转化为坑塘、农田和滩地及建设用地.不同地表覆盖类型的景观格局指数均发生了较大变化,2000年以后湖滨带逐渐形成了以养殖为主的低矮围景观.总体上景观趋于破碎化、连通性降低、稳定性变弱.洪湖湿地自然保护区土地利用强度指数与景观格局综合指数呈较显著的正相关,两者的相关系数为0.84,土地利用强度增加则景观更加破碎、斑块之间的连接程度减弱、区域的景观聚集度下降和景观异质性增加.总体而言,洪湖湿地自然保护区受人为干扰影响明显,开展封湖育草自然恢复与建立植被恢复示范区相结合,构建自湖滨至湖心的梯度变化完整的湿生植被-挺水植被-漂浮植被-浮叶植被-沉水植被的水生植物群落,退耕还草、退垸还湖、修复湖滨带植被,大幅度提高洪湖的自净能力,增加其水生植物多样性,实现湿地的有效修复,改善其结构和功能,维系洪湖湿地生态系统的平衡.  相似文献   

Impacts of Holocene and modern sea-level changes on estuarine mangroves from northeastern Brazil     

Marcelo C.L. Cohen  Beatriz L. Figueiredo  Nedra N. Oliveira  Neuza A. Fontes  Marlon Carlos França  Luiz C.R. Pessenda  Adriana V. de Souza  Kita Macario  Paulo C.F. Giannini  José A. Bendassolli  Paula Lima 《地球表面变化过程与地形》2020,45(2):375-392

Projections of the impacts of modern Relative Sea Level (RSL) rise on estuarine mangroves should be supported by coastal topographic data and records of mangrove dynamics under past RSL change. This work identified inland and seaward mangrove migrations along the Jucuruçu River (Bahia, Northeastern Brazil), during the Holocene based on sedimentary features, palynological and geochemical (δ¹³C, δ¹⁵N, C/N) data integrated with digital elevation models. During the Middle Holocene, in response to RSL rise, the estuary saw mangrove forest establish up to ~37 km inland. RSL stood between -1.4 (+0.36/-2.2 m) and +1 (2.19/0.2 m) around 7400 cal yr BP, and rose to a highest position of +3.25 (4.22/2.45 m) reached around 5350 cal yr BP. That marine incursion caused the inland replacement of freshwater vegetation by mangroves on tidal flats. Since then, the estuary experienced RSL fall, reducing inland tidal water salinity towards the Late Holocene, making that the mangroves were replaced by freshwater floodplain vegetation. Today, in the seaward part of the estuary near its mouth, mangroves occupy an area of ~10 km² along tidal channels. Considering a RSL rise of 98 cm up to the end of the 21^st century, at a rate significantly higher than that of Middle Holocene RSL rise (1.5 mm/yr) and fall (0.6 mm/yr), the current mangrove substrates are expected to drown and/or eroded near the coast, while new mangroves may establish inland, at topographically higher tidal flats in nowadays freshwater-tidal zones. Mangrove area could expand over 13 km² of coastal and flood plain. Following the same interaction between RSL/climate changes and Holocene mangrove dynamics, such upstream mangrove migration may be attenuated or intensified by changes in fluvial discharge. © 2019 John Wiley & Sons, Ltd.  相似文献   

基于多源遥感数据的北京市1973-2005年间城市建成区的动态监测与驱动力分析   总被引：42，自引：0，他引：42  

牟风云  张增祥  迟耀斌  刘斌  周全斌  王长有  谭文彬 《遥感学报》2007,11(2):257-268

城市地域空间扩展情况是衡量城市化水平的重要测度指标。利用陆地卫星MSS影像、TM（或ETM＋）影像、灾害监测星座数据和“北京一号”小卫星数据,对1973—2005年北京市建成区的扩展过程、面积变化和土地利用影响进行了监测分析。结果表明：32年间,北京市建成区面积净增加超过1000km2,2005年达到1209.97km2,相当于1973年的6.58倍,年均扩展32.07km2。北京市建成区的扩展基本上呈现出以旧城区为中心向四周扩展的方式,并未在某一方向表现出特别明显的变化,但在不同时期内的扩展速度差异非常明显。北京市建成区的扩展面积中,54.34%来自于农村居民点和独立工矿用地及其他建设用地,43.57%来自于水田、旱地等耕地。人口增长对北京市建成区的扩展有显著的刺激作用;经济增长是城市变化的主要动力之一;交通的发展促进了城市用地的扩展,是城市扩展的牵引力,对城市空间扩展具有指向性作用;而政策与制度因素则在很大程度上决定了北京市发展和扩张的宏观格局。  相似文献   

