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.