Surface water is any body of water above ground, including streams, rivers, lakes, wetlands, reservoirs, and creeks. The ocean, despite being saltwater, is also considered surface water. Surface water participates in the hydrologic cycle, or water cycle, which involves the movement of water to and from the Earth’s surface. Precipitation and water runoff feed bodies of surface water. Evaporation and seepage of water into the ground, on the other hand, cause water bodies to lose water. Water that seeps deep into the ground is called groundwater

Surface water and groundwater are reservoirs that can feed into each other. While surface water can seep underground to become groundwater, groundwater can resurface on land to replenish surface water. Springs are formed in these locations. 

There are three types of surface water: perennial, ephemeral, and man-made. Perennial, or permanent, surface water persists throughout the year and is replenished with groundwater when there is little precipitation. Ephemeral, or semi-permanent, surface water exists for only part of the year. Ephemeral surface water includes small creeks, lagoons, and water holes. Man-made surface water is found in artificial structures, such as dams and constructed wetlands.

Since surface water is more easily accessible than groundwater, it is relied on for many human uses. It is an important source of drinking water and is used for the irrigation of farmland. In 2015, almost 80 percent of all water used in the United States came from surface water. Wetlands with surface water are also important habitats for aquatic plants and wildlife. 

The planet’s surface water can be monitored using both surface measurements and satellite imagery. The flow rates of streams are measured by calculating the discharge—the amount of water moving down the stream per unit of time—at multiple points along the stream. Monitoring the flow rate of streams is important as it helps determine the impact of human activities and climate change on the availability of surface water. Keeping track of vegetation around bodies of surface water is also important. The removal of vegetation, either through natural means such as fires, or through deforestation, can have a negative impact on surface water. Loss of vegetation can lead to increased surface runoff and erosion, which in turn can increase the risk of flooding.  

 

Surface Water

Rivers are a major type of surface water. Surface water is a key component to the hydrologic cycle. 

Noun

gradual changes in all the interconnected weather elements on our planet.

dam
Noun

structure built across a river or other waterway to control the flow of water.

ephemeral
Adjective

short-lived or transitory.

Noun

act in which earth is worn away, often by water, wind, or ice.

Noun

process by which liquid water becomes water vapor.

freshwater
Adjective

having to do with a habitat or ecosystem of a lake, river, or spring.

Noun

water found in an aquifer.

hydrologic cycle
Noun

system of recycling liquid, gas, and solid water throughout a planet. Also called the water cycle.

Noun

watering land, usually for agriculture, by artificial means.

Noun

shallow body of water that may have an opening to a larger body of water, but is also protected from it by a sandbar or coral reef.

perennial
Adjective

continual, perpetual.

Noun

all forms in which water falls to Earth from the atmosphere.

reservoir
Noun

large, concentrated supply or reserve.

Noun

overflow of fluid from a farm or industrial factory.

spring
Noun

small flow of water flowing naturally from an underground water source.

vegetation
Noun

all the plant life of a specific place.

Noun

area of land covered by shallow water or saturated by water.