Em4885 irrigation management practices to protect ground water

4 CHAPTER
IP 2.02.03 - Use Surge-Flow Techniques
Objective
Surge is usually used to improve down-row uniformity but may also reduce surface runoff.
Description
“Surge flow” is the practice of applying water to a furrow in pulses rather than with a
continuous flow. That is, water will be turned into the furrow for a time, then stopped.
After some time, water is then re-applied, then stopped again. The pulses continue until
the furrow has been completely wetted (water advances to the end of the furrow).
The pulses may or may not continue even after the full furrow becomes wet. The
actual number and length of pulses, as well as the water flow and total set time,
depend on the site-specific situation.
It is common for the initial pulsing flow rates to be greater than the final, steady flow.
In this manner, some applications of surge flow result in a concurrent cut-back flow system
(see IP 2.02.10). For example, one type of implementation includes using a specialized
“surge-valve” in conjunction with gated pipe. The surge-valve is usually a TEE-type valve
connected to the gated pipe extending to either side of the valve. During the irrigation, the
water supply will be directed to the gated pipe on one side or the other of the surge-valve,
depending on which furrows are being pulsed. The water supply is split between the gated
pipe on both sides of the surge-valve for continuous flow until the end of irrigation after the
furrows are completely wet. This gives an automatic 50% cutback in individual furrow
flows. (Note that the irrigator still has to make sure that the pipe outlets are flowing equal
amounts of water.)
Figure 4-13 is a schematic showing the distance of water advance at the end of each of
three surges. The surge valve is in the middle feeding water to gated pipe on either side.
Water is turned to first one side (Sets 1, 3, and 5), then the other (Sets 2, 4, and 6) during
the surging of the irrigation. A the end of the surges, about 2:00 A.M., the valve will turn
water to both sides until the end of the set.
Set 2 - 8 AM - 10 AM
Set 4 - 1 PM - 4 PM
Head of Field
Set 6 - 9 PM - 2 AM
Bottom of Field
FIGURE 4-13. Schematic of a surge irrigation showing water advance at the end of each of three surges
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Set 1 - 6 AM - 8 AM
Set 3 - 10 AM - 1 PM
Set 5 - 4 PM -9 PM