Improving river efficiency in the murrumbidgee river, Australia

DHI has been awarded a major contract by State Water, New South Wales (NSW), Australia, for the delivery of a decision support system for the operation of the Murrumbidgee River.

Murrumbidgee means "big water" in the local aboriginal language. The river is one of Australia's longest at 1600km, and it is a major source of irrigation water to the Riverina region in NSW as well as an important source of water to the surrounding wetlands. "However, its management is a complicated task. The complex nature of the river system, coupled with the critical need to meet irrigation, environmental, and town water demands, often results in excess water being released and subsequently lost to the river system", explains Terry Van Kalken from DHI Australia.

A proof of concept of the CARM clearly showed significant water savings could be made

The river operator, the State Water Corporation, aims to increase the efficiency of river operations and to ensure that irrigators, environmental and other customers receive the right amount of water at the right location at the right time. Supported by DHI, they are implementing the Murrumbidgee Computer Aided River Management System (CARM). "The CARM 'engine' comprises a suite of MIKE by DHI simulation models, that accurately reproduce key catchment and river processes, including tributary inflows, river flow travel times, evaporation from open water and evapotranspiration from riparian vegetation", Terry adds.

"This project will establish the area as a leader in river management and efficient water use techniques. The upgrades and improvements will increase the accuracy with which this vital agricultural region receives its water, as well as enhance flood management capabilities," says Katrina Hodgkinson, NSW Minister for Primary Industries, in an accompanying press release.

The CARM integrates real time measurements with models to optimise river operations

In a proof of concept based on historical measurements, the CARM optimized solution has been shown to significantly reduce dam releases without compromising irrigation water security. Real water savings are realised through a reduction in river operating levels, which means less water is lost through evaporation and evapotranspiration.

The CARM will make full use of the existing and new monitoring data, including rainfall measurements and forecasts, river flows and extractions. The underlying hydraulic river simulation model will allow for a high level of control of the river, and allow State Water to accurately target both irrigation requirements and the watering of key habitats including the Lowbidgee Wetlands, one of the most important waterbird breeding sites in the region. When combined with a powerful optimization tool, the hydraulic model can minimise the impacts of dam releases during floods, and synchronise releases to "piggyback" on tributary inflows to inundate environmental assets and wetlands.

The system is being built around DHI's Solution Software (SOLSW) platform, which integrates the models and real time measurements with State Water's on-line data and control systems, and provides a range of fully customised user interfaces for the river operators.

The CARM project is part of the Murrumbidgee River Efficiency Project, supported by Water for Rivers, which will improve the monitoring of river flows and water use in the basin for the benefit of the environment. The executing agency is the State Water Corporation of NSW (www.statewater.com.au).

The State Water and DHI team at the CARM inception workshop, Dubbo, NSW

Yanco Weir on the Murrumbidgee River