1 The Lake Eyre Basin one of the world’s great desert river systems 9 sequential floods occur (Kingsford et al. 2014). Floods which cover most of the lake return about every eight years (Kotwicki and Isdale 1991). Small floods or ‘in between’ flows are also critical to ensuring that waterholes are replenished and retain water through long dry periods (Bunn et al. 2006a). Variation in flows and flooding occurs up and down the rivers, varying in time and area. No two floods are the same. Minor changes in the rivers can alter where the water goes. Boom and bust cycles drive much of the ecology of the rivers and wetlands, producing tremendous responses in biological productivity during floods, which then ‘shut down’ during the bust periods. This complex variability in timing and extent of river flows imposes its signature on the network of rivers and wetlands. These can be broadly grouped into five different habitat types: waterholes, the main and ephemeral channels, floodplains, freshwater lakes and salt lakes. There are also many small claypans, swamps and interdunal areas that are not necessarily connected to the rivers and fill from local rainfall. They are an important part of the ecology, often with high concentrations of frogs (Main and Bentley 1964 Kingsford et al. 2006a) and invertebrates, such as freshwater crabs (Austrothelphusa transversa) and tadpole shrimps (Triops australiensis). Artesian springs supplied by the Great Artesian Basin (Fig. 1.1), also independent of the main rivers, are extremely important wetlands, supporting communities of plants, invertebrates and fish often found nowhere in the world except in these isolated inland pools, described in Chapter 3. Fig. 1.5. The Georgina River catchment, including Eyre Creek, creates vast areas of Channel Country where water spreads out across the floodplain through a network of small channels (photo, R. T. Kingsford).
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