Development of a sediment delivery model for application in large river basins

Abstract

This paper presents an analysis of available data on suspended sediment concentrations in rivers within the Yorkshire region. It identifies the main control on the mean suspended sediment concentration across 62 medium-sized catchments (5–380 km2) to be that of land cover/use, with the percentage of cropped and suburban/urban land accounting for 71·5% of the variation between catchments. Twenty-two of the sites have associated flow gauging, and analysis of this reveals a strong flow dependence for catchments with a high percentage of arable land. In the case of urbanized catchments, there is considerable scatter owing to the influence of point source inputs: notably sewage effluent, combined sewer overflows, drainage from colliery waste and mine waters. This scatter is due not only to the inherent variability within these point sources, which is not flow related, but also to the variable degree of dilution by flow in the main stream. As a first-order approximation, a simple regression model, in which sediment concentration is a function of the daily mean flow and the percentage of cropped and suburban/urban land cover can be used to generate daily time-series of sediment concentration. This model has been applied within the LOIS catchment delivery model and performs well across a wide range of catchment types. Results are presented for four catchments representative of the Yorkshire region. Copyright © 1999 John Wiley & Sons, Ltd.