What is cavitation in the context of water systems?

Cavitation in water systems refers to the formation of small vapor-filled bubbles in regions of low pressure, typically occurring on the trailing edge of an impeller in pumps. When the pressure decreases sufficiently, it leads to the formation of these tiny bubbles. As the impeller rotates and pressure conditions change, these bubbles can collapse or implode, creating shock waves and leading to potential damage to the impeller and other components of the hydraulic system. This phenomenon is critical in pump design and operation because it can cause erosion, reduce efficiency, and ultimately lead to system failure if not managed properly.

The other options do not accurately describe cavitation. Rapid rise of pressure does not characterize cavitation since it is essentially linked to the drop in pressure that facilitates bubble formation. Similarly, the leakage of pipes does not pertain to cavitation, which specifically occurs due to changes in pressure and flow conditions. A decrease in water velocity is not directly related, as cavitation is often a result of increased velocity leading to decreased pressure at critical points, fostering the conditions necessary for bubble formation.