Glaciers in the Himalaya are often heavily covered with supraglacial debris,making them difficult to study with remotely-sensed imagery alone.Various methods such as band ratios can be used effectively to map clean-ic...Glaciers in the Himalaya are often heavily covered with supraglacial debris,making them difficult to study with remotely-sensed imagery alone.Various methods such as band ratios can be used effectively to map clean-ice glaciers;however,a thicker layer of debris often makes it impossible to distinguish between supraglacial debris and the surrounding terrain.Previously,a morphometric mapping approach employing an ASTER-derived digital elevation model has been used to map glaciers in the Khumbu Himal and the Tien Shan.This study on glaciers in the Greater Himalaya Range in Zanskar,southern Ladakh,aims (i) to use the morphometric approach to map large debris-covered glaciers;and (ii) to use Landsat and ASTER data and GPS and field measurements to document glacier change over the past four decades.Field work was carried out in the summers of 2008.For clean ice,band ratios from the ASTER dataset were used to distinguish glacial features.For debris-covered glaciers,topographic features such as slope were combined with thermal imagery and supervised classifiers to map glacial margins.The method is promising for large glaciers,although problems occurred in the distal and lateral parts and in the fore field of the glaciers.A multi-temporal analysis of glaciers in Zanskar showed that in general they have receded since at least the mid-to late-1970s.However,some few glaciers that advanced or oscillated - probably because of specific local environmental conditions - do exist.展开更多
Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static enviro...Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.展开更多
0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the tra...0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).展开更多
In this article, we review the current knowledge of the glacial recession and related glacial lake development in the Andes of South America. Since the mid-1980 s, hundreds of glacial lakes either expanded or formed, ...In this article, we review the current knowledge of the glacial recession and related glacial lake development in the Andes of South America. Since the mid-1980 s, hundreds of glacial lakes either expanded or formed, and predictions show that additional hundreds of lakes will form throughout the 21 st century. However, studies on glacial lakes in the Andes are still relatively rare. Many glacial lakes pose a potential hazard to local communities, but glacial lake outburst floods(GLOFs) are understudied. We provide an overview on hazards from glacial lakes such as GLOFs and water pollution, and their monitoring approaches. In real-time monitoring, the use of unmanned aerial systems(UASs) and early warning systems(EWSs) is still extremely rare in the Andes, but increasingly authorities plan to install mitigation systems to reduce glacial lake risk and protect local communities. In support, we propose an international remote sensing-based observation initiative following the model of, for example, the Global Land Ice Measurements from Space(GLIMS) one, with the headquarters in one of the Andean nations.展开更多
基金the generosity of The University of Montana and the German Research Foundation (DFGBU 949/15-1)a research fellowship from the Alexander von Humboldt Foundation awarded to Ulrich Kamp
文摘Glaciers in the Himalaya are often heavily covered with supraglacial debris,making them difficult to study with remotely-sensed imagery alone.Various methods such as band ratios can be used effectively to map clean-ice glaciers;however,a thicker layer of debris often makes it impossible to distinguish between supraglacial debris and the surrounding terrain.Previously,a morphometric mapping approach employing an ASTER-derived digital elevation model has been used to map glaciers in the Khumbu Himal and the Tien Shan.This study on glaciers in the Greater Himalaya Range in Zanskar,southern Ladakh,aims (i) to use the morphometric approach to map large debris-covered glaciers;and (ii) to use Landsat and ASTER data and GPS and field measurements to document glacier change over the past four decades.Field work was carried out in the summers of 2008.For clean ice,band ratios from the ASTER dataset were used to distinguish glacial features.For debris-covered glaciers,topographic features such as slope were combined with thermal imagery and supervised classifiers to map glacial margins.The method is promising for large glaciers,although problems occurred in the distal and lateral parts and in the fore field of the glaciers.A multi-temporal analysis of glaciers in Zanskar showed that in general they have receded since at least the mid-to late-1970s.However,some few glaciers that advanced or oscillated - probably because of specific local environmental conditions - do exist.
基金the National Natural Science Foundation of China(Grant No.42271078)Key Research and Development Program of Shaanxi(2024SF-YBXM-669)。
文摘Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.
基金funded by the National Natural Science Foundation of China(No.42271078)the Key Research and Development Program of Shaanxi(No.2024SF-YBXM669)。
文摘0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).
文摘In this article, we review the current knowledge of the glacial recession and related glacial lake development in the Andes of South America. Since the mid-1980 s, hundreds of glacial lakes either expanded or formed, and predictions show that additional hundreds of lakes will form throughout the 21 st century. However, studies on glacial lakes in the Andes are still relatively rare. Many glacial lakes pose a potential hazard to local communities, but glacial lake outburst floods(GLOFs) are understudied. We provide an overview on hazards from glacial lakes such as GLOFs and water pollution, and their monitoring approaches. In real-time monitoring, the use of unmanned aerial systems(UASs) and early warning systems(EWSs) is still extremely rare in the Andes, but increasingly authorities plan to install mitigation systems to reduce glacial lake risk and protect local communities. In support, we propose an international remote sensing-based observation initiative following the model of, for example, the Global Land Ice Measurements from Space(GLIMS) one, with the headquarters in one of the Andean nations.
