| Summary: | This study sought to assess the effect of floods and subsequent stream maturation on storage zones. Interannual physical surveys conducted at Pinal Creek, indicate that between major floods, the hyporheic storage zone decreases due to manganese (hydr)oxide precipitation and sediment concretion, while aquatic vegetation density increases. Comparison of transport and storage parameters, estimated by using the stream-tracer approach and the OTIS model, substantiated that total storage capacity increased in response to the recovery of aquatic vegetation. Between the summers of 1997 and 1998, increases were computed for the main channel cross-sectional area, A (0.400 to 0.693 m^2); the dispersion coefficient, D (1.23 to 2.71 m^2 s^-1); and the storage zone cross-sectional area, As (0.093 to 0.294 m^2); while the storage zone exchange coefficient, α (4.93 x 10^-4 to 2.55 x 10^-4 s^-1), and the mean main channel flow velocity, v (0.50 ms^-1 to 0.26 ms^-1) decreased. Although tracer-storage zone interactions may impact the value of estimated main channel parameters, the resulting lumped hydraulic characteristics reflect the temporal changes in storage zones.
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