QUASAR Lite : Excel Version of the Instream Component of the QUASAR/INCA Water Flow and Water Quality Model

Versions of the QUASAR model (Whitehead et al, 1997) and the INCA model (Whitehead et al, 1998, 2011) have been set up for a range of water quality determinands and applied to many rivers such as the Lambourn, Kennet, Tamar, Tame, Tweed and Lugg (Wye). The EA required a simplified version of the instream component of the models so that alternative land use scenarios could be simultaneously together with the impacts of point source discharges from Sewage Treatment Works or industrial sources.

The new Excel version of the model utilises a differential equation solver that allows for the QUASAR/INCA instream mass balance equations to be solved. The model simulates Flow, Nitrate, Ammonia, Total Phosphorus, Soluble Reactive Phosphorus, Sediment, E.coli, Pesticides and Pathogens. The Excel version is simple to use and is set up to simulate up to 4 reaches in a multireach river simulation, using a daily time step over a year. Thus overall seasonal and monthly patterns of behaviour can be evaluated as well as short term dynamics. The figure below shows a typical daily simulation over 2011 for the River Dearne for nitrate at 4 reaches along the river system. The model also generates statistic summaries for environmental impact assessment.
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Daily Nitrate Simulation for River Dearne at 4 Reaches over 2011


Whitehead, P.G., Wilson, E.J. And Butterfield, D. (1998) A semi-distributed Integrated Nitrogen Model for Multiple source assessment in Catchments (INCA): Part I - Model Structure and Process Equations, Science of the Total Environment, 210/211 pp. 547-558.
Whitehead, P.G., Williams, R.J. And Lewis, D.R. Quality Simulation Along Rivers (QUASAR) (1997) Part 1: Model Theory and Development. Science of the Total Environment, 194/195. 447-456.
Whitehead, P G, L Jin, HM Baulch, DA Butterfield, SK Oni, PJ Dillon, MN Futter, AJ Wade, R North, EM O’Connor, HP Jarvie. (2011). Modelling phosphorus dynamics in multi-branch river systems: a study of the Black River, Lake Simcoe, Ontario, Canada. Science of the Total Environment 412-413:315-323.
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