Potential effectiveness of wetland restoration on enhancing baseflow at the Mataura River catchment

This project assessed how modelled wetland restoration in the Mataura River catchment upstream of Gore influences catchment-scale baseflow dynamics, using SWAT+ coupled with gwflow software. Spatial and temporal variability of hydrological responses, including water balance and surface-water–groundwater interactions, were examined, with particular attention paid to baseflow sensitivity and downstream propagation of low-flow dynamics. The study provides insights into the scale-dependent hydrological benefits of wetland restoration and informs decision-making for catchment management and ecosystem services enhancement. Wetland restoration primarily enhances low flow conditions by increasing baseflow, with hydrological responses concentrated near restored areas. Localised restoration produces small, spatially limited baseflow increases, while distributed, basin wide restoration generates larger, more persistent, baseflow gains that extend downstream. The consistency between baseflow changes and spatial patterns of recharge, saturation excess flow and groundwater–wetland exchange confirms the model’s ability to represent key catchment processes. At higher order rivers (e.g. Mataura at Gore), baseflow increases may fall within measurement uncertainty. Spatial analyses of recharge and saturation excess runoff provide the mechanistic explanation for these outcomes. (auths)