GED Science Practice 2025 – 400 Free Practice Questions to Pass the Exam

Runoff is the term used to describe surface water that flows over the land and eventually makes its way to oceans, rivers, and lakes without infiltrating into the underground water supply. This process occurs when precipitation, such as rain or melting snow, exceeds the ground's ability to absorb the water, causing it to flow along the surface.

Understanding runoff is important because it plays a key role in the water cycle, affecting water availability and quality in aquatic ecosystems. Additionally, runoff can lead to soil erosion and the transportation of pollutants into waterways, impacting both the environment and human activities reliant on clean water sources.

The other options relate to different concepts: relative humidity refers to the amount of moisture in the air compared to the maximum amount the air can hold, salinity measures the concentration of salts in water, and rust is a chemical compound formed through the oxidation of iron, unrelated to the movement of water.