The rates and spatial patterns of annual riverbank erosion revealed through terrestrial laser‐scanner surveys of the South River,Virginia     

Michael A. O'Neal  James E. Pizzuto 《地球表面变化过程与地形》2011,36(5):695-701

Between a.d. 2006 and 2008, we completed annual surveys of two mercury‐contaminated eroding banks, one forested and the other grass covered, along the gravel‐bed, bedrock South River in Virginia. Gridded digital terrain models with a resolution of 0·05 m were created from bank topography data collected using a terrestrial laser scanner. Model comparisons indicate that the forested bank retreated nearly 1 m around two leaning trees, while elsewhere the extent of bank retreat was negligible. On the grassy bank, retreat was controlled by the creation of small overhanging clumps of turf at the top of the bank, their occasional failure, and the ultimate removal of failed debris from the bank toe. Partial autocorrelation analysis of vertically integrated bank retreat demonstrates that bank profile erosion is virtually uncorrelated at horizontal distances greater than about 1 m on both banks, a length scale of approximately half the bank height. This extensive streamwise variability suggests that widely spaced profile data cannot adequately represent bank erosion at these sites. Additional analysis of our comprehensive spatial data also indicates that traditional bank profile surveys with any spacing greater than 1 m would result in measurement errors exceeding 10%, an important conclusion for assessing annual rates of mercury loading into the South River from bank erosion. Our results suggest that three‐dimensional gridded bare‐earth models of bank topography may be required to accurately measure annual bank retreat in similar river systems. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Interactions between river flows and colonizing vegetation on a braided river: exploring spatial and temporal dynamics in riparian vegetation cover using satellite data     

W. Bertoldi  N. A. Drake  A. M. Gurnell 《地球表面变化过程与地形》2011,36(11):1474-1486

Field, laboratory, and numerical modelling research are increasingly demonstrating the potential of riparian tree colonization and growth to influence fluvial dynamics and the evolution of fluvial landforms. This paper jointly analyses multi‐temporal, multispectral ASTER data, continuous river stage and discharge data, and field observations of the growth rates of the dominant riparian tree species (Populus nigra) along a 21 km reach of the Tagliamento River, Italy. Research focuses on the period 2004–2009, during which there was a bankfull flood on 24 October 2004, followed by 2 years with low water levels, nearly 2 years with only modest flow pulses, and then a final period from 15 August 2008 that included several intermediate to bankfull flow events. This study period of increasing flow disturbance allows the exploration of vegetation dynamics within the river's active corridor under changing flow conditions. The analysis demonstrates the utility of ASTER data for investigating vegetation dynamics along large fluvial corridors and reveals both spatial and temporal variations in the expansion, coalescence, and erosion of vegetated patches within the study reach. Changes in the extent of the vegetated area and its dynamics vary along the study reach. In sub‐reaches where riparian tree growth is vigorous, the vegetated area expands rapidly during time periods without channel‐shaping flows, and is subsequently able to resist erosion by bankfull floods. In contrast, in sub‐reaches where tree growth is less vigorous, the vegetated area expands at a slower rate and is more readily re‐set by bankfull flood events. This illustrates that the rate of growth of riparian trees is crucial to their ability to contribute actively to river corridor dynamics. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Mapping of erosion rates in marly badlands based on a coupling of anatomical changes in exposed roots with slope maps derived from LiDAR data     

Jérôme Lopez Saez  Christophe Corona  Markus Stoffel  Georges Rovéra  Laurent Astrade  Frédéric Berger 《地球表面变化过程与地形》2011,36(9):1162-1171

Black marls form very extensive outcrops in the Alps and constitute some of the most eroded terrains, thus causing major problems of sedimentation in artificial storage systems (e.g. reservoirs) and river systems. In the experimental catchments near Draix (France), soil erosion rates have been measured in the past at the plot scale through a detailed monitoring of surface elevation changes and at the catchment scale through continuous monitoring of sediment yield in traps at basin outlets. More recently, erosion rates have been determined by means of dendrogeomorphic techniques in three monitored catchments of the Draix basin. A total of 48 exposed roots of Scots pine have been sampled and anatomical variations in annual growth rings resulting from denudation analysed. At the plot scale, average medium‐term soil erosion rates derived from exposed roots vary between 1·8 and 13·8 mm yr^?1 (average: 5·9 mm yr^?1) and values are significantly correlated with slope angle. The dendrogeomorphic record of point‐scale soil erosion rates matches very well with soil erosion rates measured in the Draix basins. Based on the point‐scale measurements and dendrogeomorphic results obtained at the point scale, a linear regression model involving slope angle was derived and coupled to high‐resolution slope maps obtained from a LiDAR‐generated digital elevation model so as to generate high‐resolution soil erosion maps. The resulting regression model is statistically significant and average soil erosion rates obtained from the areal erosion map (5·8, 5·2 and 6·2 mm yr^?1 for the Roubine, Moulin and Laval catchments, respectively) prove to be well in concert with average annual erosion rates measured in traps at the outlet of these catchments since 1985 (6·3, 4·1 and 6·4 mm yr^?1). This contribution demonstrates that dendrogeomorphic analyses of roots clearly have significant potential and that they are a powerful tool for the quantification and mapping of soil erosion rates in areas where measurements of past erosion is lacking. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Terrestrial laser scanning to estimate plot-level forest canopy fuel properties     

