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, Margaret Shanafield. 

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

“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. (https://doi.org/10.1029/2019WR025041).

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

AUSTRALIAN RIVERS 'UNRECOGNISED'

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

Much of the research work that has been done on non-perennial rivers has been focussed 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,” Dr Shanafield said. “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 said it was 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 said.

“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.”

www.flinders.edu.au

ends

SCIENTISTS fear Australian insect populations are on the brink of collapse and are calling for the public’s help to paint a better picture of the problem so they can develop solutions to help tackle the challenge.

David Yeates is director of the Australian National Insect Collection (ANIC) at Australia’s national science agency, CSIRO. Dr Yeates said researchers around the world widely acknowledge insect populations are in decline, but don’t have a true understanding of what is happening in Australia. \

“Insects are essential. They provide billions of dollars’ worth of ecological services to us each year, such as plant pollination, waste disposal and pest control,” Dr Yeates said. 

“While insect declines are no doubt occurring in Australia, the extent of the problem is unclear.  

“We have good data on declines in some iconic species such as the Bogong moth, green carpenter bee and Key’s matchstick grasshopper, however very few of our estimated 250,000 insect species are being monitored.” 

ANIC holds the world’s largest collection of Australian insects, which are used for research purposes, including into biosecurity, natural resource management and ecology, among others. 

Dr Yeates said if more Australians used citizen science apps like iNaturalist Australia, Wild Pollinator Count and Butterflies Australia then solutions could be targeted in problem areas.  
Earlier this year, a research review of existing insect surveys by the University of Sydney’s Institute of Agriculture revealed 40 percent of insect species are likely to be in catastrophic decline within a century.  

However, most of the studies were completed in western Europe and the US, with a select few from Australia to China and Brazil to South Africa. 
The collapse of insect populations in Europe appears also to be occurring in Australia, with entomologists across the country reporting lower than average populations across a number of species. 
“The worry is, if insect populations are in decline, so are the populations of larger animals such as birds and lizards who rely on them as food,” Dr Yeates said. 
“We know in alpine NSW, there’s been a collapse in Bogong moth populations – a staple food source for iconic mountain pygmy possums in spring, and this decline is resulting in the possums starving, but for most species these detailed interconnections are unknown.” 
Experts gathered in Brisbane recently to discuss insect declines as part of the Australian Entomological Society conference and are calling for help to better understand what is happening to our insects. 
“We really need long-term data sets that would provide a better picture of what is happening with our insects – where they are and in what numbers,” Dr Yeates said. 
“This is valuable information we need to better understand the insect biodiversity we have in Australia.” 

www.csiro.au

ends