Which term defines the fraction of total precipitation that does not get absorbed into the ground?

The term that defines the fraction of total precipitation that does not get absorbed into the ground is the runoff coefficient. This coefficient measures how much of the rainfall contributes to surface runoff rather than being absorbed into the soil.

Understanding the runoff coefficient is crucial for analyzing water movement within a watershed and can help in planning for drainage systems, flood risk management, and irrigation practices. It incorporates not only the properties of the surface (like vegetation, soil type, and topography) but also the intensity and duration of rainfall, indicating the efficiency with which precipitation turns into surface flow rather than infiltrating into the ground.

These factors contribute significantly to hydrological models and inform decisions related to landscape design and management, especially in urban settings where impervious surfaces play a substantial role in changing natural drainage patterns.