The Pongola Floodplain, South Africa – Part 2: Holistic environmental flows assessment

Abstract

A holistic environmental flows (EFlows) assessment, undertaken as part of Ecological Reserve determination studies for selected surface water, groundwater, estuaries and wetlands in the Usuthu/Mhlatuze Water Management Area, South Africa, led to recommendations for modified releases from the Jozini Dam to support the socially, economically and ecologically important Pongola Floodplain situated downstream of the dam. The EFlows study analysed various permutations of flow releases from the dam based on the recommendations of pre-dam studies, and augmented by more recent observations, inputs from farmers and fishermen who live adjacent to the floodplain and discussion with the operators of Jozini Dam. The EFlows method used, DRIFT, allowed for the incorporation of detailed information, data and recommendations from a decades-old research project on the Pongola Floodplain that was undertaken prior to the construction of the Jozini Dam into a modern-day decision-making framework. This was used to assess the impact of a series of different flow releases on nature and society downstream of the dam. It was concluded that, within historic volumetric allocations to the floodplain, a release regime could be designed that considerably aided traditional fishing and grazing without necessarily prejudicing other uses, such as agriculture.