Australian inland floodplain river systems
Large floodplain ecosystems are a characteristic feature of Australian inland river systems (Pickup, 1986; Thoms, 1995). Many are associated with extensive wetlands and terminal lake ecosystems and the ecological integrity of these lakes and wetlands is maintained by hydrological connections between the floodplain and the adjacent river channels. Although the abundance of wetlands in Australia is not well known, Blackley et al. (1996) list 744 in a directory of important Australian wetlands. Of these, 263 are associated with inland river systems. About 28,000 wetlands were identified across the Murray-Darling Basin, covering about six million hectares (Kingsford et al. 1999). These systems have a high biodiversity (Williams, 1988; Kingsford and Porter 1999) and play an important role as sites for feeding and breeding of waterbirds including migratory birds, fish and other animals. Whilst recognized as being environmentally and economically valuable, wetlands are also a threatened resource due to past and current land and water management practices.
The Condamine Balonne
The Lower Balonne floodplain wetland complex between St George (Qld) and Walgett (NSW) is a region that supports the largest number of wetlands >5 ha in size within the Murray Darling Basin. In excess of 3,400 wetlands have been identified, the majority of which are freshwater wetlands associated with floodplain areas (»53%). The Narran Ecosystem has been identified as one of nine significant refugia for biological diversity in semi-arid and arid New South Wales (Kingsford, 1999). This 10,000 ha ecosystem includes three major wetlands, Back Lake, Clear Lake and Narran Lake, a significant floodplain area and the main river channel of the Narran River itself. It represents approximately 15% of the land area of the Lower Balonne floodplain complex. Back and Clear Lake form part of the Narran Lakes Nature Reserve and are surrounded by an extensive floodplain lignum swamp.
The Narran Lakes System
The Narran Lakes Nature Reserve was listed as a Ramsar Wetland of International Importance in June 1999, eleven years after being gazetted as a Nature Reserve by the NSW National Parks and Wildlife Service. The Narran Lakes Nature Reserve is also listed on the Register of National Estate as a natural heritage site. The listing of the Narran Lakes Nature Reserve as a Ramsar site was in recognition of it being an excellent example of a relatively undisturbed terminal lake system for NSW. It is a significant site for waterbirds, both nationally and internationally; and because it provides habitat for some species that are recognised as being of conservation concern, either regionally, at the State-level or nationally. Together these attributes reflect the underlying ‘ecological character’ (incorporating the physical, chemical and biological attributes of an ecosystem and including the ideals of health and integrity) of the site, which the Ramsar Convention obliges Australia to protect. Similarly, national legislation (Environment Protection and Biodiversity Conservation Act) is committed to protection of such sites from threats. In addition, the site offers important habitat for several species listed under Australia’s bilateral agreements with the Governments of Japan (JAMBA) and China (CAMBA) for the conservation of migratory birds.
The Narran Ecosystem
The Narran floodplain wetland complex is a terminal system of the Narran River in the Condamine-Balonne Catchment River. The ecosystem of the Narran floodplain wetland complex consists of four distinct water bodies or lakes; Clear Lake, Back Lake and Long Arm in the north and Narran Lake in the south; a large flood-plain area throughout and a complex network of river channels that dissect the floodplain.
Associated with these physical features are a diverse array of different vegetation types, including trees, lignum, shrubs and grasses. The Narran Ecosystem Project team is evaluating some of the ecosystem responses of the Narran Ecosystem when flow varies and have sufficiently detailed information to form conceptual models of them.
website last updated 18th September 2007