The measurement and modelling of rill erosion at angle of repose slopes in mine spoil

Abstract

The process of rill erosion causes significant amounts of sediment to be moved in both undisturbed and disturbed environments and can be a significant issue for agriculture as well as mining lands. Rills also often develop very quickly (from a single rainfall event to a season) and can develop into gullies if sufficient runoff is available to continue their development. This study examines the ability of a terrestrial laser scanner to quantify rills that have developed on fresh and homogeneous mine spoil on an angle of repose slope. It also examines the ability of the SIBERIA erosion model to simulate the rill's spatial and temporal behaviour. While there has been considerable work done examining rill erosion on rehabilitated mine sites and agricultural fields, little work has been done to examine rill development at angle of repose sites. Results show that while the overall hillslope morphology was captured by the laser scanner, with the morphology of the rills being broadly captured, the characteristics of the rills were not well defined. The digital elevation model created by the laser scanner failed to capture the rill thalwegs and tops of the banks, therefore delineating a series of ill defined longitudinal downslope depressions. These results demonstrate that an even greater density of points is needed to capture sufficient rill morphology. Nevertheless, SIBERIA simulations of the hillslope demonstrated that the model was able to capture rill behaviour in both space and time when correct model parameters were used. This result provides confidence in the SIBERIA model and its parameterization. The results demonstrate the sensitivity of the model to changes in parameters and the importance of the calibration process. Figure 2. Photograph of the study site (top) with a digital elevation model (0·2 m by 0·2 m grid) (bottom). This figure is available in colour online at www.interscience.wiley.com/journal/esplFigure 3. Initial hillslope used for the SIBERIA simulations. The digital elevation model grid size is 0·2 m by 0·2 m.Figure 4. Site layout showing scanner locations. Results Laser scanning of the slopeProximity to the studied slope was limited by the pond immediately in front of the slope. Initially, the instrument was set up at a location on the other side of the pond, approximately 300 m directly in front of the slope (Figure 4). This initial scan, while successfully capturing the gross morphology of the slope, generated a point cloud that was too sparse in relation to the rills. A second scan was done at a distance of approximately 100 m, but offset to the right of the slope (Figure 4). This location enabled the whole slope to be scanned at a higher resolution, and still without the presence of holes in the dataset created by features in the foreground obscuring more distant objects (known as 'occlusion effects ';Lim et al., 2005;Lichti and Gordon, 2004).I-Site was programmed so that it scanned the slope and surrounding area. This produced a point cloud consisting of approximately 76 000, points with the...

Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island of Elba using long-term ground-based lidar and photogrammetric SfM data by a UAV

“…Thus in combination with heavy rainfall, the slopes are often prone to erosion processes. Due to the rapid change of topography, such nonequilibrium landscapes (Hancock et al, 2008) can also provide sediments for subsequent geomorphic processes (e.g., mass movements or debris flows) and furthermore act as a source of heavy metal pollutants (Servida et al, 2009;Benvenuti et al, 1999) influencing e.g., the quality of drinking water. Investigations of the geomorphic process dynamic in this environment is thus of major importance for society, as they can show both potentially vulnerable areas or the success of recultivation projects.…”

“…As recultivated landscapes were set back, geomorphic processes start at "time zero" and thus can be analyzed ab initio (cf. Hancock et al, 2008).…”

“…Abellán et al, 2009;Schürch et al, 2011;Haas et al, 2012;d'Oleire-Oltmanns et al, 2012;Ouédraogo et al, 2014;Peter et al, 2014;Prosdocimi et al, 2015), as for the measurement of fluvial erosion or gullying on slopes of the Mediterranean region (Haas et al, 2011;d'Oleire-Oltmanns et al, 2012;Peter et al, 2014;2014) or on mining sites (cf. Hancock et al, 2008Hancock et al, , 2015Chen et al, 2015;Francioni et al, 2015). Beside these works, Tarolli (2014) gives a very detailed review of the applicability of the methods for the understanding of earth surface processes.…”

GIS-Based Detection of Gullies in Terrestrial LiDAR Data of the Cerro Llamoca Peatland (Peru)

“…DEMs are input to GIS-based geomorphometric analysis and the implementation of erosion models [11]. First, to generate such a submeter resolution DEM adequate data sources are necessary.…”

Soil Erosion on Abandoned Land in Andalusia: A Comparison of Interrill- and Rill Erosion Rates

“…This is considered to be the most important process of sediment erosion and soil loss [9,10]. As a result, the new rills can become persistent and form gullies, potentially constraining further land use [11][12][13][14]. Especially on fallow and shrub land, rills can develop without being disturbed by land management measures like ploughing.…”