CH 7 Water Quantity and Quality

hydrology

the fundamental science that deals with the occurrence, movement, and distribution of water on the planet

hydrologic cycle

the pathways for how water moves and is distributed above, on, and below the surface of the Earth

Pollution

the introduction of a substance to the environment at levels leading to a loss of a beneficial use of a water, air, or land resource or degradation of the health of humans, wildlife, or ecosystems.

point sources

stationary locations such as an effluent pipe

non-point sources (diffuse)

such as land runoff and the atmosphere

Clean Water Act

calls for the maintenance of fishable-swimmable conditions in U.S. waters

surface water

occurs as freshwater and seawater in streams, rivers, reservoirs, wetlands, bays, estuaries, and oceans. It also appears in solid form as snow or ice.

groundwater

when precipitation falls to the ground surface, some will run off to surface waters and some will infiltrate into the ground’s surface. it is the water that infiltrates the ground’s surface

baseflow

some groundwater remains close to the surface and quickly reappears above the surface, providing an important flow to surface water by recharging streams and rivers

aquifer

describes this underground soil or rock through which groundwater travels

saturated zone

describes the aquifer if is saturated with water. this zone from which groundwater is extracted to the surface

unsaturated zone

the zone where pores are filled with air and water. in this zone, fluctuations in the moisture content of the pores can occur daily and seasonally through intermittent or longer-term precipitation and other climate events

unconfined aquifers

water has infiltrated from the surface and saturated the subsurface material. if a well if placed in an unconfined aquifer, a pump will be required to life the water to the surface

confined aquifers

has a layer of rock or a confining layer of clay above and below it that are not very permeable to water. natural pressure in the confined layer can thus exist, and this pressure may be enough to push water in a well to the surface. however, not all confined aquifers produce this effect, so pumping may still be required to lift the water to the surface

watershed

the land that drains to a point of concern

runoff coefficients

tabulated in many sources. they can theoretically range from 0 to 1 and are influenced by the particular manner of land use, the type of soil or engineered cover, and the slope of the land. if the value is closer to 0 it implies that more rainfall if infiltrating into the subsurface, while if the value is closer to 1 it implies that the majority of rainfall is running off tot a local water source