Mulloon Rehydration Initiative update

The National Landcare Program-funded component of the Mulloon Rehydration Initiative (MRI) came to a crescendo last month with the Mulloon Rehydration Conference in Queanbeyan, NSW.  The two-day conference was an opportunity for Mulloon Institute to showcase its centrepiece project in all its catchment-scale glory to around 180 delegates from throughout Australia.

Eighteen years worth of monitoring data was presented, which clearly demonstrated that the condition of Mulloon catchment is improving. The most contentious issue has always whether the 60 or so instream structures would reduce water availability downstream. Analysis of 18 years worth of flow monitoring data shows there is no evidence of this being the case. On the contrary, based on the numbers, it is more likely that flow downstream of the works has increased, suggesting that water banking is actually occurring.

“Water banking” is a term first coined by Mulloon Institute’s Founder, Tony Coote. Water banking means that more water is held within the system (ponds, groundwater and soil) during high flow periods. This water is then released slowly when the system begins to dry out – say, an extended dry period or even a drought. Like we would deposit surplus money into our bank account during the good times and withdraw that money when times got a bit lean, in the same way, nature does so with water. This trickle flow during the dry times can keep natural systems alive and able to rebound quickly once the good times return.

All the biodiversity and productivity measures are positive:

  • Water quality has improved.

  • Riparian and instream plant assemblages and species richness have shown a significant improvement, providing complex habitat and moderation of high streamflows.

  • Aquatic Invertebrate numbers have exploded, representing major nutrient capture and export from the ponds back into the landscape.

  • Frog species richness in some cases has doubled.

  • The balance between native and introduced fish species appears to have flipped in favour of the natives.

  • Bird numbers have remained high. Over 80 species have been recorded including 12 rare and endangered species.

  • Rakali are returning and platypuses have been seen for the first time in decades.

  • A key productivity measure, Total Standing Dry Matter (TSDM) on the floodplain, has in some cases doubled since the instream works, possibly due to the increased frequency of over bank events.

The results are indeed exciting. The task ahead for the science team, along with the Science Advisory Committee, is to begin synthesizing the data into published reports and peer reviewed papers. There is also a bigger task of integrating all the data sets in such a way that we can categorically say landscape function of the Mulloon catchment has (statistically) significantly improved since the work first commenced.

See also:

Sharing the hydrological story at Mulloon.


MRI conference Presentations

Peter Hazell – Mulloon Institute
Download slides (PDF, 10.1 mb)

Phil Tickle – CIBO Labs
Download slides (PDF, 19.7 mb)

Dr Leah Moore – Mulloon Science Advisory Committee/Australian National University
Download slides (PDF, 3.9 mb).

Cass Moore