In irrigation, what does 'head' refer to?

In the context of irrigation, 'head' specifically refers to the height of water above a certain point, typically measured in feet or meters. This concept is crucial because it relates directly to gravitational potential energy and the ability of water to flow due to gravity. Higher head results in greater pressure, which can influence how water moves through the irrigation system, affecting the efficiency of the system and the distribution of water to crops.

The other options pertain to different aspects of irrigation. Flow rate of water refers to the volume of water that passes a specific point over a set time, but it does not define head. Width of the irrigation area describes the physical extent of the field being irrigated, which is unrelated to the concept of head. Lastly, pressure in the hose is influenced by head but is a distinct measurement, as it can also be affected by other factors such as friction loss and the diameter of the hose. Understanding head is fundamental for efficient irrigation design and management, making it a key concept in this field.