PARENT SESSION

5H - Catchment area mgnt
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Vogt, K.¹, ¹

(WEP/215) Expanding the GREAT-ER Methodology in the UK. From Catchments to Regions.

Keller, Virginie¹, Fox, Kay², Pope, Linda³, Young, Andrew¹, Whelan, Mick⁴, ¹ CEH, Wallingford, Oxfordshire, UK² University of Sheffield, Sheffield, S. Yorkshire, UK³ The Environment Agency, Reading, Berkshire, UK⁴ Unilever, Sharnbrook, Bedfordshire, UK

ABSTRACT- GREAT-ER (Geography Referenced Regional Exposure Assessment Tool for European Rivers) is a GIS based model which predicts probability distributions of the concentration of so-called down-the-drain chemicals in surface waters. The approach combines information on the frequency distribution of river flow for individual reaches in a river network with the locations and load distributions of point-sources (principally sewage treatment plants). In so doing, it provides more realistic estimates of environmental exposure than cruder multi-media approaches and more meaningful regional averages. It has already been successfully applied to a number of catchments in several European countries (e.g. UK, Italy, Germany, Belgium, France and Spain). The environmental risk assessment committee of the European surfactant and detergent industries (ERASM) is currently co-funding a follow-on project (UK-GREAT-ER) with the Environment Agency of England and Wales (the EA). This project aims to greatly expand the area in which GREAT-ER may be applied, taking it from the catchment scale to whole regions. The relevant data for point sources, river flow statistics and observed water quality have been collated and quality-controlled for four EA regions (Northeast, Southwest, Northwest and Midlands) which constitute a large proportion of England. River flow statistics at ungauged sites are estimated using the LowFlows2000 model based on empirical relationships established between catchment characteristics and measured flow data. These data are exploited by GREAT-ER to simulate the behaviour of chemicals as they are transferred through the river network. The LowFlows2000 water quality extension software, which can be used to launch the GREAT-ER simulator, is being developed in parallel. This software is also being considered by the EA to aid strategic catchment planning and environmental decision making required by the new Water Framework Directive.

Key words: Exposure Assessment, GREAT-ER, Regional Scale, Model