What is surface runoff?

Surface runoff refers to the movement of water over the land when precipitation, such as rain or melted snow, exceeds the absorptive capacity of the soil. This occurs when the ground is saturated or when the intensity of the precipitation is too great for the soil to absorb the water quickly enough. As a result, the excess water flows across the surface, often collecting in streams, rivers, or other bodies of water. This natural process plays a crucial role in the hydrological cycle, as it returns water to larger water systems and can contribute to erosion and nutrient transport in the environment.

The other choices describe different aspects of the water cycle or water storage systems. Evaporation pertains to the transformation of water from its liquid state to vapor form, which does not involve the movement of water across surfaces. The process of water seeping through the ground describes infiltration, where water enters soil, becoming groundwater rather than flowing over land. Captured water in reservoirs specifically refers to managed water storage systems that hold water for various uses, which is distinct from the natural process of surface runoff. Therefore, the definition focusing on the movement of excess water across land surfaces is what accurately represents surface runoff.