On the relationship of transient storage and aggregated dead zone models of longitudinal solute transport in streams

The relationship between the distributed transient storage (TS) and lumped aggregate dead zone (ADZ) models of longitudinal solute transport in rivers and streams is examined by a parallel application to tracer data and throu gh an investigation of parameter relationships. Both models accurately desc ribe observed solute transport in a stream where the effects of storage or dead zones significantly affect longitudinal dispersion. A moment matching technique, based on theoretical temporal moments, is used to develop parame ter relationships. Tests using the previously calibrated parameters, in add ition to simulation experiments, show that the moment matching procedure al lows ADZ model parameters to be reliably derived from TS model parameters a nd vice versa. An investigation of these parameter relationships reveals an important difference between the effective solute transport velocity and t he average reach flow velocity in streams subject to transient storage or d ead zone processes. A number of practical uses for the derived relationship s are suggested, including the ability to utilize powerful methods of syste m identification in the estimation of TS model parameters.