State Water currently operates the Murrumbidgee River system, which supplies about 1900GL of irrigation water each year to the river community and supports the region’s annual production of around $1.9 billion in agricultural goods.
The recent decade-long drought changed community expectations of how water is managed in Australia’s most important food producing region.
While demand forecasting has improved through soil moisture meters, remote sensing, better crop planting information and more comprehensive weather forecasting, advances in system-wide delivery and measurement of water from dam to farm has lagged behind.
Current river operations rely heavily on the experience and judgement of the river operator and are based on simple water balance modelling concepts. These models do not take into account the complexities of the catchment flow processes or river flow dynamics.
Providing reliable water deliveries to customers located, in some cases, many weeks of travel time downstream of the dams is particularly challenging. Consequently dam releases often exceed actual demands, which lead to significant water loss. This is because, once released, water is removed from the basin due to much higher evaporation and evapotranspiration rates in the lower part of the river system compared to the headwaters.
Improving the process for the identification of unaccounted losses, and reducing operational surpluses requires modelling tools capable of reproducing the key physical behaviour of the catchment and the river system, which can then form the basis for optimal dam release and weir operation strategies.