Beschreibung: This data consists of a set of images recorded during aerial drone surveys on 2017/09/07 and 2018/09/25 using a 3DR IRIS drone (unpiloted quadcopter), equipped with a Ricoh GR4 camera (16.2 sensor, 28mm focal length, maximum aperture f2.8, shutter speed faster than 1/1000th sec). For each survey, two flights were undertaken: nadir imagery from 60 m above ground level (agl) and oblique (ca. 20° from nadir) images from 55 m agl, providing mean ground sampling distances ca. 16 mm. Also contained are the outputs of Structure from Motion photogrammetry (SfM) processing, which includes point clouds and derived raster products such as Digital Surface Models, Terrain Models, Canopy Heights Models, and Digital Elevation models of difference. SfM photogrammetric processing was carried out using Agisoft Metashape (v1.5) and constrained using 40 fixed ground control points, the locations and spatially accuracies of which are also provided here. Surveys were undertaken at Clyst William Cross County Wildlife site, England which has an area of 10 ha and is located on the River Tale, a 4th order stream (lat: 50.820, long: -3.313). These data were recorded to evaluate changes in the canopy height within a complex willow (Salix sp.) dominant riparian woodland, following the reintroduction of beaver (Castor fiber) in 2016. Further, these data were used to test a range of error propagation methods for elevation change detection, using drone-based SfM photogrammetry, and consider their application in vegetated systems. The code required to reproduce the derived SfM prducts can be found here: https://doi.org/10.5281/zenodo.5500199 and https://doi.org/10.5281/zenodo.5500203.

Beschreibung: Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2±0.1 m a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1 m d−1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m3 m−1 d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.

Beschreibung: Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2±0.1 m a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1 m d−1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m3 m−1 d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.

Beschreibung: Measurements were made of the hydraulic conductivity ( K ) of peat around a natural soil pipe in a blanket bog. This is the first investigation of decimetre-scale variability in both vertical K and horizontal K in blanket peats, which were found to be higher than indicated by previous research. This information suggests that it may be appropriate to reconsider (I) the spatial sampling strategies employed to investigate sub-surface flow in blanket peatlands, and (II) how field data are used to parameterise flow models. Critically, there was spatial structure in the heterogeneity, with a wedge of high- K peat directly above the pipe forming a hydrological conduit between near-surface peat and the perennially-flowing pipe. There was also significantly greater horizontal K parallel to the pipe's orientation compared with horizontal K perpendicular to the pipe. Determinations of the triaxial anisotropy of K , undertaken for the first time in peat soils, revealed substantial directional variations in K . The K around the pipe-peat interface was investigated; however, sample length dependency of K for peat samples precluded the investigation of a hypothesised low- K skin around the pipe.