Programmable Logic Control of Automated Surface Irrigation Systems for Improved Water Use Efficiency
* Can cost-effective, robust, and user-friendly automation systems be developed for surface irrigation systems using new technology, which will improve water use efficiency?
Need and Benefit
Despite urbanization, agriculture is still by far the major water user in the Lower Colorado Region with over 80 percent of the total water consumption. Within the agricultural sector, about 95 percent is surface irrigation methods, despite generous tax and financial incentives to convert to drip and sprinkler irrigation. Surface irrigation will continue to be by far the predominant method of irrigation into the foreseeable future.
In recent years, research and demonstration projects in Arizona and California co-sponsored by Reclamation`s Yuma Area Office (YAO) and the Universities of California and Arizona concerning surface irrigation management have been completed and are continuing at the present time. These demonstrations have shown that surface irrigation systems in the Lower Colorado valleys can be efficiently managed using improved methods of determining irrigation cut-off time. (Bali, Sanchez & Zerihun). Application of these improved methods would produce substantial water savings in the Lower Colorado Region.
Widespread application of these improved methods of surface irrigation management are constrained by factors inherent in the current "state-of-the-art" in surface irrigation. Proper decisions on when water should be cut off to a set often must be made based upon a determination of the extent of water advance across the field. In practical terms, this is very difficult to do at night or even in the daytime with tall, dense crops. Changes in irrigation sets must be made at inconvenient times. In practical terms, the farmer must make full use of his labor by assigning other tasks to the irrigator or having the irrigator work multiple irrigations at the same time, which results in fields being over-irrigated. It is increasingly difficult to train and retain irrigation labor. This is normally a minimum-wage and tedious job. Recent increases in the minimum wage in Arizona and California have made irrigation labor more expensive. Irrigation labor is from 30 percent to 50 percent of total irrigation cost. These factors which constrain efficient water use with surface irrigation can be mitigated by the adoption of some degree of automation.
Very little research has been or is being done in this area. The USDA-Agricultural Research Service did some automation work in the Wellton-Mohawk Valley in the late 1970s and early 1980s (Dedrick and Clemmens) but their systems were not widely adopted due to cost and reliability with the available technology.
Automation of surface irrigation bears taking another investigation. In the last two decades significant improvements in electronic automation equipment for pressurized irrigation and water system control have been made. The economics (e.g., labor and water costs) have changed.
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