Lake Eyre Basin Rivers 12 Development and other threats to the rivers There are considerable pressures on the world’s biodiversity and natural resources, primarily from direct and indirect effects of human development, including habitat loss and degradation, invasive species, overharvesting, pollution and climate change (Kingsford et al. 2009). The rivers of the Lake Eyre Basin and their dependent organisms, people and cycles are similarly affected by human pressures, although the degree of this impact varies considerably. The most serious threat is habitat loss and degradation through the potential large-scale diversion of water from the rivers and their wetlands (Kingsford et al. 2014). There is a long history of changing the flows of rivers in the Lake Eyre Basin. Aboriginal people formed small dams across claypans (Gibbs 2009). Chinese ‘gardeners’ in the 19th century first diverted water from the rivers’ waterholes to irrigate paw-paw, bananas and oranges (Silcock 2009). There was even a waterwheel built at Cullyamurra Waterhole, near Innamincka (Fig. 1.1) while sophisticated weirs were built on the Diamantina River near Winton in the 1880s to control water for local gardens (Silcock 2009 Fig. 1.7). After colonisation by Anglo-Europeans, most governments and communities in Australia began developing water resources on our rivers by building dams and diverting water, predominantly for irrigation. The aim was to improve the regularity and predictability of water (Gibbs 2009), which is – somewhat ironically – the antithesis of the behaviour of the rivers of the Lake Eyre Basin (Walker et al. 1997). In the 1930s, the Bradfield Scheme was the ‘grand plan’ for the Lake Eyre Basin, with the Thomson River to receive water diverted from coastal rivers such as the Tully River, engineered to ‘flow’ over the Great Dividing Range through tunnels, similar to the Snowy Mountains Hydroelectric Scheme (Gibbs 2009). In ensuing decades, sporadic small irrigation developments have occurred along the rivers of the Lake Eyre Basin, and continue to this day (see Chapter 20), but there has been no large-scale irrigation development (i.e. equivalent to that along the rivers of the Murray–Darling Basin (Kingsford 2000a)). Water is also diverted to supply the towns in the Lake Eyre Basin, sometimes using weirs to hold water back (e.g. the weir at Longreach on the Thomson River). Large-scale developments of rivers come at considerable environmental, cultural and economic cost. Around the world, the impacts of water resource developments, the building of dams, diversion of water and development on floodplains have caused widespread degradation of rivers (Lemly et al. 2000 Kingsford et al. 2006b Kingsford 2015 Kingsford et al. 2016). The impacts include loss of biodiversity, pressure on ecosystem services, damage to Aboriginal cultural sites and declining socio-economic viability. There is also increasing recognition that the environmental and cultural values of river basins also have real economic value (see Chapter 18). In Australia, there is no worse example of the size and scale of severe ecological degradation than the rivers and wetlands of the Murray–Darling Basin, where there is widespread death of floodplain eucalypts, including river red gums, other plants, declining invertebrates, waterbirds, frogs, native fish and even woodland birds and small mammals (Kingsford et al. 2015). Development of water resources has come at considerable economic cost, severely affecting the livelihoods of pastoralists (see Chapter 14). Some rectification of this problem, by returning some water to the environment, has cost the Australian taxpayer more than 12 billion dollars and considerable public angst.
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