Ecohydrology, Habitat Restoration, and Catchment Hydrology: Findings from a Modeling and Extreme Value Analysis Study

Techniques of distributed hydrological modelling, stakeholder land use mapping, and statistics were used to analyse the effects of rewetting and wetlands restoration at catchment level. The aim of this approach was to determine the catchment's response to the different types and geographical distributions of wetlands. Identification of potential sites for wetland restoration was based on soil properties and elevation data. Wetland restoration scenarios were then created that incorporated natural upstream-downstream catchment relationships. The four scenarios simulated were (a) Infiltration restoration, (b) Upstream headwater wetland restoration, (c) Downstream valley bottom wetlands restoration, and (d) Upstream valley bottom wetland restoration. The results point to river valley rewetting as having the effect of decreasing the paved overland component of stream flow, and increasing the saturated zone flow component. It promotes groundwater recharge. The catchment's actual evapotranspiration and root zone water responses were found to be varied, and were the consequence of a number of factors. This further proved the case that generalisation of wetland functions are of little use due to a high variability in local conditions, climatology and topography of the reported catchments.