I am sure many people have been following the Basin Plan with interest, and in particular the issues associated with water recovery. I thought I might comment on how Alluvium is now involved in the implementation phase of this water recovery.
As part of the Basin Plan the Commonwealth set limits on the amount of water that can be taken from river and wetland systems, called Sustainable Diversion Limits
(SDLs). In many cases SDLs were already being exceeded, while at the same time there are landholder concerns about the amount of water available for the irrigation industry to continue to operate and develop.
To manage the problem, the Federal Government essentially has two options to recover water back into the system. The most cost-effective use of public money is to buy back irrigation licences from willing sellers. However this option is largely unpopular with rural communities, where the concern is that if too many licences are bought up and people move out of the region then the whole irrigation infrastructure becomes very expensive for the smaller number of users who remain.
The other option is to recover water through making the system more efficient. The term ‘Environmental Works and Measures’
describes the approach of upgrading infrastructure to deliver and manage water more efficiently.
Alluvium has just been awarded the job to undertake a feasibility assessment of the two highest priority sites in the Murray-Darling Basin in Queensland. One of these investigations is to find engineering solutions to better manage the water regulators in the Lower Balonne.
In the early 1970s a number of weirs were constructed to manage stock and domestic water supply in the Lower Balonne. This had the effect of impacting on flows into the Narran Lakes
, further downstream. Our challenge now is to find a solution to achieve a more efficient way to deliver the environmental flows required by the lakes, while managing the needs of stock and domestic users.
To do this we will take into consideration the flow dynamics of the Lower Balonne distributary system with respect to break-outs and effluent flow streams, current operating arrangements of weirs and other private in-stream storages. Bringing together a multidisciplinary team with ecology, river engineering, 2D modelling and economic modelling, we will hopefully come up with solution that improves the heath of the Narran Lakes and offsets the SDL to make more water available for the local irrigation community.
Aerial view of Narran Lakes in March 2008 (MDBC Annual Report)