scholarly journals Studying the influence of livestock pressure on gully erosion in rangelands of SW Spain by means of the UAV+SfM workflow

2018 ◽  
pp. 66-88
Author(s):  
Álvaro Gómez Gutiérrez ◽  
Susanne Schnabel ◽  
Francisco Lavado Contador ◽  
José Juan De Sanjosé ◽  
Alan D. J. Atkinson ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Spatial Scales ◽  
Degradation Process ◽  
Gully Erosion ◽  
Valley Bottom ◽  
Sw Spain ◽  
Aerial Vehicles ◽  
Agrosilvopastoral Systems ◽  
Small Valley

Gully erosion in agrosilvopastoral systems of SW Spain represents a common degradation process, but has been hardly analysed. The suitability of using the Unmanned Aerial Vehicles (UAV) and Structure from Motion photogrammetry (SfM) workflow to map small valley-bottom gullies in these landscapes was tested. The results showed centimetre-level accuracy. Observed strengths and limitations of the UAV+SfM workflow in the study areas are discussed. The resulting cartography allowed mapping soil erosion forms at outstanding spatial scales. All study areas showed evidences of degradation.

Spatio-temporal dynamics of erosion and deposition in a partially restored valley-bottom gully

2021 ◽  
Author(s):  
Alberto Alfonso-Torreño ◽  
Álvaro Gómez-Gutiérrez ◽  
Susanne Schnabel
Keyword(s):  
Temporal Dynamics ◽  
Land Use Changes ◽  
Degradation Process ◽  
Gully Erosion ◽  
Aerial Images ◽  
Negative Consequences ◽  
Valley Bottom ◽  
Erosion And Deposition ◽  
Check Dams ◽  
Spatio Temporal

<p>Soil erosion by water is a frequent soil degradation process in rangelands of SW Spain. The two main erosive processes in these areas are sheetwash erosion in hillslopes and gully erosion due to concentrated flow in valley bottoms. Land use changes and overgrazing play a key role in the genesis and development of gullies and gully erosion is a frequent process with negative consequences at the valley bottoms of these landscapes.</p><p>The development of new techniques allows monitoring of gully dynamics with an increase at spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland with a savannah-like vegetation cover that was partially restored in February 2017. Restoration activities included check dams (gabion weirs and fascines) and livestock exclosure by fencing. The objectives of this study were: (1) to analyze the effectiveness of the restoration measures, (2) to study erosion and deposition dynamics before and after the restoration activities, (3) to examine the role of micro-morphology on the observed topographic changes and (4) to compare the current and recent channel dynamics with previous studies conducted in the same study area through different methods and spatio-temporal scales, quantifying medium-term changes. Topographic changes were estimated using multi-temporal high-resolution DEMs produced using Structure-from-Motion (SfM) photogrammetry and aerial images acquired by a fixed-wing Unmanned Aerial Vehicle (UAV). DEMs and orthophotographs with a Ground Sampling Distance of 0.02 m were produced by means of SfM photogrammetric techniques. The average Root Mean Square Error (RMSE) estimated during the SfM processing was 0.03 m.</p><p>The performance of the restoration activities was satisfactory to control gully erosion. Check dams were effective favoring sediment deposition and reducing lateral bank erosion. Nevertheless, erosion was observed immediately downstream in 9% of the check dams. Livestock exclosure in the most degraded area promoted the stabilization of bank headcuts and revegetation. The sediments retained behind check dams reduced the longitudinal slope gradient of the channel bed and established a positive feedback mechanism for channel revegetation.</p><p><strong>Keywords</strong>: gully erosion, restoration, topographic change, UAV+SfM, rangeland.</p>

scholarly journals Operational Framework for Rapid, Very-high Resolution Mapping of Glacial Geomorphology Using Low-cost Unmanned Aerial Vehicles and Structure-from-Motion Approach

2019 ◽  
Vol 11 (1) ◽  
pp. 65 ◽  
Author(s):  
Marek W. Ewertowski ◽  
Aleksandra M. Tomczyk ◽  
David J. A. Evans ◽  
David H. Roberts ◽  
Wojciech Ewertowski
Keyword(s):  
High Resolution ◽  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Low Cost ◽  
Control Point ◽  
Glacial Geomorphology ◽  
High Resolution Mapping ◽  
Aerial Vehicles ◽  
Resolution Mapping ◽  
Very High

