Modelling upland and instream erosion, sediment and phosphorus transport in a large catchment

This overview presents background information to place the subsequent papers by Beavis et al ., Dietrich et al . and Green et al . in the context of a unified approach. The modelling framework described here consists of two major components: an upland catchment model and an instream sediment transport model. The upland model simulates stream flow ( Q ), suspended sediment ( SS ) and associated phosphorus ( P ) using rainfall data, and is calibrated to daily stream flow time‐series under historical conditions. The instream model routes SS and attached P from the outlet of upland catchments to gauging points downstream. The instream transport model can infer sources (resuspension and bank erosion) and sinks (deposition) within a reach. Aerial photographs are used to assess the on‐site effects of climate and land cover/use on erosion and the drainage network. Changes in land cover/use and the effects on the drainage network are related to the parameters in the rainfall–runoff model so that associated effects on Q (and hence SS and P ) can be assessed. This modelling framework is prototyped on the Namoi Basin in northern New South Wales, Australia, and is described briefly herein. Copyright © 1999 John Wiley & Sons, Ltd.