Review of Ecological Indicators and Assessment Programs

Abstract

Ephemeral rivers occur over much of Australia’s inland. However, much of the river health assessment to date has been conducted for rivers that have year-round flows or systems for which there is a significant amount of existing data. These tend to be in the catchments of eastern Australia and other catchments across Australia with intensive land use. Most of the rivers in the arid and semi-arid regions of Australia are ephemeral, and only carry significant flow during the wet season or following infrequent but intense rainfall events. It is not known which, if any, of the existing approaches to river health assessment can be used to accurately assess the health of ephemeral rivers and steams of smaller catchments, such as those around Adelaide in South Australia, or the larger ephemeral rivers of the Lake Eyre Basin. There are many definitions of ecological ‘health’ and a review of the concepts in relation to rivers can be found in Norris & Thoms (1999). "River health" is usually defined in terms of ecological integrity and is used to give a measure of the overall condition of a river ecosystem. The working definition of "river health" used by the National River Health Program (NRHP) is: 'The ability of the aquatic ecosystem to support and maintain key ecological processes and a community of organisms with a species composition, diversity, and functional organisation as comparable as possible to that of undisturbed habitats within the region' (Schofield & Davies 1996 after Karr & Dudley 1981:55-68).