利用卫星遥感影像对山东省1∶1万基础测绘数据进行更新的方法探讨     

赵云昌  丁莹莹  梁坤 《山东国土资源》2009,25(10):48-49,52

利用遥感应用软件,对SPOT5遥感影像进行纠正,在Photoshop和Geoway等软件支持下,叠合卫星遥感影像与航空影像,确定变化区域,进行遥感影像与矢量数据同名点的配准,矢栅叠加,再结合外业调绘,进行数据库更新。  相似文献   

北京1号小卫星多光谱影像全国镶嵌技术与制图研究   总被引：1，自引：0，他引：1       下载免费PDF全文

汪爱华 《遥感学报》2009,13(1)

北京1号小卫星在轨运行一年多成功接收了覆盖中国各个行政区域的多光谱影像数据,为全国数字镶嵌图的研究提供了丰富的数据资料.针对北京1号小卫星特点进行关键技术和方法研究,形成了北京1号小卫星多光谱影像全国范围数据获取任务测控优化模式,解决了北京1号小卫星多光谱数据预处理中去条带、波段自动配准、MTF复原处理等关键技术,系统地、全面地阐述了全国镶嵌图制作的技术流程和方法.  相似文献   

Remote sensing classification approach to large-scale crop cultivation identification: A case study of the Aral Sea Basin     

Zhuojian Wen  Desheng Jiang  Ye Jing  Guilin Liu 《Transactions in GIS》2023,27(8):2278-2296

Since the collapse of the Soviet Union, the crop cultivation structure in the Aral Sea Basin has changed dramatically, and these changes are worth studying. However, historical crop remote sensing mapping at the watershed scale remains challenging, especially crop misclassification at the cropland edge due to mixed pixels. Therefore, we proposed a field segmentation approach to constrain field edges based on time-series Sentinel-2 remote sensing images and the Google Earth Engine platform and then employed the random forest algorithm to perform crop classification based on time series Landsat/Sentinel-2 images and crop phenology information to produce historical crop maps in the Aral Sea Basin from the 1990s onward. The results showed that the intersection over union between the extracted field edges and in situ-measured field size data was 0.65. The overall accuracy of crop mapping was 95.2% in 2019. Then, we extended our method to historical mapping over the 1991–2015 period with accuracies ranging from 82.8% to 91.3%. Moreover, our method applied to historical mapping works well in terms of accuracy and policy matching. These findings indicate that our method can accurately distinguish cropland edges to reduce classification errors due to mixed pixels. This method is promising for solving the cropland edge problem for historical crop mapping in the Aral Sea Basin and can potentially provide a reference for historical crop classification in other watersheds of the world.  相似文献   

基于百度AI卷积神经网络的茶树结霜智能识别北大核心          下载免费PDF全文

朱兰娟  胡德云  华行祥  李时睿  杨欣洁  张旭晖 《气象科学》2023,43(2):245-253

基于采集的近20000张茶园图像,分别筛选出1000张茶园结霜和1000张未结霜图像作为训练样本,利用百度AI开放平台的EasyDL经典版图像识别功能,应用卷积神经网络算法,建立茶园结霜识别模型,进行茶树结霜图像智能判别。茶树结霜智能识别模型的准确率、F1评分、精确率、召回率分别为99.2%、99.2%、99.3%、99.1%。模型检验结果为:样本地20张结霜图像的平均识别置信度为95.51%,20张非结霜图像的平均识别置信度为99.99%;非样本地(江南茶区)80张结霜图像的平均识别置信度为97.53%,80张非结霜图像的平均识别置信度为95.11%。  相似文献   

综合方法在1∶5万区调工作中的应用     

高德臻 《地质与勘探》1998,(6)

介绍了在１∶５万区域地质调查中，利用地球物理资料编制立体构造图、利用ＩＣＰＳ—Ⅲ型微机图形图像处理系统对遥感ＴＭ图像进行有效处理、建立多元信息库等方面的研究成果  相似文献   

一种基于Choquet模糊积分小波系数选择的遥感图像融合方法          下载免费PDF全文

凌静  徐立中  石爱业  黄凤辰  汤敏 《遥感学报》2009,13(2):263-268

为较好地保留多光谱、高分辨率遥感影像融合时的光谱信息和高分辨率信息,在小波变换基础上提出了一种基于模糊积分的融合算法,其基本思想是在IHS空间,对强度分量Ⅰ及高分辨率图像进行小波分解后,保留Ⅰ分量的低频系数,对于高频细节特征,将局部窗口内的方差、平均梯度和能量当作单因素指标,应用Choquet模糊积分综合各单因素指标得到一个综合指标,并据此来选取小波系数.实验结果表明,该算法在光谱质量改善方面明显优于IHS以及一些经典的小波变换遥感图像融合算法,是一种有效的遥感图像融合算法.  相似文献