The landscape pattern metrics can quantitatively describe the characteristics of landscape pattern and are widely used in various fields of landscape ecology.Due to the lack of vertical information,2D landscape metric...The landscape pattern metrics can quantitatively describe the characteristics of landscape pattern and are widely used in various fields of landscape ecology.Due to the lack of vertical information,2D landscape metrics cannot delineate the vertical characteristics of landscape pattern.Based on the point clouds,a high-resolution voxel model and several voxel-based 3D landscape metrics were constructed in this study and 3D metrics calculation results were compared with that of 2D metrics.The results showed that certain quantifying difference exists between 2D and 3D landscape metrics.For landscapes with different components and spatial configurations,significant difference was disclosed between 2D and 3D landscape metrics.3D metrics can better reflect the real spatial structure characteristics of the landscape than 2D metrics.展开更多
船载移动激光雷达扫描系统由脉冲激光源、测距探测接收器、系统控制处理器和光机扫描器组成,并集成定位定姿系统(Position and Orientation System,POS)。本文以自主研发的船载激光扫描仪为研究对象,阐述了扫描系统的软硬件组成与工作流...船载移动激光雷达扫描系统由脉冲激光源、测距探测接收器、系统控制处理器和光机扫描器组成,并集成定位定姿系统(Position and Orientation System,POS)。本文以自主研发的船载激光扫描仪为研究对象,阐述了扫描系统的软硬件组成与工作流程,并对实验结果进行了精度评定。实验表明,本文设计的船载移动三维激光扫描系统能有效准确地获取目标物的三维点云数据,未来可在海岸带海岛礁测绘、港口码头测量、近岸工程变形监测中发挥重大作用。展开更多
Star dune is one typical kind of aeolian geomorphology in global sand seas.It has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian pyramid.The landform p...Star dune is one typical kind of aeolian geomorphology in global sand seas.It has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian pyramid.The landform pattern of star dune is mainly dominated by factors such as regional wind regime,sand availability,and local topography.Star dunes grow vertically as they accumulate sand brought in from different directions;however,little is known regarding morphologic changes during this process.The stability of star dunes based on quantitative data is another unsolved question due to the limitation in measuring equipment or other factors.And whether the star dune can grow into star sand hills is another scientific problem which needs to be discussed.In this paper,the heightening development process and morphological changes of star dunes were monitored in Mingsha Mountain of Dunhuang with the 3D laser scanner.Results show that the star dunes in Mingsha Mountain were formed by a group of relatively steady winds,which were northwest,northeast and south winds.With the increase of the height of the star dunes,the morphological parameters of the dune,such as the volume and bottom area,did not show regular changes.The surface erosion of both Dune 1 and Dune 2 during the observation period was closely related to the regional wind conditions.During the growth of the star dunes,the overall trend of the dunes was relatively steady and the dune shape maintained its stability although the aspect and slope of the sand dunes changed,indicating that the stability of star dune was not complete and was dynamic.Moreover,the variation range of the dune slope was proportional to the volume change of the dune.展开更多
The Dunhuang–Golmud railway passes through different deserts in arid areas,especially drifting-sand desert and sandy-gravel Gobi.The near-surface wind environment and wind-sand transport process vary due to different...The Dunhuang–Golmud railway passes through different deserts in arid areas,especially drifting-sand desert and sandy-gravel Gobi.The near-surface wind environment and wind-sand transport process vary due to different external factors,such as topography,vegetation,and regional climate,resulting in evident spatial differences in surface erosion and deposition.Consequently,the measures for preventing wind-sand hazards will differ.However,the mechanism and control theory of sand damage remain poorly understood.In this study,we used meteorological observation,three-dimensional(3D)laser scanning,and grain-size analysis to compare and evaluate the spatial distribution of wind conditions,sand erosion and deposition patterns,and grain composition in the drifting-sand desert and sandy-gravel Gobi along the Dunhuang–Golmud railway in China.Results show that the annual mean wind speed,the frequency of sand-driving wind,and the drift potential of sandy-gravel Gobi are higher than those of drifting-sand desert,indicating a greater wind strength in the sandy-gravel Gobi,which exhibits spatial heterogeneity in wind conditions.The major sediment components in sandy-gravel Gobi are very fine sand,fine sand,and medium sand,and that in drifting-sand desert are very fine sand and fine sand.We found that the sediment in the sandy-gravel Gobi is coarser than that in the drifting-sand desert based on mean grain size and sediment component.The spatial distributions of sand erosion and deposition in the sandy-gravel Gobi and drifting-sand desert are consistent,with sand deposition mainly on the west side of the railway and sand erosion on the east side of the railway.The area of sand deposition in the drifting-sand desert accounts for 75.83%of the total area,with a mean deposition thickness of 0.032 m;while the area of sand deposition in the sandy-gravel Gobi accounts for 65.31%of the total area,with a mean deposition thickness of 0.028 m,indicating greater deposition amounts in the drifting-sand desert due to the presence of more fine sediment components.However,the sand deposition is more concentrated with a greater thickness on the embankment and track in the sandy-gravel Gobi and is dispersed with a uniform thickness in the drifting-sand desert.The sand deposition on the track of the sandy-gravel Gobi mainly comes from the east side of the railway.The results of this study are helpful in developing the preventive measures and determining appropriate selection and layout measures for sand control.展开更多
文摘The landscape pattern metrics can quantitatively describe the characteristics of landscape pattern and are widely used in various fields of landscape ecology.Due to the lack of vertical information,2D landscape metrics cannot delineate the vertical characteristics of landscape pattern.Based on the point clouds,a high-resolution voxel model and several voxel-based 3D landscape metrics were constructed in this study and 3D metrics calculation results were compared with that of 2D metrics.The results showed that certain quantifying difference exists between 2D and 3D landscape metrics.For landscapes with different components and spatial configurations,significant difference was disclosed between 2D and 3D landscape metrics.3D metrics can better reflect the real spatial structure characteristics of the landscape than 2D metrics.
