Using terrestrial LiDAR to measure water erosion on stony plots under simulated rainfall     

Li Li  Mark A. Nearing  Mary H. Nichols  Viktor O. Polyakov  Michelle L. Cavanaugh 《地球表面变化过程与地形》2020,45(2):484-495

Terrestrial LiDAR scanning (TLS) technology is widely used to detect terrain elevation changes. This study examines the potential use of terrestrial LiDAR to measure erosion on small experimental plots at high resolution. Multitemporal TLS scans were conducted at six positions around plots (12 m²) with three slope treatments through 11 simulated rainfall applications. Surface elevation changes were quantified by comparing scans between rainfall simulations, and elevation changes greater than the level of detection were used to obtain volumetric change estimations. Erosion mass was estimated both by using soil bulk density and the density of sediment collected in runoff, and then compared to the erosion estimated from the runoff samples. Results showed: (1) with the aid of fixed reference controls in the form of concrete target surfaces of varying roughness, registration accuracy was better than 1 mm and mean level of change detection was less than 2.2 mm; (2) the average absolute relative errors of TLS-estimated eroded mass ranged from 6.8% to 31.8%, with greater values on 5% slope; (3) the TLS-estimated erosion accuracy was affected by erosion magnitude, the utilized material density and number of scan positions, and a grid size of 10 mm was found to be appropriate for this scale to estimate the volumetric changes; (4) the number of scan positions could be reduced to three while not significantly impacting volumetric change estimations; and (5) elevating the scanner resulted in much better accuracy for eroded mass estimations. This study suggests that using LiDAR to monitor soil erosion at the plot scale is feasible, and provides guidance about the level of accuracy one might expect in doing so. © 2019 John Wiley & Sons, Ltd.  相似文献   

基于多源激光点云融合的建筑物BIM建模     

刘亚坤  刘会云  李永强  赵上斌  杨亚伦 《地球信息科学学报》2021,23(5):763-772

墙体、窗户等单元构件是建筑物重要组成部分,精细提取其几何参数及位置信息对于完整表达建筑物整体模型具有重要意义.针对单一点云数据源无法获取建筑物单元构件相关参数并完整表达室内外模型重建问题,本文提出一整套融合室内外多源点云数据的BIM模型重建技术.为验证方法的有效性,选取河南理工大学测绘与国土信息工程学院教学楼为实验区域...  相似文献   

Testing slope effect on flow resistance equation for mobile bed rills          下载免费PDF全文

Costanza Di Stefano  Vito Ferro  Vincenzo Palmeri  Vincenzo Pampalone 《水文研究》2018,32(5):664-671

In this paper, a recently theoretically deduced rill flow resistance equation, based on a power‐velocity profile, is tested experimentally on plots of varying slopes in which mobile bed rills are incised. Initially, measurements of flow velocity, water depth, cross‐sectional area, wetted perimeter and bed slope conducted in 106 reaches of rills incised on an experimental plot having a slope of 14% were used to calibrate the flow resistance equation. Then, the relationship between the velocity profile parameter Γ, the channel slope, and the flow Froude number, which was calibrated using the 106 rill reach data, was tested using measurements carried out in plots having slopes of 22% and 9%. The measurements carried out in the latter slope conditions confirmed that (a) the Darcy–Weisbach friction factor can be accurately estimated using the proposed theoretical approach, and (b) the data were supportive of the slope independence hypothesis of rill velocity stated by Govers.  相似文献   

Notes     

《The Journal of geography》2012,111(6):279-288

Abstract

The concept of correlation is becoming increasingly important to students of all ages as the use of electronic data base technology becomes more common. Data maps offer a significant and new format for secondary students to use along with tables of values and scatter plots as they learn and apply the correlation concept. Data maps are particularly effective in promoting the interdisciplinary treatment of important content by allowing students to interpret social or physical relationships within the geographic context in which they arise.  相似文献