Mariano García  F. Mark Danson  David Riaño  Emilio Chuvieco  F. Alberto Ramirez  Vishal Bandugula 《International Journal of Applied Earth Observation and Geoinformation》2011

This paper evaluates the potential of a terrestrial laser scanner (TLS) to characterize forest canopy fuel characteristics at plot level. Several canopy properties, namely canopy height, canopy cover, canopy base height and fuel strata gap were estimated. Different approaches were tested to avoid the effect of canopy shadowing on canopy height estimation caused by deployment of the TLS below the canopy. Estimation of canopy height using a grid approach provided a coefficient of determination of R² = 0.81 and an RMSE of 2.47 m. A similar RMSE was obtained using the 99th percentile of the height distribution of the highest points, representing the 1% of the data, although the coefficient of determination was lower (R² = 0.70). Canopy cover (CC) was estimated as a function of the occupied cells of a grid superimposed upon the TLS point clouds. It was found that CC estimates were dependent on the cell size selected, with 3 cm being the optimum resolution for this study. The effect of the zenith view angle on CC estimates was also analyzed. A simple method was developed to estimate canopy base height from the vegetation vertical profiles derived from an occupied/non-occupied voxels approach. Canopy base height was estimated with an RMSE of 3.09 m and an R² = 0.86. Terrestrial laser scanning also provides a unique opportunity to estimate the fuel strata gap (FSG), which has not been previously derived from remotely sensed data. The FSG was also derived from the vegetation vertical profile with an RMSE of 1.53 m and an R² = 0.87.  相似文献   

3D modeling of light interception in heterogeneous forest canopies using ground-based LiDAR data     

Dimitry Van der Zande  Jan Stuckens  Willem W. Verstraeten  Simone Mereu  Bart Muys  Pol Coppin 《International Journal of Applied Earth Observation and Geoinformation》2011

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基于LiDAR和航空影像的地震灾害倒塌建筑物信息提取   总被引：1，自引：0，他引：1  

于海洋  程钢  张育民  卢小平 《国土资源遥感》2011,(3):77-81

地震灾害损失评估是震后展开救灾工作的重要环节.快速、准确地获取震后损毁建筑物信息能够为灾区减灾、救灾工作提供有效的支持.高分辨率航空遥感是灾害监测的重要技术手段,但其信息自动提取的精度受到一定的限制.近年来新出现的LiDAR技术能够提供地面目标的高程信息,可应用于复杂环境下倒塌建筑物信息的提取.研究中采用航空遥感数据和...  相似文献   

基于多分辨率分析的LiDAR数据处理与可视化     

梁静  范洪冬  邓喀中 《测绘工程》2011,20(4):50-54

基于多分辨率分析的数据滤波算法对于地形变化单一但地物和地形区别明显的场景,地形多变但连续且地物和地形区别明显的场景具有非常优越的滤波效果.研究基于多分辨率分析的数据滤波算法的基本原理,在Visual C++6.0平台上编程实现该算法,建立LiDAR数据处理与可视化系统,详细介绍各功能模块的实现方法和功能,实现由LiDA...  相似文献   

机载LIDAR技术在快速生产高精度DEM中的应用   总被引：1，自引：1，他引：0  

王雪娇  洪友堂 《北京测绘》2011,(4):46-48,33

论述了机载LIDAR系统的组成与工作原理,简述了生产中利用机载LIDAR数据生成DEM的流程及原理分析,并结合数据生产DEM,分析其精度.  相似文献   

一种机载LiDAR条带平差最小二乘匹配算法     

王丽英  刘正军 《遥感学报》2011,15(3):554-567

基于七参数正形变换的数据驱动模型实现了机载LiDAR条带平差,算法借鉴了Robert(2004)的最小二乘表面匹 配思想,通过引入高斯–马尔科夫模型改进了原有算法,得到未知参数的最小无偏方差估计。实验采用两组实测数 据,分别考察了引入高斯–马尔科夫模型的必要性、算法效率以及迭代收敛性和算法精度。实验表明：(1)剖面检查吻 合且精度一致;(2)TerraMatch量测匹配精度,理想数据高程匹配误差小于0.05 m,数据质量不理想时误差稍大,但均 能成功匹配。  相似文献   

机载LiDAR点云数据的建筑物重建研究   总被引：5，自引：2，他引：3  

曾齐红  毛建华  李先华  刘学锋 《武汉大学学报(信息科学版)》2011,(3):321-324,328

提出了利用机载LiDAR点云数据进行复杂平面建筑物重建的方法。首先,将提取出的建筑物点云聚类到不同的平面点集;然后,对各个平面点集进行平面拟合,采用平面相交确定平面边界,并解算出各平面边界角点的三维坐标,从而重建建筑物模型。某区域的机载LiDAR点云数据的实验结果表明,该方法能有效地重建出较复杂的平面建筑物。  相似文献