文摘船载移动激光雷达扫描系统由脉冲激光源、测距探测接收器、系统控制处理器和光机扫描器组成,并集成定位定姿系统(Position and Orientation System,POS)。本文以自主研发的船载激光扫描仪为研究对象,阐述了扫描系统的软硬件组成与工作流程,并对实验结果进行了精度评定。实验表明,本文设计的船载移动三维激光扫描系统能有效准确地获取目标物的三维点云数据,未来可在海岸带海岛礁测绘、港口码头测量、近岸工程变形监测中发挥重大作用。
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0608403-1)the National Natural Science Foundation of China(Grant No.41871016)+1 种基金the Opening Research Foundation of the Key Laboratory of Desert and Desertification,CAS(KLDD-2020-015)the Science and Technology Research Project of China Railway First Survey and Design Institute Group Co.,Ltd.(2019-10)。
文摘Star dune is one typical kind of aeolian geomorphology in global sand seas.It has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian pyramid.The landform pattern of star dune is mainly dominated by factors such as regional wind regime,sand availability,and local topography.Star dunes grow vertically as they accumulate sand brought in from different directions;however,little is known regarding morphologic changes during this process.The stability of star dunes based on quantitative data is another unsolved question due to the limitation in measuring equipment or other factors.And whether the star dune can grow into star sand hills is another scientific problem which needs to be discussed.In this paper,the heightening development process and morphological changes of star dunes were monitored in Mingsha Mountain of Dunhuang with the 3D laser scanner.Results show that the star dunes in Mingsha Mountain were formed by a group of relatively steady winds,which were northwest,northeast and south winds.With the increase of the height of the star dunes,the morphological parameters of the dune,such as the volume and bottom area,did not show regular changes.The surface erosion of both Dune 1 and Dune 2 during the observation period was closely related to the regional wind conditions.During the growth of the star dunes,the overall trend of the dunes was relatively steady and the dune shape maintained its stability although the aspect and slope of the sand dunes changed,indicating that the stability of star dune was not complete and was dynamic.Moreover,the variation range of the dune slope was proportional to the volume change of the dune.
基金This research was supported by the National Natural Science Foundation of China(42171083,41871016)the Natural Science Foundation of Gansu Province,China(22JR5RA066).
文摘The Dunhuang–Golmud railway passes through different deserts in arid areas,especially drifting-sand desert and sandy-gravel Gobi.The near-surface wind environment and wind-sand transport process vary due to different external factors,such as topography,vegetation,and regional climate,resulting in evident spatial differences in surface erosion and deposition.Consequently,the measures for preventing wind-sand hazards will differ.However,the mechanism and control theory of sand damage remain poorly understood.In this study,we used meteorological observation,three-dimensional(3D)laser scanning,and grain-size analysis to compare and evaluate the spatial distribution of wind conditions,sand erosion and deposition patterns,and grain composition in the drifting-sand desert and sandy-gravel Gobi along the Dunhuang–Golmud railway in China.Results show that the annual mean wind speed,the frequency of sand-driving wind,and the drift potential of sandy-gravel Gobi are higher than those of drifting-sand desert,indicating a greater wind strength in the sandy-gravel Gobi,which exhibits spatial heterogeneity in wind conditions.The major sediment components in sandy-gravel Gobi are very fine sand,fine sand,and medium sand,and that in drifting-sand desert are very fine sand and fine sand.We found that the sediment in the sandy-gravel Gobi is coarser than that in the drifting-sand desert based on mean grain size and sediment component.The spatial distributions of sand erosion and deposition in the sandy-gravel Gobi and drifting-sand desert are consistent,with sand deposition mainly on the west side of the railway and sand erosion on the east side of the railway.The area of sand deposition in the drifting-sand desert accounts for 75.83%of the total area,with a mean deposition thickness of 0.032 m;while the area of sand deposition in the sandy-gravel Gobi accounts for 65.31%of the total area,with a mean deposition thickness of 0.028 m,indicating greater deposition amounts in the drifting-sand desert due to the presence of more fine sediment components.However,the sand deposition is more concentrated with a greater thickness on the embankment and track in the sandy-gravel Gobi and is dispersed with a uniform thickness in the drifting-sand desert.The sand deposition on the track of the sandy-gravel Gobi mainly comes from the east side of the railway.The results of this study are helpful in developing the preventive measures and determining appropriate selection and layout measures for sand control.
