10.9: Summary

Surface irrigation includes the methods of furrow, border, and basin irrigation. It is the oldest form and most commonly used method of irrigation in the world. Water is usually delivered to surface irrigation sets through gated pipe, siphons, or gated inlets. Water flows over the land by gravitational force. The land must be graded to a uniform surface with slopes from 0 to 2 %.

With surface irrigation it is important to properly proportion any water losses so that the total of runoff and deep percolation is minimized. This is accomplished by choosing the appropriate irrigation frequency, inflow rate or stream size, and set time.

To control or reduce runoff losses, the irrigator can choose to either block the downstream end of the field, use cutback irrigation, or use runoff recovery. All methods have advantages and disadvantages.

Surge flow irrigation can be used to help reduce set times and reduce infiltration rates of the soil so that infiltration is more uniform within the field. Surge flow is accomplished with special valves that are equipped with a programmable controller to cycle the water as desired.

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