A new version of the rainfall-runoff model TOPMODEL is described in which the assumption of a quasi-steady state saturated zone configuration is replaced by a kinematic wave routing of subsurface flow implemented in a way that allows the simulation of dynamically variable upslope contributing areas. The new version retains the idea of a distribution of hydrologically similar points in the catchment but allows more flexibility in the definition of hydrologically similarity. This allows the new version to retain much of the computational efficiency of the original model while still allowing results to be mapped back into the space of the catchment. A comparison is gives of the original and dynamic versions in an application to the Slapton Wood catchment, Devon, UK, within the GLUE methodology. The new version provides results that are a better fit to observed discharges, with improved prediction bounds, and patterns of predicted deficits storage that are qualitatively more consistent with understanding of the responses of this catchment.