Browsing by Author "Farrow, Luke"

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    National-scale geodata describe widespread accelerated soil erosion
    (Elsevier, 2020-04-20) Benaud, Pia; Anderson, Karen; Evans, Martin; Farrow, Luke; Glendell, Miriam; James, Michael R.; Quine, Timothy Andrew; Quinton, John Norman; Rawlins, Barry G.; Rickson, R. Jane; Brazier, Richard E.
    Accelerated soil erosion can result in substantial declines in soil fertility and has devastating environmental impacts. Consequently, understanding if rates of soil erosion are acceptable is of local and global importance. Herein we use empirical soil erosion observations collated into an open access geodatabase to identify the extent to which existing data and methodological approaches can be used to develop an empirically-derived understanding of soil erosion in the UK (by way of an example). The findings indicate that whilst mean erosion rates in the UK are low, relative to the rest of Europe for example, 16% of observations on arable land were greater than the supposedly tolerable rate of 1 t ha−1 yr−1 and maximum erosion rates were as high as 91.7 t ha−1 yr−1. However, the analysis highlights a skew in existing studies towards locations with a known erosion likelihood and methods that are biased towards single erosion pathways, rather than an all-inclusive study of erosion rates and processes. Accordingly, we suggest that future soil erosion research and policy must address these issues if an accurate assessment of soil erosion rates at the national-scale are to be established. The interactive geodatabase published alongside this paper offers a platform for the simultaneous development of soil erosion research, formulation of effective policy and better protection of soil resources
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    Testing the utility of structure from motion photogrammetry reconstructions using small unmanned aerial vehicles and ground photography to estimate the extent of upland soil erosion
    (Wiley, 2017-03-08) Glendell, Miriam; McShane, Gareth; Farrow, Luke; James, Mike R.; Quinton, John Norman; Anderson, Karen; Evans, Martin; Benaud, Pia; Rawlins, Barry; Morgan, David; Jones, Lee; Kirkham, Matthew; DeBell, Leon; Quine, Timothy; Lark, Murray; Rickson, R. Jane; Brazier, Richard E.
    Quantifying the extent of soil erosion at a fine spatial resolution can be time consuming and costly; however, proximal remote sensing approaches to collect topographic data present an emerging alternative for quantifying soil volumes lost via erosion. Herein we compare terrestrial laser scanning (TLS), and both aerial (UAV) and ground-based (GP) SfM derived topography. We compare the cost-effectiveness and accuracy of both SfM techniques to TLS for erosion gully surveying in upland landscapes, treating TLS as a benchmark. Further, we quantify volumetric soil loss estimates from upland gullies using digital surface models derived by each technique and subtracted from an interpolated pre-erosion surface. Soil loss estimates from UAV and GP SfM reconstructions were comparable to those from TLS, whereby the slopes of the relationship between all three techniques were not significantly different from 1:1 line. Only for the TLS to GP comparison the intercept was significantly different from zero, showing that GP is more capable of measuring the volumes of very small erosion features. In terms of cost-effectiveness in data collection and processing time, both UAV and GP were comparable with the TLS on a per-site basis (13.4 and 8.2 person-hours versus 13.4 for TLS); however GP was less suitable for surveying larger areas (127 person-hours per ha-1 versus 4.5 for UAV and 3.9 for TLS). Annual repeat surveys using GP were capable of detecting mean vertical erosion change on peaty soils. These first published estimates of whole gully erosion rates (0.077 m a-1) suggest that combined erosion rates on gully floors and walls are around three times the value of previous estimates, which largely characterise wind and rainsplash erosion of gully walls.