This study presents the operational framework for rapid, very-high resolution mapping of glacial geomorphology, with the use of budget Unmanned Aerial Vehicles and a structure-from-motion approach. The proposed workflow comprises seven stages: (1) Preparation and selection of the appropriate platform; (2) transport; (3) preliminary on-site activities (including optional ground-control-point collection); (4) pre-flight setup and checks; (5) conducting the mission; (6) data processing; and (7) mapping and change detection. The application of the proposed framework has been illustrated by a mapping case study on the glacial foreland of Hørbyebreen, Svalbard, Norway. A consumer-grade quadcopter (DJI Phantom) was used to collect the data, while images were processed using the structure-from-motion approach. The resultant orthomosaic (1.9 cm ground sampling distance—GSD) and digital elevation model (7.9 cm GSD) were used to map the glacial-related landforms in detail. It demonstrated the applicability of the proposed framework to map and potentially monitor detailed changes in a rapidly evolving proglacial environment, using a low-cost approach. Its coverage of multiple aspects ensures that the proposed framework is universal and can be applied in a broader range of settings.

Using UAVs to Manage Archaeological Heritage

2020 ◽  
pp. 247-264
Author(s):  
Erin Friedman ◽  
Cory Look ◽  
Matthew Brown
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Heritage Management ◽  
Aerial Imagery ◽  
Surface Model ◽  
Archaeological Research ◽  
Archaeological Heritage ◽  
Sugar Plantation ◽  
Aerial Vehicles ◽  
Archaeological Excavations

This chapter explores the use of UAVs (unmanned aerial vehicles) for the use of archaeological investigations and heritage management at the historic sugar plantation of Betty’s Hope, Antigua. While the acquisition of low flying aerial imagery, such as kite photography, has been common practice within archaeological research, recent software innovations coupling photogrammetry and UAV technologies are providing new tools for exploration. Two different approaches for UAV acquisition are explored in this chapter: the first for use within archaeological excavations and the second for use at studying the landscape. Both have particular implications for heritage management, as the use of structure from motion (SfM) methodology coupled with aerial imagery can be used to produce an accurate 3D surface model of the site that is akin to site scanners and LiDAR technology. The important differences and limitations to these technologies are discussed.

scholarly journals Advances in mapping sub-canopy snow depth with unmanned aerial vehicles using structure from motion and lidar techniques

2019 ◽  
Author(s):  
Phillip Harder ◽  
John W. Pomeroy ◽  
Warren D. Helgason
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Snow Depth ◽  
Point Clouds ◽  
Airborne Lidar ◽  
Canadian Prairie ◽  
Widespread Application ◽  
Aerial Vehicles ◽  
Wide Range ◽  
Consistent Error

Abstract. Vegetation has a tremendous influence on snow processes and snowpack dynamics yet remote sensing techniques to resolve the spatial variability of sub-canopy snow depth are lacking. Unmanned Aerial Vehicles (UAV) have had recent widespread application to capture high resolution information on snow processes and are herein applied to the sub-canopy snow depth challenge. Previous demonstrations of snow depth mapping with UAV Structure from Motion (SfM) and airborne-lidar have focussed on non-vegetated surfaces or reported large errors in the presence of vegetation. In contrast, UAV-lidar systems have high-density point clouds, measure returns from a wide range of scan angles, and so have a greater likelihood of successfully sensing the sub-canopy snow depth. The effectiveness of UAV-lidar and UAV-SfM in mapping snow depth in both open and forested terrain was tested in a 2019 field campaign in the Canadian Rockies Hydrological Observatory, Alberta and at Canadian Prairie sites near Saskatoon, Saskatchewan, Canada. Only UAV-lidar could successfully measure the sub-canopy snow surface with reliable sub-canopy point coverage, and consistent error metrics (RMSE

scholarly journals Habitat suitability maps for juvenile tri-spine horseshoe crabs in Japanese intertidal zones: A model approach using unmanned aerial vehicles and the Structure from Motion technique

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244494
Author(s):  
Akihiko Koyama ◽  
Taiga Hirata ◽  
Yuki Kawahara ◽  
Hiroki Iyooka ◽  
Haruka Kubozono ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Habitat Suitability ◽  
Tidal Range ◽  
Suitable Habitat ◽  
Intertidal Zones ◽  
Intertidal Flats ◽  
Aerial Vehicles ◽  
Short Period ◽  
Suitability Maps

