Online water the order of the day in new irrigation scheme
The 2010 irrigation season has begun and NIWA is commissioning a new demand-driven irrigation control system. The system enables irrigators to order water online from Canterbury’s newest irrigation scheme.
The Acton Irrigation Scheme is in Canterbury, south of Rakaia township. It takes water from the Rakaia River at consented flow rates of up to three cubic metres per second (cumecs).
Delivering the right amount of water to the right place at the right time
Acton is the eighth major irrigation scheme NIWA has automated in just over a decade.
The Acton scheme is quite different from the others, however. The system now not only controls the water flow through irrigation races, but schedules and supplies irrigation water to order.
Each night users place orders for the water they require the next day. The scheme control system manages the reticulation and delivers the required amounts of water to the right place, at the right time, while ensuring that the total amount of water taken remains within Environment Canterbury’s consent limits.
The demand-based scheduling system allows for the time it takes for water to reach each user in a schedule. It may take several hours for water to reach those furthest from the intake. The scheduling system allows for this and admits water to the scheme early enough to allow for the travel time.
Eight flow stations deliver the water
The Acton Scheme currently has eight automatic water flow-control stations, and three buffer ponds.
A set of two automatic, hydraulically-operated control gates admits water from the Rakaia River. These gates limit and regulate the flow of water to the scheme intake where a second pair of controlled gates regulate flows into the scheme. A fish pass, located between these two double gate structures, enables fish to return to the river.
The three buffer ponds help regulate supply and demand when there’s more water flowing into the scheme than is being used, or when there is more water being used than going into it.
The water level at each buffer pond is automatically controlled. The ponds supply water to downstream races at times when it may not be possible to take enough water from the inlet to satisfy demand. Any water that exceeds scheduled user demands flows into a buffer pond, or ends up in one of the smaller holding ponds located at the ends of the scheme.
We monitor the water level at each buffer pond with a PumpPro compressed-air-bubbler water-level instrument. It measures water pressure and converts it to pond water depth.
Each of the eight control stations can operate autonomously, and regularly send data to the NIWA Neon irrigation server via a GPRS cellular connection. Authorised users can access real-time and historical data on the server via any Internet browser.
The scheme manager controls scheduling with specific setpoint management application software. It sends the daily schedules and setpoints to the NEON server. The server then sends the setpoint flow target to the Neon data logger at each remote station. These are normally updated every 15 minutes. The scheme manager can recalculate and update his scheduled setpoints at any time if necessary.
Text message alerts and alarms
The system sends text message alarms to nominated mobile phones if any data move outside the normal range. Nominated users, such as scheme racemen, can easily configure these alarm ranges, add appropriate messages, and query the current status of any of the nodes in the network.
Rooney Earthmoving, on behalf of Acton Irrigation Ltd, contracted NIWA to carry out the automatic control and demand scheduling of water. Other companies in the team were Environmental Consultancy Services Ltd (hydrology and consent monitoring), Alpine Hydraulics Ltd (gate hydraulics) and Bartlett Electrical (mains wiring).
Read more about other NIWA irrigation projects: