A heavy rain produces runoff. Which reservoir does the water become a part of during this runoff process?

Runoff is the component of the water cycle where precipitation flows over the land surface rather than infiltrating into the ground. This overland flow collects in channels, such as streams and rivers, which then flow into larger bodies of water like lakes and oceans. These collective bodies of water on the Earth's crust are defined as surface water reservoirs. Therefore, during the runoff process, rainwater directly contributes to and becomes part of the surface water system.

A. Ground water: This reservoir is fed by infiltration, the process of water seeping into the soil, which is distinct from surface runoff.

B. Glaciers: Glaciers are reservoirs of frozen water; runoff is liquid water that typically flows to lower elevations, not into ice sheets.

C. Atmosphere: Water returns to the atmosphere via evaporation and transpiration, whereas runoff is the flow of water across the land.

1. U.S. Geological Survey (USGS). (2019). The Water Cycle: Surface Runoff. Water Science School. Retrieved from https://www.usgs.gov/special-topics/water-science-school/science/surface-runoff-and-water-cycle. In the main article, it states, "Surface runoff is precipitation runoff which travels over the soil surface to the nearest stream channel... Most of the water you see flowing in rivers comes from precipitation runoff".

2. Earle, S. (2019). Physical Geology (2nd ed.). BCcampus. Chapter 11.2, "The Hydrological Cycle," paragraph 4. The text describes runoff as the portion of precipitation that "flows over the land surface, eventually making its way to a stream, lake, or the ocean." This directly identifies streams, lakes, and oceans (surface water) as the destination for runoff.

3. Pidwirny, M. (2006). "The Hydrologic Cycle". Fundamentals of Physical Geography, 2nd Edition. University of British Columbia, Okanagan. Chapter 8(b), "The Hydrologic Cycle," section "Surface Runoff." This source defines runoff as water that "is collected and transported by a network of streams and rivers" to larger bodies of water.