Dryland rivers under new focus

While Australia has more than one million rivers, more than 70% are dryland rivers and flow for only part of the year – and typically these aren’t recognised as rivers in large-scale analyses.

In a dry country such as Australia, accurate understanding of streamflow generation processes in intermittent rivers is crucial to understand the health of our troubled river system, according to Flinders University hydrology researcher Dr Margaret Shanafield.

“I think especially given the low/no flows and fires this year, we need to understand how catchments produce flow,” says Dr Shanafield.

“Let’s talk about rivers that go dry. We must include non-perennial, temporary, intermittent or ephemeral flows in our conversations about Australia’s waterways.

“Nonperennial rivers are a major – and growing – part of the global river network. New research and science-based policies are needed to ensure the sustainability of these long-overlooked waterways.”

This argument is explored in the paper “What Triggers Streamflow for Intermittent Rivers and Ephemeral Streams in Low‐Gradient Catchments in Mediterranean Climates,” by Karina Gutiérrez‐Jurado, Daniel Partington, Okke Batelaan, Peter Cook and Margaret Shanafield, which has been published in Water Resources Research journal.

The dry bed of the Woodforde River in central Australia, seen here in January 2011. Photo: Dr Margaret Shanafield, Flinders University.

Dr Shanafield says an increasing number of scientific papers examining various landscape and hydrological features look at river width, length and flow on a global scale.

Much of the research work that has been done on non-perennial rivers has been focused on the ecology. Less is known about the hydrology (including streamflow generation and cessation mechanisms) and water balance (the relative roles of evaporation and infiltration) of these waterways.

“There is little overarching work to link all the case studies together into a broader understanding of river systems,” says Dr Shanafield. “We also don’t clearly understand how the flora, fauna, and hydrology fit together, and how humans impact these systems for the better and worse.

“For this to change in Australia, we need scientists and water managers to come together and discuss their knowledge within an interdisciplinary context.”

Networks of researchers from different fields in Europe and the US have started meeting to discuss commonalities and knowledge gaps about non-perennial rivers.

However, despite the much higher prevalence of these dryland systems in Australia, there is still no network in Australia devoted to understanding our wealth of dryland river systems – which extends far beyond the Murray Darling Basin.

Dr Shanafield says it is now crucial for non-perennial river study in Australia to change.

“It is now clear that flow regimes have changed in many of our rivers, and the consequences have been severe, highlighted by news reports about the drying of the Darling River in spring 2019,” she says.

“Improved research will be a key to avoiding the damage caused by similar events in the future.

“Australian researchers must come together across disciplines to discuss and begin addressing short-term and long-term data needs, knowledge gaps, and research directions to address Australia’s pressing need for better understanding and management of its unique waterways.”

 

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