4.1 Irrigation water supply system
The volume reported in the water accounting statements (390 ML) refers to the volume of water in the irrigation scheme's distribution pipe network at 30 June 2012.
The volume of water within the irrigation scheme increased during the 2011–12 year by 20 ML due to the extension of the Somers Road Pipeline in the Harvey Irrigation District.
The volume of water within the irrigation water supply system was calculated by summing the volume of each section of the system. The entire irrigation system is a network of pipes. Therefore, the total volume of water within the irrigation system is the sum of the volumes of each section of pipe within the system.
The volume of a section of pipe is the product of the length of the pipe section (km) and the cross sectional area of the pipe (m2).
Assumptions, limitations, caveats and approximations
It is assumed that all the pipes in the irrigation water supply system are at full capacity and have uniform diameter. Unless the pipe network is augmented or partly decommissioned, the volume of water in the irrigation supply system will always be reported as 390 ML (from the 2011–12 year onwards).
This value is estimated to be in the range of +/– 5–10%.