In irrigation design, what does the term head refer to?

• A. The vertical distance water is lifted into the pump.
• B. The slope of the land affecting pressure.
• C. The flow rate of water in gallons per minute.
• D. The pressure required to push water to the furthest point in the system.

Answer: (D)

Head is the pressure (or energy) the system must provide to move water from the source to the farthest point in the network, overcoming elevation differences and friction losses along the way. In irrigation design, this means the pump must deliver enough pressure to push water all the way to the last sprinkler, accounting for static lift, friction losses in pipes, and any velocity head. That’s why the best description is the pressure required to push water to the furthest point in the system.

The other ideas touch on related factors but aren’t the definition: lifting water into the pump describes suction-side lift, slope affects pressure but isn’t the term itself, and flow rate is about how much water moves, not the pressure needed to reach the farthest point.