The Environmental Reserve and its role in retaining the diversity of birds at the Thukela Estuary

Abstract

In 1998, a new Water Act was promulgated in South Africa. The basic premise of the Act is that a river and its associated estuary are recognised as having a legitimate right to water as a resource. These aquatic ecosystems are entitled to the quantity and quality of water that will allow them to maintain their basic ecological functions. This is the Environmental Reserve. It is considered that aquatic ecosystems must sustain these functions as they, in turn, will guarantee and prolong the sustainability of the resource. This paper briefly outlines the basic Environmental Reserve methodology and the processes that are followed to achieve sustainability of the resource, specifically pertaining to estuaries where a scenario based approach is used. The Reserve determination for the Thukela Estuary on the north-east coast of South Africa and data relating to its aquatic birds are used to illustrate how the process is undertaken. Birds are one of five key biotic components used in the Reserve determination methodology. These data are evaluated in conjunction with the impacts of various flow scenarios proposed for implementation in the Thukela System and the resulting scenario-based impacts are assessed. From this a flow scenario, which would allow the estuary to remain within the current class of ecological functioning and at the same time allow maximum abstraction from the system for other uses, can be determined.