150. The Grain Size Characteristics of Overbank Deposits on the Flood Plains of British Lowland Rivers

Abstract

River flood plains are attracting increasing attention because of their wide-ranging environmental significance. In the UK, little is currently known regarding the grain size composition of the fine-grained overbank deposits that dominate most lowland river flood plains. This paper reports the findings of a study aimed at investigating the grain size composition of the overbank flood plain deposits associated with the flood plains of six rivers in southern Britain, embracing a range of catchment characteristics and hydrological conditions. More than 900 cores were collected from representative reaches along the flood plains of the six rivers and their grain size composition was determined. Analysis of the results obtained focuses on contrasts between the rivers, on within-reach and longitudinal variability in grain size composition and on the relationship between grain size composition and sedimentation rate.