What is surface runoff?

Surface runoff refers to the water that flows over the ground surface when precipitation or melting snow exceeds the ability of the soil to absorb it, known as infiltration. When the ground is saturated or impermeable surfaces like asphalt or concrete are present, excess water cannot enter the soil, leading to runoff. This can contribute to the movement of water into rivers, lakes, and streams, potentially causing erosion and transporting sediments.

The process is crucial for understanding hydrology, particularly in the context of water cycle dynamics and its impact on ecosystems and human activities. Surface runoff can play a significant role in flooding events, soil erosion, and the distribution of nutrients in water bodies. Recognizing it as the flow of water over land highlights its importance in surface water management and conservation efforts.