PARENT SESSION

1L - Exposure Modelling
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Lammel, G.¹, ¹
Co-chair: Dachs, J.², ²

(WEP/89) Linking SWAT-2000 and Low-Flows2000 for diffuse source contaminant modelling in the Exe.

White, Sue¹, Beaudin, Isabelle¹, Worrall, Fred ², Hollis, John ¹, Hallett, Steve¹, Cobby, David¹, Whelan, Mick³, ¹ Cranfield University, Silsoe, Bedfordshire, UK² University of Durham, Durham, County Durham, UK³ Unilever, Sharnbrook, Bedfordshire, UK

ABSTRACT- The aim of the TERRACE (Terrestrial Runoff Modelling for Risk Assessment of Chemical Exposure) project is to adapt and test a simulation model for the evaluation of diffuse-source chemical runoff at the regional scale across Europe. The TERRACE model will be integrated within a GIS, providing estimates of diffuse runoff contamination for the point-source river pollution model, GREAT-ER. The selected model for TERRACE, SWAT-2000 (Neitsch et al., 2001), is a conceptual, semi-distributed model which assesses the impact of long-term management and agricultural practices on water supplies and diffuse source pollution. Conversely, GREAT-ER uses a steady state, stochastic approach to allow risk assessment of chemical fate in river systems. In keeping with the risk assessment objectives of the GREAT-ER system, the TERRACE model will provide stochastic distributions for predicted levels of contamination. The mechanistic and stochastic viewpoints will be combined via a Monte Carlo sampling framework. Within this framework, the sampling strategy must be such as to preserve cross-correlation between the various input variables. The predictions should be applicable to individual locations and should also be modifiable by scenarios of different land management or chemical properties. LowFlows-2000, which provides the hydrological background to GREAT-ER will be used to define the river system to be used with SWAT-2000 and as a source of data for calibration of flow duration curve. This paper will explain how the link between SWAT output and the stochastic requirements of GREAT-ER will be done using LowFlows-2000 for the Exe catchment. Neitsch, S.L., Arnold, J.G., Kiniry, J.R. and Williams, J.R., 2001. Soil and Water Assessment Tool Users Manual, Version 2000 . Grassland, Soil and Water Research Laboratory, USDA Agricultural Research Service, Temple, Texas.

Key words: risk assessment, diffuse pollution, SWAT-2000, catchment modelling