Which term describes the water flow to rivers as a result of urban paving reducing percolation?

Which term describes the water flow to rivers as a result of urban paving reducing percolation?

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

Answer: (A)

Runoff is the water that flows over the land surface toward rivers after rainfall. When urban areas are paved with impermeable surfaces like concrete and asphalt, rain cannot infiltrate the soil, so percolation is reduced and more water becomes surface runoff that quickly drains into storm systems and rivers. This is different from infiltration (water soaking into the soil), evaporation (water turning into vapor from surfaces), or transpiration (water lost by plants).

Runoff is the water that flows over the land surface toward rivers after rainfall. When urban areas are paved with impermeable surfaces like concrete and asphalt, rain cannot infiltrate the soil, so percolation is reduced and more water becomes surface runoff that quickly drains into storm systems and rivers. This is different from infiltration (water soaking into the soil), evaporation (water turning into vapor from surfaces), or transpiration (water lost by plants).