Which process moves surface water into the soil, contributing to groundwater?

• A. Infiltration
• B. Runoff
• C. Transpiration
• D. Evaporation

Answer: (A)

Infiltration is the downward movement of surface water into the soil, where it percolates through pore spaces and can reach the water table to recharge groundwater. This process is how water moves from the surface into the subsurface, forming the start of groundwater replenishment. It differs from runoff, which is water that flows over the surface rather than soaking in; from transpiration, where plants release water from their leaves; and from evaporation, which is water turning into vapor from surfaces. Factors like soil texture, soil structure, moisture level, vegetation cover, and land use (such as impervious urban surfaces) influence how quickly or whether infiltration occurs. Where infiltration happens, groundwater recharge follows as water continues to move downward beyond the root zone.