A palaeoenvironmental study of particle size‐specific connectivity—New insights and implications from the West Sussex Rother Catchment, United Kingdom

Abstract

Connectivity has become an important conceptual and practical framework for understanding and managing sediment transfers across hillslopes, between hillslopes and rivers, and between rivers and other compartments along the river corridor (e.g., reservoirs, channel substrate, and floodplain). Conventionally, connectivity focuses on the quantity of sediment transferred but here, we also consider the size of the finer sediment (typically particles <500 μm diameter). We examine the role of small rapidly silting reservoirs in the river Rother on storing sediment and disrupting downstream sediment transfers. Spatial and temporal changes in the particle size characteristics of sediment deposited in one of the ponds is explored in detail. Downstream of this pond, we collected sediment from the river on nine occasions over 17 months using two sampling methods at two locations; first, immediately downstream of the pond and a second ~700 m further downstream but upstream of the confluence with the Rother. Results showed a significant depletion in sand‐sized particles immediately downstream of the pond but the sand had been recovered from an in‐channel source before the river reached the downstream sampling point.

Monitoring soil erosion on agricultural land: results and implications for the Rother valley, West Sussex, UK

“…Collins et al (2009) and by publicity over a long period of time for the erosion problem (Evans, 2010). In the Rother valley, parallel work with the Sediment and Mitigation Options for the River Rother (SMART) project and the second phase SMART2 showed the importance of small ponds and reservoirs in detaining coarse sediment and allowing fine‐grained sediment to reach the river – with implications for pollution (Evans et al , 2017; Boardman et al , 2019; Evans, 2019; Foster et al , 2019). Burt (1994) comments that, ‘once established, other benefits accrue from monitoring – from discoveries made later, not from the original questions’.…”

Instream wood increases riverbed temperature variability in a lowland sandy stream

“…Experimental investigations within this study focused on the Hammer Stream, a third order tributary of the lowland Western Rother river, West Sussex, comprising ~25 km 2 of agricultural and forested land (Foster et al, 2019). The underlying Greensands and Mudstone geology result in the dominance of a fine sandy bed (D 50 = 0.28 mm), with peat and clay lenses throughout the river bed and floodplain to a depth of approximately 1–2 m (Shelley et al, 2017).…”

Sediment source fingerprinting: benchmarking recent outputs, remaining challenges and emerging themes

“…If it can be assumed that the varves are annual, the method can be used to help calibrate other dating methods (Fifield and Morgenstern 2009 ). The presence of coarse sedimentary layers relating to extreme precipitation events can also be used to help fine tune radiometric chronologies (Foster et al 2007 , 2019 ) whilst particle size analysis can help provide information on long-term palaeoflood records (Schillereff et al 2014 ) as particle size distributions are rarely modified by post-depositional diagenesis. More recently, Foucher et al ( 2020 ) have used high-resolution CT scanning to identify flood layers in sediment cores rather than stratigraphic or particle size data.…”