Answer:
Surface runoff refers to the water that flows over the land surface when the soil is saturated or unable to absorb all of the precipitation. Instead of infiltrating into the ground, the excess water runs off the surface and flows into nearby creeks, streams, rivers, or other bodies of water.
Surface runoff can have several effects on the Earth:
1. Erosion: As the runoff flows over the land, it can pick up soil particles and other sediments, leading to erosion. This erosion can cause the loss of fertile topsoil, damage to ecosystems, and sedimentation in water bodies.
2. Water Pollution: Surface runoff can carry pollutants such as fertilizers, pesticides, chemicals, and waste materials from urban areas into water bodies. This can result in water pollution, harming aquatic life and affecting water quality for human use.
3. Flooding: When there is excessive surface runoff, it can overwhelm the capacity of rivers, streams, and drainage systems, leading to flooding. Flooding can cause property damage, displacement of people, and disruption to ecosystems.
4. Altered Hydrological Cycle: Surface runoff affects the natural water cycle by altering the distribution and timing of water flow. It can impact groundwater recharge, water availability, and the overall balance of water resources in an area.
It is important to manage and mitigate surface runoff to minimize its negative impacts. This can be done through techniques such as constructing retention ponds, using permeable surfaces, implementing proper land use planning, and adopting erosion control measures.
Sources:
1. National Geographic Society - Runoff
2. Wikipedia - Surface runoff
3. U.S. Geological Survey - Surface Runoff and the Water Cycle