Documenting catchment suspended sediment sources: problems, approaches and prospects

Abstract

Establishing catchment suspended sediment sources is fraught with difficulty. Data collection comprises indirect and direct approaches and an overview is provided. The indirect approach uses a range of techniques to measure or evaluate sediment mobilization. Yet, although recent technological advances in surveying, remote sensing and photogrammetry provide improved resolution of temporal and spatial patterns of catchment erosion, these procedures take no account of source -river connectivity and the uncertainties associated with sediment routing. It is therefore only possible to infer the provenance of suspended sediment loads on the exclusive basis of on-site erosion data for different portions of the upstream catchment unless supportive information on sediment delivery is readily available. In contrast, the direct approach attempts to link sediment sources and flux using alternative means and therefore avoids the need for complementary information. Sediment fingerprinting best represents the direct approach to sediment sourcing and there remains substantial scope for exploiting the potential of this technique. The spatial complexity of sediment mobilization and transfer at the catchment scale necessitates a distributed approach to modelling. Recent developments in computer power and programming techniques are proving useful in this respect, but assembling the input and validation data required by distributed models continues to pose problems and it is frequently difficult to apportion the relative contributions from individual sediment sources. General prospects for future developments are discussed.

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

“…when the transporting agent is more effective at carrying the sediment). The sequence of transport, deposition and remobilization has also been described as a sediment cascade (Collins and Walling, 2004;Fryirs, 2013;Harvey, 2002). In the following sections, the spatial and temporal dimensions of the sediment cascade are further discussed.…”

“…A range of empirical models are used to analyze and quantify SS loads and sources in rivers and evaluate the importance of different drivers (Bilotta et al, 2012;Collins and Walling, 2004;Gao, 2008). While individually these models are useful for expressing SS transport for the process and scale under question, they typically address specific parts of the sediment cascade and are relevant to particular timescales.…”

Rural land management impacts on catchment scale flood risk

“…The same principle can be applied to sediment source tracing, through a technique known as sediment fingerprinting (Collins et al, 1997;Collins and Walling, 2002;Collins and Walling, 2004). Source sediments are ascribed a source type e.g.…”

Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

“…Sediment tracing techniques provide a direct method of determining sediment provenance (for reviews, please see: Collins and Walling, 2004;Davis and Fox, 2009;Guzman et al, 2013;Haddadchi et al, 2013;Koiter et al, 2013). Sediment tracing research has demonstrated that large dams reduce downstream migration of contaminated sediments (Lepage et al, 2016), that decontamination reduces downstream radiocesium transfers (Evrard et al, in review), and that alluvial soils, and the rice paddies occupying them, contribute disproportionately more sediment downstream relative to their spatial extent in the Fukushima region (Lepage et al, 2016).…”