Identifying hotspots for investment in ecological infrastructure within the uMngeni catchment, South Africa

Abstract

In recent times, there has been a growing recognition of the role which ecological infrastructure (EI) can play within the water resources management arena. However, practice has generally lagged conjecture regarding the integration of EI in the water resources management decision-making process. In this study, we aim to demonstrate how the state-of-the-art in ecosystem service modelling can be implemented to guide decision making with regards to investments in EI to improve the delivery of specific hydrological ecosystem services (HES) within the uMngeni catchment. For this purpose, the Resource Investment Optimization System (RIOS) and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models were applied to identify priority areas for investment and to evaluate the HES benefits that can potentially be achieved. Several global and local data sets were used to provide the requisite inputs to perform alternative land management scenario simulations. The results of these simulations demonstrated that potential investments in EI within the uMngeni catchment can lead to substantial reductions in sediment export (≈47%). Although, this may be accompanied by marginal decreases in the surface water yield (≈1.40%), there is a net benefit associated with reducing sediment export. Despite, these investigations being limited in their representation of HES due to inter alia the lack of localized data sets and inherent model limitations, the study successfully demonstrated how the RIOS and InVEST models can be collectively applied to guide decision-making regarding investments in EI.