Thesis - Open Access
Master of Science (MS)
The total supply of water on the earth today is about the same as it was thousands of years ago. It is estimated that by the year 2020, 1,380 billion gallons of water will be used every day to satisfy the needs of 468 million people in the United States. Priorities will therefore have to be established to allocate the limited supply of water among the alternative users. One criterion, based on an economic analysis of the user, for making the allocation decision is presented by Reynolds. Unfortunately, agriculture has been awarded a rather low priority level as compared to municipal and domestic users. The largest single use of agricultural allocated water is for irrigation. It is estimated that by the year 2000, 150,000 million gallons of water per day will be used for irrigation purposes in the United States. It is estimated that 20 to 40% of the water applied by conventional means is lost due to runoff, evaporation, or deep percolation. One way to accomplish these goals is through the use of automation. Automation of surface irrigation systems, especially automation of cutback furrow irrigation systems, can optimize the use of water for irrigation. Even without automation, the cutback system employs two rates of flow which if properly timed can minimize the amount of runoff water. With automation the irrigation efficiency could be further improved. Garton states that not only is irrigation efficiency improved through automation, but the labor savings as a result of automation will pay the installation costs in less than the useful life of the system. Fishbach states that the three basic components of a well-designed automatic system are: (a) The Distribution System, (b) Electric Controls, and (c) The Telemetry System. The distribution system includes the water supply, the interconnecting valves and lines, and some type of outlet system to distribute the water on the land. The electric controls are responsible for adjusting and maintaining the rate of flow for ea.ch irrigation station, timing the irrigation of each station, and automatically sequencing the system after a predetermined time interval. The telemetry system measures and records the amount of moisture stored in the root zone of the field. The scope of this piper is to examine the part of the system which deals with electric controls. This thesis will investigate the use of automated flow control valves to program the application rates of water on the soil during an irrigation.
Library of Congress Subject Headings
Number of Pages
South Dakota State University
Kraft, Richard E., "Automatic Control of a Closed Conduit Cutback Irrigation System" (1972). Electronic Theses and Dissertations. 4796.