Which term describes water that moves across the land surface (runoff)?

Which term describes water that moves across the land surface (runoff)?

• A. Groundwater Flow
• B. Interception
• C. Overland Flow
• D. Percolation

Answer: (C)

Overland flow describes water moving across the land surface as runoff. It happens when precipitation can’t infiltrate the soil quickly enough—due to high rainfall intensity, saturated soil, or impermeable surfaces—so the excess water travels downslope across the surface and into streams. This surface movement is distinct from groundwater flow, which occurs beneath the ground as water moves through pores in soil and rock, and from percolation, the downward movement of water into deeper soil layers. Interception is the water captured by vegetation on leaves and stems before it reaches the ground, which can lessen how much becomes surface runoff. Understanding this helps explain how storms translate into surface runoff and contribute to river discharge, and why factors like soil type, slope, and land cover shape the amount of water that runs over the surface.

Overland flow describes water moving across the land surface as runoff. It happens when precipitation can’t infiltrate the soil quickly enough—due to high rainfall intensity, saturated soil, or impermeable surfaces—so the excess water travels downslope across the surface and into streams. This surface movement is distinct from groundwater flow, which occurs beneath the ground as water moves through pores in soil and rock, and from percolation, the downward movement of water into deeper soil layers. Interception is the water captured by vegetation on leaves and stems before it reaches the ground, which can lessen how much becomes surface runoff. Understanding this helps explain how storms translate into surface runoff and contribute to river discharge, and why factors like soil type, slope, and land cover shape the amount of water that runs over the surface.