What defines groundwater?

Groundwater is defined as subsurface water that resides in saturated soils and geological formations. This water is found below the Earth's surface, filling the spaces within soil particles and rock formations. Groundwater plays a critical role in the hydrological cycle, serving as a significant source of water for wells, springs, and natural ecosystems. It is essential for maintaining the flow of rivers and lakes through baseflow, especially during dry periods.

The other choices do not accurately describe groundwater. Water found only in rivers and lakes constitutes surface water, whereas groundwater is not surface-based. Water that evaporates from soil pertains to the process of evaporation and does not refer to water that is located underground. Rainwater that drains away refers to precipitation that flows over the surface rather than infiltrating the ground to become part of the groundwater system. Therefore, the definition of groundwater as subsurface water in saturated soils is the most accurate representation of this important resource.