The tri-spine horseshoe crab, Tachypleus tridentatus, is a threatened species that inhabits coastal areas from South to East Asia. A Conservation management system is urgently required for managing its nursery habitats, i.e., intertidal flats, especially in Japan. Habitat suitability maps are useful in drafting conservation plans; however, they have rarely been prepared for juvenile T. tridentatus. In this study, we examined the possibility of constructing robust habitat suitability models (HSMs) for juveniles based on topographical data acquired using unmanned aerial vehicles and the Structure from Motion (UAV-SfM) technique. The distribution data of the juveniles in the Tsuyazaki and Imazu intertidal flats from 2017 to 2019 were determined. The data were divided into a training dataset for HSM construction and three test datasets for model evaluation. High accuracy digital surface models were built for each region using the UAV-SfM technique. Normalized elevation was assessed by converting the topographical models that consider the tidal range in each region, and the slope was calculated based on these models. Using the training data, HSMs of the juveniles were constructed with normalized elevation and slope as the predictor variables. The HSMs were evaluated using the test data. The results showed that HSMs exhibited acceptable discrimination performance for each region. Habitat suitability maps were built for the juveniles in each region, and the suitable areas were estimated to be approximately 6.1 ha of the total 19.5 ha in Tuyazaki, and 3.7 ha of the total 7.9 ha area in Imazu. In conclusion, our findings support the usefulness of the UAV-SfM technique in constructing HSMs for juvenile T. tridentatus. The monitoring of suitable habitat areas for the juveniles using the UAV-SfM technique is expected to reduce survey costs, as it can be conducted with fewer investigators over vast intertidal zones within a short period of time.

scholarly journals Improving sub-canopy snow depth mapping with unmanned aerial vehicles: lidar versus structure-from-motion techniques

2020 ◽  
Vol 14 (6) ◽  
pp. 1919-1935
Author(s):  
Phillip Harder ◽  
John W. Pomeroy ◽  
Warren D. Helgason
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Snow Depth ◽  
Airborne Lidar ◽  
Snow Surface ◽  
Widespread Application ◽  
Large Variability ◽  
Error Metrics ◽  
Aerial Vehicles ◽  
Wide Range

Abstract. Vegetation has a tremendous influence on snow processes and snowpack dynamics, yet remote sensing techniques to resolve the spatial variability of sub-canopy snow depth are not always available and are difficult from space-based platforms. Unmanned aerial vehicles (UAVs) have had recent widespread application to capture high-resolution information on snow processes and are herein applied to the sub-canopy snow depth challenge. Previous demonstrations of snow depth mapping with UAV structure from motion (SfM) and airborne lidar have focussed on non-vegetated surfaces or reported large errors in the presence of vegetation. In contrast, UAV-lidar systems have high-density point clouds and measure returns from a wide range of scan angles, increasing the likelihood of successfully sensing the sub-canopy snow depth. The effectiveness of UAV lidar and UAV SfM in mapping snow depth in both open and forested terrain was tested in a 2019 field campaign at the Canadian Rockies Hydrological Observatory, Alberta, and at Canadian prairie sites near Saskatoon, Saskatchewan, Canada. Only UAV lidar could successfully measure the sub-canopy snow surface with reliable sub-canopy point coverage and consistent error metrics (root mean square error (RMSE) <0.17 m and bias −0.03 to −0.13 m). Relative to UAV lidar, UAV SfM did not consistently sense the sub-canopy snow surface, the interpolation needed to account for point cloud gaps introduced interpolation artefacts, and error metrics demonstrated relatively large variability (RMSE<0.33 m and bias 0.08 to −0.14 m). With the demonstration of sub-canopy snow depth mapping capabilities, a number of early applications are presented to showcase the ability of UAV lidar to effectively quantify the many multiscale snow processes defining snowpack dynamics in mountain and prairie environments.

scholarly journals Using Unmanned Aerial Vehicles (UAV) for High-Resolution Reconstruction of Topography: The Structure from Motion Approach on Coastal Environments

2013 ◽  
Vol 5 (12) ◽  
pp. 6880-6898 ◽  
Author(s):  
Francesco Mancini ◽  
Marco Dubbini ◽  
Mario Gattelli ◽  
Francesco Stecchi ◽  
Stefano Fabbri ◽  
...  
Keyword(s):  
High Resolution ◽  
Unmanned Aerial Vehicles ◽  
Structure From Motion ◽  
Coastal Environments ◽  
Aerial Vehicles ◽  
High Resolution Reconstruction
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