What does the term 'flow' refer to in irrigation systems?

The term 'flow' in irrigation systems specifically refers to the movement of water through pipes, channels, or other mediums involved in the irrigation process. This movement is crucial for ensuring that water reaches the areas where it is needed for crops or landscape maintenance. Understanding flow allows irrigation technicians to design and manage systems effectively, ensuring that the right amount of water is delivered efficiently and that there are no blockages or leaks that might affect the system's performance.

The other options address different aspects that are not related to the direct concept of 'flow' in the context of irrigation. Pressure measurement deals with the force within the system rather than the movement of water itself. The rate of evaporation refers to how water is lost from the soil, which affects moisture levels but does not describe movement in the irrigation system. Lastly, the distribution of air pertains to aeration rather than water flow, which is a separate concern in irrigation management.