河流的形成及演变与区域环境和人类活动密切相关。红水河位于石羊河流域中游,是研究中国西北地区环境变化和古文化演变的重要地区。本文基于从红水河沿岸连续采集的5个剖面,结合历史地理资料和TraCE-21ka模拟,探究了晚全新世红水河形成...河流的形成及演变与区域环境和人类活动密切相关。红水河位于石羊河流域中游,是研究中国西北地区环境变化和古文化演变的重要地区。本文基于从红水河沿岸连续采集的5个剖面,结合历史地理资料和TraCE-21ka模拟,探究了晚全新世红水河形成与演变过程中的自然与人文因素,并通过分析HSH01、HSH04和HSH05剖面典型湖相层的沉积物粒度分布特征,揭示了晚全新世红水河水动力变化过程。研究发现,晚全新世西北地区呈现干旱化趋势,古湖泊武始泽完全萎缩,红水河现代河道开始下切形成。汉唐明清等强盛的中原王朝为加强对河西走廊的控制,采取屯田实边政策以及大兴水利,使得红水河流域农业迅速发展,农业用水激增,红水河流量进一步减少。晚全新世红水河流域沉积环境复杂,沉积相多变,2 ka BP以来红水河流域可能发生了强降水事件或洪水事件。展开更多
Geomorphometric modeling and mapping of Antarctic oases are promising for obtaining new quantitative knowledge about the topography of these unique landscapes and for the further use of morphometric information in Ant...Geomorphometric modeling and mapping of Antarctic oases are promising for obtaining new quantitative knowledge about the topography of these unique landscapes and for the further use of morphometric information in Antarctic research.Within the framework of a project to create a thematic physical-geographical scientific reference geomorphometric atlas of ice-free areas of Antarctica,we performed geomorphometric modeling and mapping of the Bunger Hills(Knox Coast,Wilkes Land,East Antarctica),one of the largest Antarctic oases.By processing a fragment of the Reference Elevation Model of Antarctica(REMA)covering the Bunger Hills and adjacent glaciers,we created,for the first time,a series of 37 medium-to large-scale maps of nine of the most scientifically important morphometric variables(i.e.,slope gradient,slope aspect,vertical curvature,horizontal curvature,maximal curvature,minimal curvature,catchment area,topographic wetness index,and stream power index).The morphometric maps describe the topography of the Bunger Hills in a quantitative,rigorous,and reproducible manner.New morphometric data can be useful for further geological,geomorphological,glaciological,ecological,and hydrological studies of this Antarctic oasis.展开更多
Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from v...Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from various perspectives.Peak intervisibility can provide the potential topographic information implied in the visual connectivity of peaks,however,its application in loess landform analysis remains unexplored.In this study,the interwoven sightlines among peaks,representing peak intervisibility,were extracted from the digital elevation model and simulated into a peak intervisibility network(PIN).Nine indices were proposed to quantify the PIN.Through a case study in Northern Shaanxi,China,three tasks were conducted,including,landform interpretation,spatial pattern mining,and landform classification.The main findings are as follows:(1)PIN responds to terrain morphology and is beneficial for loess landform interpretation.(2)The spatial patterns of PIN indices are heterogeneous and strongly coupled with the terrain morphologies,showing anisotropy and autocorrelation in spatial variations.(3)Using the light gradient boost machine classifier,the PIN index-based classification reaches a mean accuracy of 86.09%,an overall accuracy of 86%and a kappa coefficient of 0.84.These findings shed light on the applicability of PIN in loess landform analysis.Peak intervisibility not only enriches the theories and methodologies of relation-based digital terrain analysis,but also enhances our comprehension of loess landform genesis,morphology,distribution,and evolution.展开更多
文摘河流的形成及演变与区域环境和人类活动密切相关。红水河位于石羊河流域中游,是研究中国西北地区环境变化和古文化演变的重要地区。本文基于从红水河沿岸连续采集的5个剖面,结合历史地理资料和TraCE-21ka模拟,探究了晚全新世红水河形成与演变过程中的自然与人文因素,并通过分析HSH01、HSH04和HSH05剖面典型湖相层的沉积物粒度分布特征,揭示了晚全新世红水河水动力变化过程。研究发现,晚全新世西北地区呈现干旱化趋势,古湖泊武始泽完全萎缩,红水河现代河道开始下切形成。汉唐明清等强盛的中原王朝为加强对河西走廊的控制,采取屯田实边政策以及大兴水利,使得红水河流域农业迅速发展,农业用水激增,红水河流量进一步减少。晚全新世红水河流域沉积环境复杂,沉积相多变,2 ka BP以来红水河流域可能发生了强降水事件或洪水事件。
文摘Geomorphometric modeling and mapping of Antarctic oases are promising for obtaining new quantitative knowledge about the topography of these unique landscapes and for the further use of morphometric information in Antarctic research.Within the framework of a project to create a thematic physical-geographical scientific reference geomorphometric atlas of ice-free areas of Antarctica,we performed geomorphometric modeling and mapping of the Bunger Hills(Knox Coast,Wilkes Land,East Antarctica),one of the largest Antarctic oases.By processing a fragment of the Reference Elevation Model of Antarctica(REMA)covering the Bunger Hills and adjacent glaciers,we created,for the first time,a series of 37 medium-to large-scale maps of nine of the most scientifically important morphometric variables(i.e.,slope gradient,slope aspect,vertical curvature,horizontal curvature,maximal curvature,minimal curvature,catchment area,topographic wetness index,and stream power index).The morphometric maps describe the topography of the Bunger Hills in a quantitative,rigorous,and reproducible manner.New morphometric data can be useful for further geological,geomorphological,glaciological,ecological,and hydrological studies of this Antarctic oasis.
基金supported by the National Natural Science Foundation of China(Grant No.41771423)the Natural Science Foundation of Fujian Province(Grant No.2023J01421).
文摘Loess landforms in the Loess Plateau are typical landforms in arid and semiarid areas and have a significant impact on the environment and soil erosion.Quantitative analyses on loess landform have been employed from various perspectives.Peak intervisibility can provide the potential topographic information implied in the visual connectivity of peaks,however,its application in loess landform analysis remains unexplored.In this study,the interwoven sightlines among peaks,representing peak intervisibility,were extracted from the digital elevation model and simulated into a peak intervisibility network(PIN).Nine indices were proposed to quantify the PIN.Through a case study in Northern Shaanxi,China,three tasks were conducted,including,landform interpretation,spatial pattern mining,and landform classification.The main findings are as follows:(1)PIN responds to terrain morphology and is beneficial for loess landform interpretation.(2)The spatial patterns of PIN indices are heterogeneous and strongly coupled with the terrain morphologies,showing anisotropy and autocorrelation in spatial variations.(3)Using the light gradient boost machine classifier,the PIN index-based classification reaches a mean accuracy of 86.09%,an overall accuracy of 86%and a kappa coefficient of 0.84.These findings shed light on the applicability of PIN in loess landform analysis.Peak intervisibility not only enriches the theories and methodologies of relation-based digital terrain analysis,but also enhances our comprehension of loess landform genesis,morphology,distribution,and evolution.
