Browsing by Author "Glendell, Miriam"

Now showing 1 - 5 of 5
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    Assessing the source and delivery of organic carbon at a catchment scale using a combined sediment fingerprinting and carbon loss modelling approach
    (EGU: European Geophysical Union, 2022-05-27) Wiltshire, Catherine; Waine, Toby; Grabowski, Robert C.; Glendell, Miriam; Thornton, Barry; Addy, Steve; Meersmans, Jeroen
    Quantifying land use sources and understanding the dynamics of organic carbon (OC) in river catchments is essential to reduce both on-site and off-site impacts of soil OC erosion. The lake area of Loch Davan, located in Aberdeenshire, Scotland, has been significantly reduced over the last century due to sediment inputs and, in this study, we aimed to identify the primary source(s) and delivery of OC to the loch’s main feeder stream, Logie Burn and its major tributaries.
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    From field to stream: Tracing streambed organic carbon origins at a catchment scale
    (EGU: European Geophysical Union, 2021-04-30) Wiltshire, Katy; Glendell, Miriam; Waine, Toby; Grabowski, Robert C.; Thornton, Barry; Meersmans, Jeroen
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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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    Organic carbon across the terrestrial-to-aquatic continuum: Assessing source and delivery processess using a combined fingerprinting and carbon loss modelling approach.
    (Cranfield University, 2022-03) Wiltshire, Catherine M.; Waine, Toby W.; Meersmans, Jeroen; Grabowski, Robert C.; Glendell, Miriam
    Quantifying land use sources and understanding the dynamics of organic carbon (OC) in river catchments are essential to reduce both on-site and off-site impacts of soil OC (SOC) erosion. The aim of this research is to improve determination of the dominant terrestrial land-use sources of OC in freshwater sediment at a catchment scale and to assess the likely processes driving spatial and temporal changes in these sources. Four interlinked studies were conducted on two catchments to investigate specific objectives. First, OC fingerprinting and carbon loss modelling (a combination of “net” soil erosion and OC spatial distribution modelling) were carried out using existing OC and n-alkane biomarker data from Carminowe Creek, a mixed land use catchment in Cornwall, UK. This unique combination of two sediment origin techniques crucially identified that riparian woodland disconnected upslope eroded SOC and, concomitantly, provided an input of woodland-derived OC to the streams, giving an increased understanding of sediment and OC transport processes. Secondly, extensive new data from Loch Davan catchment, Aberdeenshire, was used to find the effect of novel combinations of n-alkane concentration ratios, n- alkane compound-specific stable isotopes (CSSI) and short-chain neutral lipid fatty acid (SC-NLFA) biomarkers on land use source discrimination using a Bayesian un-mixing model. In comparison to using only n-alkane ratios, a combination of n-alkane ratios and CSSI improved discrimination between arable and pasture land uses and using a combination of n-alkane ratios and SC-NLFA reduced error when discriminating four land uses (arable, pasture, forest and moorland). Thirdly, in an innovative approach, OC source proportions were identified, in both streambed and suspended sediment (SS), at a headwater sub-catchment and catchment scale. Different drivers of OC dynamics were detectable at the two different scales (sub-catchment and catchment scale), and different dominant land use sources were found in streambed and SS OC leading to improved identification of processes driving spatial and temporal OC dynamics. And finally, soil erosion “hotspots” (i.e. where there is high risk of soil degradation) can be identified by modelling catchment erosion using a variety of different erosion models. The utility of these soil erosion models in identifying hotspots, and guiding Best Management Practices (BMP), depends upon their accuracy and there is a need to assess model usefulness. Thus, a new method was developed and tested using streambed sediment land use -specific yields estimated using OC fingerprinting as a benchmark to determine which erosion model best identified the relative land use OC yields in streambed sediment. The new methods and findings from their application will improve determination of dominant terrestrial land-use sources of OC in freshwater sediment at a catchment scale, and support development of BMP to reduce impacts on land productivity and water quality due to changes in climate and human activity.
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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.