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The Estuary Health Index: A standardised metric for use in estuary management and the determination of ecological water requirements
Expanded Title:The National Water Act of 1998 requires the implementation of 'Resource Directed Measures' (RDM) in order to make optimal use of our country’s water resources while minimising ecological damage. The main focus of RDM is the determination of the 'Reserve', which is the water quality and quantity required for the protection of basic human needs and aquatic systems. The latter component, or 'Ecological Reserve', is the quality and quantity of water required to maintain a desired level of structure and function, or quality, of a specific aquatic system (e.g. river reach, wetland, estuary). The desired quality of the water resource will be defined by its ‘Ecological Category’ which can be A, B, C or D on a health scale of A to F While scientists are allowed to make recommendations for this category the “Recommended Ecological Category” (REC), the final decision will be based on ecological, social and economic criteria in a participative process called the National Water Resource Classification System’s Classification Process (Dollar et al. 2010; gazetted in 2010). The Department of Water Affairs is responsible for the Classification of all significant water resources in the country, including estuaries, and these decisions will be re-evaluated at intervals. Although the Classification Process was gazetted only recently, the remaining steps were first developed in 1999, the Reserve determination methods were devised in 1999 (DWAF 1999) and have been in use since then, though having evolved over time following increased experience and understanding of the methods in practice. This method will continue to the part of the more formalised Classification Process. In the Reserve determination process for estuaries, the method involves (a) estimating the present health status of an estuary, (b) setting an REC on the basis of this and its importance using a simple set of rules, (c) setting an EC based on the ecological, social and economic criteria, (d) predicting how health changes under a range of flow scenarios, and then (e) finding the flow scenario that most closely matches the REC in order to define the ecological Reserve. The Estuary Health Index (EHI) is central to the Reserve determination method.
Date Published:01/02/2013
Document Type:Research Report
Document Subjects:Ecosystem - Biodiversity protection
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1930/1/12
ISBN No:978-1-4312-0433-4
Authors:Turpie J; Taljaard S; van Niekerk L; Adams J; Wooldridge T; Cyrus D; Clark B; Forbes N
Project Leader:Turpie J
Project No:K5/1930
Originator:WRC
Organizations:Anchor Environmental Consultants ; Consortium for Estuarine Research and Management (CERM)
Document Size:2 410 KB
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