Improving Distribution Efficiency
Former Delivery Losses
Historically delivery losses have been over 30% between dam and farm, resulting from seepage into the ground, leaks in the channels and structures, filling of channels which have degraded to much larger than design and end of system outflows. Contrary to often expected, evaporation causes the smallest loss because of the short residence time the water is actually in the channels.
Harvey Water understands that to retain its licensed allocation it must demonstrate that it can use water efficiently and productively for the benefit of the local and wider communities in comparison to competing uses. Since 1996 when Harvey Water took over the management and ownership of the business and its assets, $18 million of irrigators’ funds have been invested to improve the system. The major focus has always been on improving the delivery efficiency between the dams and the farms in order to reduce losses.
Channel Replacement Strategy
The Channel Replacement Strategy employs the very basic principle of infrastructure improvement to reduce water losses, by replacing open water delivery channels with pipelines. It is to estimated to eliminate 17.1 Gigalitres (GL) of water losses incurred during the delivery process by installing a network of HDPE (Heavy Duty PolyEthylene) pipes in lieu of the wasteful open channel distribution.
The recently completed Harvey Pipe Project is one component of this long term development work undertaken by Harvey Water. Stage 1 piped areas in Harvey South, Stage 2 in Uduc and Stage 3 in Harvey North and Logue Brook.
For the irrigators, the outcome is a pipe scheme delivering water at gravity driven static head pressure of about 70 metres. The system is capable of supporting surface irrigation with scheduling of delivery and importantly, also provide the ability for farmers to readily undertake on-farm improvements in water use efficiency.
Improvements in on-farm water use include moving away from reliance on surface irrigation and towards higher technology and more water use efficient systems such as sprinkler and trickle. This development in infrastructure facilitates the change from low value surface irrigated pasture production for dairy and beef production to high value horticultural enterprises.