Description of Irrigation Water Conservation Tools

Posted by Larry Heatherly

In an earlier blog, I outlined the MSPB’s SIP 2014 initiative. In that post, I listed several tools that can be used by irrigators to conserve water. Below is a brief description of those tools and how they will contribute to the conservation of water that is used for irrigation.

PHAUCET –-Pipe Hole And Universal Crown Evaluation Tool

The PHAUCET program was developed to improve distribution uniformity of irrigation water delivered from gated pipe.

The PHAUCET program is used to determine the size of holes to punch along the length of a polypipe irrigation set. This is based on pressure change along the tubing, pipe diameter, the different row lengths that will be encountered along an irrigation set, and the elevation changes that occur down the length of the pipe. The program is especially valuable for irregularly shaped fields.

Using this program may allow irrigation of a greater number of rows in a set, should allow irrigation water to reach the end of variable length rows more evenly, and can help reduce runoff and irrigation pumping time. A wide range of experiences has shown at least a 25% reduction in pumping time and applied water, and a reduction in irrigation costs.

Surge valve

With furrow irrigation, continuous flow from the entire line of irrigation pipe is the norm for applying water. However, applying water intermittently to an irrigation furrow results in water moving to the end of irrigated furrows more quickly than when applied by continuous flow. This can be accomplished by using a surge valve with an automatic controller, which automatically cycles irrigation water between the two sides of the valve. The net result is smaller applications of water with each irrigation as a result of reduced infiltration rates.

Zero grade

Mississippi’s crops are often irrigated by the flood method, which is the inundation of a field or paddy with water from one or a few sources vs. irrigation water that is delivered into individual furrows from multiple outlets in a line of pipe that is placed on the upper end of a field. This irrigation method results in irrigation water running to the low end of a field or paddy before filling the area contained within levees that separate individual paddies. This then results in more water on the lower than on the upper end of a paddy at the end of an irrigation cycle.

Zero grade is the term used to describe the process of making a field completely flat. This tool is used to remove slope within a field so that irrigation water is distributed at an even depth over the entire field during flood irrigation. Levees are not required within the irrigated area. The net result will be that less water is required to flood an individual paddy at each irrigation event.

Tailwater recovery

Tailwater recovery is a planned system to collect, contain, and transport water runoff from irrigated areas for reuse. The benefits from this process are 1) conservation of irrigation water by capturing and reusing the irrigation runoff water from a field, and 2) improvement of off-site water quality by preventing the downstream movement of sediments, nutrients, and chemicals that are suspended in the runoff water. Collection facilities may include ditches and on-farm water storage structures that are built for this purpose. Tailwater recovery systems may improve irrigation efficiencies from 25 to 30%.

Composed by Larry G. Heatherly, Jan. 2014, larryheatherly@bellsouth.net

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