Extension of the QUASAR River‐Water Quality Model to Unsteady Flow Conditions

Abstract

Abstract A modification of the well‐known water‐quality model ‘quality simulation along river systems’(QUASAR) is presented in order to extend its ability, so that it may be considered applicable under unsteady‐flow conditions. An aggregated dead‐zone travel‐time parameter, based on (a) the kinematic wave velocity (celerity) of the flow wave and (b) the behaviour of the solute within so‐called ‘dead zones’, has been incorporated into the existing model formulation. This extends the current continuously‐stirred tank reactor‐based model process to account for the behaviour of solute under unsteady‐flow conditions. The enhanced water‐quality model has been validated by application to the Colorado River.