Using a novel tracing‐tracking framework to source fine‐grained sediment loss to watercourses at sub‐catchment scale

Abstract

Although traditional sediment tracing approaches provide valuable information for characterising key generic sediment sources, Catchment Officers working as part of the Catchment Sensitive Farming initiative frequently require more detailed evidence to permit improved targeting of mitigation. Accordingly, a novel framework combining conventional sediment source fingerprinting and a dual signature tracking method has recently been used to improve sediment source information for the River Glaven (~115 km 2 ) priority catchment in eastern England. Conventional geochemical tracing incorporating a number of recent refinements to the mass balance modelling, including the combined use of local and genetic algorithm optimisation, was used to provide information on the average median relative contributions (AE95% confidence limits) of generic sediment sources in three sub-catchments, categorised as grassland (1 AE 1%-12 AE 1%) or arable (25 AE 1%-46 AE 1%) surface soils, damaged road verges (2 AE 1%-50 AE 1%) and channel banks/subsurface sources (20 AE 1%-50 AE 1%) and to provide a framework for the spatial extrapolation of tracking data. Particle tracking using fluorescent-magnetic grains was used to provide preliminary sub-catchment scale information on sediment loss from key components of the primary arable topsoil and channel bank generic sources, characterised, respectively, as wheelings (18 AE 1%-33 AE 1%) or inter-wheelings (7 AE 1%-13 AE 1%) and poached (19 AE 1%-47 AE 1%) or fluvially eroded (1 AE 1%-3 AE 1%) channel margins. The insertion of high-strength magnets in watercourses ensured that the tracking component of the novel framework links sediment loss from labelled areas to river channels as opposed to providing information to edge-of-field only. Uncertainty and prior information on source contributions are explicitly recognised by the framework. This study represents the first in the UK to link wheeling sediment losses to river channels. The findings underpin the importance of compacted areas used for trafficking as sources of, and conduits for, sediment delivery in the lowland agricultural landscape of the UK. Copyright

Sources of fine sediment stored in agricultural lowland streams, Midwest, USA

“…The final set of optimum fingerprinting properties is dependent on the ability of the composite signature to improve source discrimination. Previous studies have also reported similar variability in the number and combination of fingerprinting properties used in the final set of optimum fingerprinting properties at a subwatershed scale (e.g., Collins et al, 2010Collins et al, , 2013aSmith and Blake, 2014). Increasing the number of source samples within a subwatershed can help to address this issue.…”

Evaluating the importance of surface soil contributions to reservoir sediment in alpine environments: a combined modelling and fingerprinting approach in the Posets-Maladeta Natural Park

“…Martinez-Carreras et al, 2010b;Smith and Blake, 2014;Collins et al, 2013), though, discrimination of the soil sources with the fingerprinting procedure was possible for the alpine Benasque catchment because of its distinctive soil characteristics.…”

Soil Erosion in Britain: Updating the Record

“…New methods of ascribing the source of fine-grained sediments from arable fields and river banks using fingerprinting approaches are now available and emphasise the importance of compacted areas such as wheelings [105].…”