The role of surface water drainage in environmental change: a case example of the Upper South East of South Australia; an historical review

The role of surface water drainage in environmental change in Australia is rarely appreciated. Drains can modify surface water hydrology, not only altering flow regimes but also rapidly dispersing contaminants and altering the natural hydrological balance of associated flora and fauna. Yet drainage continues to be considered a viable management strategy rather than as a cause of land degradation. The impact of surface water drainage in an inherently saline area of South Australia, the Upper South East, is investigated. Surface water drains were constructed by developers in an attempt to increase the area of land available and viable for agricultural land use. Drainage strategies altered the natural direction, magnitude and frequency of surface water flow. The Upper South East has experienced periods of both increased surface water and flooding, and surface water deficit, in the past one hundred years. The region now receives less surface water than under pre-European conditions, but local runoff is channelled into and through the wetlands more rapidly than before European settlement. Future management strategies are likely to continue this trend, to the detriment of remnant natural wetlands.