Abstract Capture-zone analyses are widely used to facilitate protection of groundwater supplies. Even though frequently substantial, transients are commonly ignored in the capture-zone analyses assuming a steady-state flow. Furthermore, advection-only flow paths generally applied in capture-zone analyses might not provide an adequate representation of mean plume behaviour of potential contaminant transport, especially in transient conditions. Here we analyse the impact of the transients and dispersion in the groundwater flow and transport on the capture zone estimates for a series of synthetic cases. Conditions for performing transient advective–dispersive capture-zone analyses are defined. They depend predominantly on the magnitude of groundwater transport velocities at the spatial and temporal scales of interest.

Keywords capture zone; predictive uncertainty; transient analysis