Water flows on Cooper Creek in arid Australia determine 'boom' and 'bust' periods for waterbirds.

摘要

The effect of diverting water for irrigation from rivers was investigated at Cooper Creek, Australia. Data on waterbird distribution and abundance were collected during a boom period (1989/1990 flood) when Cooper Creek ran into Lake Eyre and overflowed into Strzelecki Creek to fill Lake Blanche. There were about 500 000 waterbirds in December 1990, making the area one of the most important for waterbirds in Australia: Lower Cooper (138 000), Lake Eyre (325 000), and Lake Blanche (40 000). Coloniesof Australian pelicans, cormorants, black swans, terns and silver gulls were established during this flood. Flow data and rainfall were used to estimate how often such a habitat in boom periods was created over a 100-year period, 1885-1995. It was estimated that the Lower Cooper (south of Lake Hope) received water approx. every 4.5 years, but the floods seldom reach Lake Eyre (8 out of 100 years). Cooper Creek overflowed into Strzelecki Creek when there were large floods (1906, 1950, 1974) or in 2 or more consecutive years of high flows (1916-1918, 1955-1956, 1989-1990). Lake Blanche filled 6 times and Lake Callabonna filled 4 times in 100 years. These wetlands depend predominantly on upstream flows of water. Potential irrigation developments in the catchment would divert water from the river and decrease the frequency and flooding of wetlands of the Lower Cooper. There would be fewer feeding areas and less breeding opportunities for waterbirds. Boom periods would be shorter and bust periods longer.