Quality simulation along rivers (QUASAR): an application to the Yorkshire Ouse

The water quality model QUASAR (Quality Simulation Along Rivers) has been applied as part of the UK LOIS (Land Ocean Interaction study) project to simulate water quality in the Yorkshire Ouse. QUASAR has been calibrated using data obtained by the Yorkshire and Northumbria region of the Environment Agency (EA) in 1990, and validated using data collected for 1991 to 1993. A new methodology is outlined for estimating flows and water quality for the important ungauged tributaries in this river network. Results show that QUASAR can be used to simulate flow and water quality in a complex river systems such as the Yorkshire Ouse. The importance of accounting for point source and non-point source pollution is illustrated. Results of a basic sensitivity analysis of the model applied to one of the rivers of this system is also described.