Sediment transmission and storage: theimplications for reconstructing landformdevelopment

摘要

The late Holocene (last 3000 years) development of the lower Ribblevalley (northwest England) displays evidencefor a complex esponse to a sediment recharge event forced by land-use change induced increases in erosion and sedimentdelivery. The deposition of fluvial sediments during the late Holocene was restricted to a series of eaches or depocentersseparated by zones with no sediment accumulation constrained by older glacial and fluvial terrain. Apparent reach-wide correlations of fluvial terraces break down under the scrutiny applied by comprehensive and extensive radiocarbon control. Bayesian testing of relative order models show that large-scale geomorphological changes, e.g. the progression from one terrace level to another, were time transgressive between different depocenters. The different histories of sediment delivery and storage are probably a function of local- and process-scale variations in these depocenters, and reflect (dis)connectivity relationships within a reach in propagating a basin-scale change (superslug) in the sediment regime. Disconnectivity in the depositional regime through a fluvial reach limits what we can reconstruct in terms of sediment budgets, but radiocarbon dating of multiple palaeochannels offers considerable potential for landform-based research to uncover rates of change within individual depocenters. Copyright 2009 John Wiley Sons, Ltd.