Hydrologic Cycle Components and Fluxes
The hydrologic cycle describes the continuous movement of water above, on, and below the surface of the Earth. This cycle is essential for sustaining life and shaping the environment. It involves the movement of water between surface water, such as streams, lakes, and wetlands, and ground water, which is water found beneath the Earth's surface in soil pore spaces and in the fractures of rock formations. Understanding the components and fluxes of the hydrologic cycle is crucial because it helps explain how water is distributed and managed across different landscapes. This knowledge is vital for addressing issues related to water supply, water quality, and the health of aquatic ecosystems. By studying the interactions between surface water and ground water, scientists and water managers can develop effective strategies to ensure the sustainable use of this precious resource.
Water moves between surface water (like streams and lakes) and groundwater (water beneath the surface). Key terms include the water table, which is the top of the saturated ground-water zone, and flow systems, which describe how water moves through the ground. Students should picture water moving in three main ways between streams and groundwater: streams gain water from groundwater, lose water to it, or do both in different areas.
This interaction affects water availability and quality, making it essential for managing resources and protecting ecosystems.
Key Points
- Precipitation is the source of virtually all freshwater in the hydrologic cycle, falling nearly everywhere but with highly variable distribution.
- Evaporation returns water to the atmosphere nearly everywhere, but its rates vary considerably according to climatic conditions.
- Transpiration directly from ground water can cause cones of depression similar to those caused by pumping wells, especially where the depth to the water table is small adjacent to surface-water bodies.
- Infiltrating precipitation passes rapidly through a thin unsaturated zone adjacent to the shoreline, which causes water-table mounds to form quickly adjacent to the surface water.
- Storage of water in streambanks, on flood plains, and in wetlands along streams reduces flooding downstream.
Terms
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Sources & licensing(4)
- Thomas C. Winter, Judson W. Harvey, O. Lehn Franke and William M. Alley, Ground Water and Surface Water: A Single Resource, U.S. Geological Survey Circular 1139 — pubs.usgs.gov/circ/circ1139/ (U.S. Government work (public domain, 17 U.S.C. 105))
- NOAA National Weather Service, JetStream — An Online School for Weather — www.noaa.gov/jetstream (U.S. Government work (public domain, 17 U.S.C. 105))
- Wikipedia contributors — en.wikipedia.org/wiki/Water_cycle (Creative Commons Attribution-ShareAlike 4.0)
- Wikipedia contributors — en.wikipedia.org/wiki/Water_balance (Creative Commons Attribution-ShareAlike 4.0)