A river in crisis: the lower River Murray, Australia

Abstract

The ecological communities of the River Murray and its floodplain wetlands and woodlands are adapted to a highly variable flow regime. Today, the Murray is intensively regulated for irrigation and other uses, and is a vital water resource in a dry region. Flow regulation and diversions increased rapidly in the latter half of the 20th Century, but government policies and resource management programmes in 1980-2000 failed to counter progressive deterioration of river and floodplain environments. From 2000-2010, flows in the river were depleted by severe drought, exacerbated by over-allocation of water resources. In the Lower Murray, South Australia, the water shortage intensified long-standing problems with lack of over-bank flows, salinization of soil and water, declines of native flora and fauna and increases of alien species. Other effects associated directly with low flows included river-bank slumping, exposure of acid sulphate soils, degradation of wetlands, and dredging at the river mouth. The water shortage also hindered environmental water allocations, intended to restore floodplain areas. Above-average rainfall in the latter half of 2010 brought some respite, but the underlying problems remain. Future prospects may improve with implementation of the Murray-Darling Basin Authority's Basin Plan after 2012. Nevertheless, the long-term damage from lack of over-bank flows, exacerbated by drought, the likelihood of more frequent low flows under global climate change, the inertia of past governance and entrenched resistance to reforms all present enormous challenges. Although 'flood pulses' are the natural driver in river-floodplain systems, flows in the Murray (other than major droughts and floods) are controlled mainly by government water-sharing policies. The debate over an appropriate balance between economics and the environment fundamentally is political, and scientists need to forge new partnerships with policy makers and managers to advise on environmental consequences, and to provide advice in a form accessible by the wider community. © 2012 John Wiley & Sons, Ltd.