Water level sensors help Australian irrigation
Figure 1 The Murray-Darling Basin covers 14% of Australia. It is Australia’s most important environmental and agricultural asset.
Figure 2 The Hume weir at Albury during the Millennium drought. These conditions prompted massive public investment in irrigation automation.
Irrigation management is serious business in Australia especially within the Murray-Darling Basin, a 1,000,000 square kilometer watershed that is home to Australia’s most productive agricultural land. The basin’s 23 rivers have some of the lowest and most variable flows in the world. A massive system of dams, lakes and canals stores water from mountain snowmelt and seasonal rains and distributes it to farms and communities throughout the growing season.
The Murray-Darling watershed has been under pressure since the 1960s, but a series of environmental and economic crises in the 1990s created momentum for changing the way water resources were managed. In 1991, a 1,000-kilometer outbreak of blue-green algae on the Murray River became a vivid symbol of the environmental stress associated with reduced river flows. Reduced flows were threatening sensitive wetlands, protected species and salinity levels throughout the watershed. Water shortages threatened everyone, including farms, industry, municipalities and tourism.
Australia’s response was one of the most sweeping water management reforms ever enacted. The Murray-Darling Authority was created in 2007 to develop the first cross-border water resource management plan. In 2012 the Murray-Darling Basin Plan became law. Once implemented, the plan would return 2,750 gigaliters of surface water to the environment. An additional $1.7 billion was appropriated in 2012 to provide an additional 450 gigaliters to the environment. The total 3,200 gigaliters to be returned would be provided in two basic ways: (1) modernization and automation of irrigation infrastructure from one end of the watershed to the other and (2) government-authorized selective water rights purchases on behalf of the environment.
Figure 3: Murray Irrigation manages 3,000 km of surface irrigation channels along the upper reaches of the Murray river in New South Wales. (Click to enlarge)
Figure 4: Dethridge wheels measured water use by counting revolutions on mechanical counters that were read manually each month. They are being replaced by modern digital water meters.
Murray Irrigation, Australia’s largest privately owned irrigation company, manages irrigation along the upper reaches of the Murray River in southeastern New South Wales. Their system distributes water to more than 2,300 farms covering approximately 750,000 hectares through almost 3,000 kilometers of gravity-fed earthen channels. This highly productive agricultural region has had its share of drought crises. The most recent major drought, the “millennium drought” from 2005 to 2009, resulted in a 63% reduction in water deliveries to farms and devastated agricultural production.
Managing this decades-old irrigation system has been a complex undertaking. Farm customers requested seasonal allocation of water based on the weather, crop maturity, soil conditions and other factors. Water orders had to be placed up to seven days in advance to allow for coordination, but a lot can change in a farm field in seven days. Delivering water through a spider web of surface channels is a complex manual process. Water levels and releases in each channel had to be balanced so that each customer received their water allotment regardless of their location in the distribution system. Murray Irrigation had to balance the requests of 2,300 farms as well as the needs of industrial and municipal customers on a day-to-day basis all while staying within Murray’s allocation within the greater Murray-Darling Basin Plan.
Historically, the system was managed manually through a system of channel control gates and mechanical water meters. Irrigation staff would travel to channel control points and raise gates a certain height for a specified duration to release water to downstream channels. Dozens of people positioned throughout the 3,000 kilometers of channels would attempt to coordinate water levels so that each farm customer received their requested water allocation when they wanted it. Customer water usage was typically measured with mechanical meters that had to be visited periodically to monitor consumption. Large contingency releases of water were necessary to make sure that end-of-the-line customers received the water volume they were entitled to with sufficient flow to make consistent field irrigation possible. The system was labor intensive and imprecise, but it was cost effective as long as water was plentiful. With devastating droughts and routine water scarcity, a more efficient system is critical.
Figure 5: Modern bridge gate with remote power and communications. A ToughSonic REMOTE 14 ultrasonic sensor is mounted on top of the stilling tubes beside the gate.
In 2013, Murray Irrigation began their Private Irrigation Infrastructure Operators Program (PIIOP) with a goal to reduce water distribution losses over the almost 3,000 km channel length. Described as a “once-in-a-generation opportunity to modernize our irrigation infrastructure and supply system,” the $169.2 million PIIOP is intended “for the benefit of all our irrigation customers and to provide improved water efficiency and productivity for our customers’ farm businesses.” The project calls for upgrading more than 2,200 water meters and more than 1,300 regulatory channel structures and integrating those devices through an enhanced telemetry and SCADA system.
Senix ToughSonic REMOTE 14 ultrasonic sensors provide real-time water level measurements to guide autonomous and semi-autonomous channel control structures in this new system. More than 1,000 irrigation control points have been replaced since work began in 2013. In this next phase of the project approximately 1,200 more channel control points will be replaced with sensor-driven, automated gates using ToughSonic water level sensors.
Murray Irrigation is implementing two levels of system automation. In Standard Level of Service (SLOS) areas, irrigation control points are controlled remotely. ToughSonic ultrasonic sensors mounted near each gate provide water level measurement data to Murray’s SCADA system. Control center operators monitor channel levels and water orders and issue remote gate movement commands to release water based on known time and volume parameters. Accurate and responsive, this system allows farmers to change their water orders every 12 hours.
In High Level of Service (HLOS) areas, irrigation control points are automatically controlled based on established parameters. Irrigation customers submit water orders online and the irrigation management system issues gate manipulation commands. The system monitors water level data from the ultrasonic level sensors and other sensor inputs to determine the quantity of water delivered. HLOS systems allow irrigation customers to order water as frequently as four times per day if overall system flow allows.
In both service areas water is distributed with precision and without the need for large and potentially wasteful contingency releases. Farmers benefit from shorter lead times and more stable flows, allowing them to water crops more precisely, reduce overall water consumption and maintain healthy crop yields.
Figure 6: Senix ToughSonic REMOTE 14 is installed in irrigation automation systems around the world.
Senix modified the ToughSonic 14 sensor to reduce energy consumption and improve surge protection during lightning storms. Improvements made for Murray Irrigation were later incorporated into the recently released ToughSonic REMOTE sensor product line. “We also now offer REMOTE versions of our longer range ToughSonic 30 and ToughSonic 50 sensors for flood management customers, like those used in the Iowa Flood Warning System and the Philippines Tsunami Early Warning System,” says Doug Boehm, founder and President of Senix. “When we received the first order for modified ToughSonic 14 sensors from Murray Irrigation, we decided to formally introduce it as the first model of our ToughSonic REMOTE product line.”
Changing weather patterns combined with population growth are creating crippling droughts in many parts of the world. Australia is meeting these challenges with effective policy change and major investments in irrigation automation technology.
The more precious water supplies become, the more carefully they need to be managed. Murray Irrigation is implementing one of the most sophisticated irrigation distribution systems in the world with state-of-the-art sensors, gates and SCADA technology, all designed to reduce waste and improve customer service. Irrigation officials from around the world are visiting the Murray-Darling Basin to learn more about the future of irrigation policy and irrigation automation.
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