Following an evaluation of system performance, Oakdale Irrigation District (OID) embarked on a program to modernise their gravity distribution system. In particular, they aimed to reduce outfalls and improve service by reducing fluctuations in channel water levels. With stable water levels, OID would be able to provide more consistent flows at farm service points and channel offtakes supplying downstream districts.
OID identified two key channels where improved control would realise significant benefits:
• The 10 km Claribel channel, which has 17 pools and supplies water to 75 farm service points and four channel offtakes. It was a priority for OID to significantly reduce annual outfalls of more than two gigalitres, while ensuring that customer service was not adversely affected.
• The 14 km Cometa channel, which has 13 pools and a channel slope of up to 0.8%. This swift moving channel required frequent operator adjustment to supply water to 21 farm service points, seven channel offtakes and two separately managed downstream districts. It was difficult to meet required flow setpoints for downstream districts while maintaining stable water levels at all farm service points using traditional methods.
“Automating two laterals has allowed us to better manage our water and enhance service levels to farmers. Farmers have benefited from consistent flow rates, which the system is able to achieve by closely matching demand and supply.”
On both the channels, Rubicon implemented a Network Control Solution, which is one of a range of solutions built from TCC™ (Total Channel Control™) technology. This involved replacing 42 gates in 30 structures with FlumeGates™.
OID also automated six service points along the Claribel channel with SlipMeters™.
Key elements of the solution included a server running SCADAConnect™ and NeuroFlo™ software, the brains behind the control of the networked FlumeGates and SlipMeters. Communications were supplied using a Rubicon telemetry network.
Network Control automatically coordinates the regulators in the two channels so that water passed through them exactly matches measured outflow at all points downstream.
All regulators are in constant communication with other upstream and downstream regulators and with the server, sharing information about water levels and flows along the length of the channel in real time. This means that water level fluctuations are minimised, ensuring high flows and service levels to all farms along the channel.
Outfall reduction, water level control, service to irrigators and delivery of flow commitments at offtakes have all greatly improved since the implementation of the solution. Examples of performance pre- and post-implementation are shown below.
Since the implementation of Network Control on the Claribel channel, unintentional outfalls have been completely eliminated as shown below. Based on 2010 season outfall figures, this would result in an equivalent savings of more than two gigalitres of water. Also, more consistent flow through service points have enabled farmers to irrigate more efficiently.
Water levels stable and flow commitments met
The implementation of Network Control on the Cometa channel has seen significant improvements in both channel water level variation and the consistency of flow to seperately managed downstream districts. Below is a graph of upstream water level at the Hirschfeld headgate, which provides flow to one of the Cometa’s downstream districts. Under manual control, the water level varied significantly. Under Network Control, water level is tightly controlled which ensures consistent flows to all farm service points and channel offtakes.