What is surface runoff?

Surface runoff refers to the portion of water from rain, snowmelt, or irrigation that flows over the ground and eventually makes its way into rivers, lakes, and other bodies of surface water. This process occurs when the ground is saturated or impermeable, preventing water absorption, leading it to flow across the surface based on gravitational pull.

Understanding surface runoff is crucial in the context of environmental management because it significantly impacts water quality and quantity in aquatic ecosystems. When surface runoff collects pollutants such as fertilizers, pesticides, and sediments, it can lead to water pollution and eutrophication of water bodies. Furthermore, surface runoff plays a critical role in the hydrological cycle by aiding the redistribution of water within the landscape and contributing to the recharge of surface water bodies.

Other options describe different hydrological processes. The first option discusses evaporation, which refers to water changing from liquid to vapor. The second option concerns water infiltration and movement within soil, which is critical for groundwater recharge. The fourth option involves water absorbed by plants through their roots, which is key to maintaining plant health and ecosystem balance. Each of these processes is vital in their own right but does not define surface runoff.