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

Abstract

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 m 2 ) 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.

Can the models keep up with the data? Possibilities of soil and soil surface assessment techniques in the context of process based soil erosion models – A Review

“…These datasets and the quantification of soil loss help to assess and understand the water erosion mechanisms and the spatial and temporal dimension of the soil erosion processes taking place on the slope to catchment scale (Cândido et al, 2020;Eltner et al, 2018). LiDAR, despite the higher time and cost expenditure, proves a feasible tool for change detection (Li et al, 2020a), helping to improve the understanding of soil erosion forms, as soil crusts (Hu et al, 2020a) or rill characteristics (Vinci et al, 2015). Jiang et al (2020) monitor rilling on an artificial plot via LiDAR and SfM.…”

Response to Reviewer #2

“…These datasets and the quantification of soil loss help to assess and understand the water erosion mechanisms and the spatial and temporal dimension of the soil erosion processes taking place on the slope to catchment scale (Cândido et al, 2020;Eltner et al, 2018). LiDAR, despite the higher time and cost expenditure, proves a feasible tool for change detection (Li et al, 2020a), helping to improve the understanding of soil erosion forms, as soil crusts (Hu et al, 2020a) or rill characteristics (Vinci et al, 2015). Jiang et al (2020) monitor rilling on an artificial plot via LiDAR and SfM.…”

Monitoring soil erosion on field slopes by terrestrial laser scanning and structure‐from‐motion

“…Among laser scanning techniques, TLS has been widely utilized for erosion monitoring (e.g., Bailey et al, 2022; Goodwin et al, 2017; Lane et al, 1994; Li et al, 2020; Milan et al, 2007; Telling et al, 2017; Vinci et al, 2015), while monitoring results have been verified and often used as a benchmark (Gao et al, 2021b; Gao et al, 2021a; Yang et al, 2021). Li et al (2020) verified the accuracy of TLS in slope erosion monitoring based on laboratory experiments and packed soil. The transferability of the findings in that study was, however, constrained by the fact that erosion processes developed on packed soil are rather different from those on natural slopes.…”

“…Sediment traps and erosion pins are invasive that disturb the micro‐topography and soil structure; however, their measurements are subject to a low spatial resolution (Neugirg et al, 2016). Erosion measurements achieved from field plots were normally collected at the plot outlet, which leads to a loss of information on sediment transport (Li et al, 2020). The tracer method is capable of detecting the erosion/deposition processes but its application is constrained by the intensive time and labor requirements (Li et al, 2021b; Li et al, 2021a).…”

“…The laser scanner emits laser beams and receives the returns from objects to form dense 3D point clouds based on the laser-emitting angle and echo signals (Li et al, 2020). Among laser scanning techniques, TLS has been widely utilized for erosion monitoring (e.g., Bailey et al, 2022;Goodwin et al, 2017;Lane et al, 1994;Li et al, 2020;Milan et al, 2007;Telling et al, 2017;Vinci et al, 2015), while monitoring results have been verified and often used as a benchmark (Gao et al, 2021b;Gao et al, 2021a;Yang et al, 2021) vidual experiments (i.e., consecutive sediment yield) and cumulative sediment yield from hillslopes. Evidently, the use of TLS to monitor erosion processes and its accuracy verification have been well established, facilitating a wide use of the technique.…”