Developing a Practical and Robust Feedback Control System for Open Water Channels to Deliver the Correct Amount of Water to the Intended User at the Desired Time
The majority of irrigation districts in the U.S. and throughout the world deliver water to their users using open channels. Supplying water in this manner presents a number of complications that usually results in the loss of water. Many of these complications occur because of sediment accumulation and vegetation growing in the channel. These complications impede accurate and timely water deliveries.
To deliver the correct amount of water to the right place at the right time, water managers must determine when to start the water diversion and determine the travel time to deliver the water at the required time. The delay time makes this a difficult task because the delay time varies over the growing season due to the vegetative growth and sediment accumulation. It is very difficult to determine the time delay change and subsequently make an adjustment to delivery procedures.
In recent years, a number of irrigation districts have installed automation equipment to provide water deliveries in a timely manner. This equipment consists of water-level sensors, gate-position sensors, gate actuators, onsite computer control units and data communication radios or phones. These automation systems are normally programmed with routines that provide remote monitoring, data collection and remote movement of the water delivery gates and structures. The majority of software is simple and provides limited operation of these sites and subsequently limited water savings ability. This project has taken further steps and developed software that will operate these remote water control sites and provide timely water deliveries. The program was implemented on an actual canal reach. A recently developed open channel flow control method that is reported by Stringam and Wahl (2014) was used to develop this program.
This project also developed a prototype soil moisture sensor to help irrigators track crop water use and order accurate water deliveries in a timely manner. This prototype sensor has been programmed to communicate directly with the farmer’s cellphone to provide timely soil water information. The light-based sensor is proving to provide accurate measurements for the soils that we have tested thus far. Providing an accurate sensor to irrigation farmers will help them order water for irrigating more precisely. This will make the canal feedback control software more effective for district managers who work to deliver water to water users.
Technical Report 393
irrigation, open channels, sediment accumulation, water delivery, automation systems, water diversion