Scientists continued to monitor rivers during the floods

Prof Watts leads the Edward/Kolety-Wakool Flow-MER (Monitoring, Evaluation and Research) Program funded by the Commonwealth Environmental Water Office.

“Large floods don’t occur very often, so we are keen to get out there to see what is happening,” Prof Watts said.

“It is crucial to continue to collect field data to assist water managers and so we can better understand what happens during floods.”

The Edward Kolety-Wakool system, a large anabranch of the Murray River, hasn’t experienced a flood event like this for decades.

This year, the floodwaters from Victoria’s Goulburn River flowed into the Murray River at the same time as floodwater arrived in the mid-Murray from Hume Dam.

This caused water to back up in the Murray River near Barmah, forcing water to flow north through the Millewa Forest and adjacent farmland into the EKW system.

For a period in November more than 60 per cent of Murray River water was flowing into the EKW system, and this travels downstream and will later flow back into the Murray River downstream of Tooleybuc.

The science team have continued to monitor water quality and fish populations throughout the flood.

Water quality monitoring, led by Dr Sha sha Liu (CSU), focusses on dissolved oxygen concentrations, water temperature, turbidity, and conductivity.

Data is collected both by handheld meters and by a network of loggers that continuously monitor water quality, day and night.

“Monitoring changes in dissolved oxygen are critical to inform water managers and the community,” Prof Watts said.

“One of the major environmental concerns about the floods is that it has resulted in hypoxic blackwater conditions (low oxygen, carbon rich water) that causes stress or death of fish and other aquatic animals.”

Dr Liu and her team also collect water samples to report on concentrations of carbon, nutrients and chlorophyl (algae).

During the flooding it has been difficult to access some of the water quality loggers.

“The problem we’ve had during the floods, is that a lot of our water loggers are well and truly under water and could not be retrieved to be maintained,” Prof Watts said.

“We will have to retrieve them later when the floodwaters recede.

“This means we will have some missing data, but we are continuing to monitor where we can, so we get enough data that is useful to understand what is going on across the system.”

Monitoring of fish spawning is led by Dr Nicole McCasker, and the fieldwork is undertaken fortnightly by John Trethewie (CSU) and staff from NSW DPI Fisheries.

The team is continuing to do the fortnightly fish monitoring, albeit at a reduced number and/or slightly changed sites because access to sites has been impacted by flooded roads.

Monitoring of riverbank and aquatic vegetation is undertaken by Sasha Healy (Murray-Darling Wetlands Working Group at a series of permanent transects.

However as the transects, on the riverbank and within the river channel, have been under water for some time they are unable to be monitored.

“It will be really interesting to see how the riverbanks have changed when the floods recede,” Prof Watts said.

“Members of the team have been working in the Edward Kolety-Wakool river system since 2010, and over those years we have seen it under a wide range of conditions ranging from drought through to floods. Our partnerships with local landholders, community organisations and agency staff are absolutely vital for the success of the monitoring and research.

“The results we collect from the fieldwork are used to guide real time management of Commonwealth environmental watering.

“The monitoring information is shared with managers from multiple agencies who have been meeting weekly during the flood to discuss and plan their response to the flood and have been releasing fact sheets to inform the community.

“The outcomes of the hard work that we have put in during the floods will also contribute to future adaptive management of environmental watering.”