what is a lake?
inland surface waters, but not always fresh…. some bodies of water are permanent, semi permanent, and many artificial.
inland waters:
-non coastal
- aquatic-influenced environments located within land boundaries
surface waters:
any body of water above ground, including streams, rivers, lakes, wetlands, reservoirs, and creeks
what are the threats to freshwater resources including the plant and animal life there?
Water scarcity
Water quality
Over exploitation
Invasive species
Groundwater:
water found beneath Earth’s surface in sediments and rocks.
- Many cities rely on groundwater for most or all of their needs
- About half the water used in the United States comes from the ground
- lack visibility
Porosity:
the area of available air space within soil, sediments, or rocks
Permeability:
the ease with which water can flow through soil, sediments, or rocks
Infiltration:
the process in which water on the grounds surface is pulled downward by gravity and enters the soil.
Percolation:
the process in which water moves through soil through narrow, meandering channels.
- Infiltration is gravity driven
- Water movement through percolation is a result of water’s cohesive and adhesive property
Aquifer:
sediment or rock layer WITH pores that contain water
Aquiclude:
sediment or rock layer that LACKS pores and cannot contain water
groundwater zones - Zone of aeration:
layer of ground not permanently saturated
groundwater zones - water table:
the top surface of the aquifer’s zone of saturation.
- Water table fluctuates as a result of seasonal changes in precipitation, long-term climate change, and withdrawals of groundwater by people.
- Localized water table that lies above the regional water table
- Perched water tables sometimes create springs where hydraulic pressure pushes groundwater onto surface
groundwater zones - Zone of saturation:
layer of the ground usually saturated with water
groundwater zones - Capillary fringe:
the gradual transition between the zone of aeration and the zone of saturation
how does the groundwater move?
- Water table roughly parallels the height of ground surface.
- Contours of water table determine differences in hydraulic pressure (water pressure), and direction of water movement in the aquifer.
Potentiometric surface:
the elevation to which hydraulic pressure pushes water in pipes or wells.
- Water gushes from our faucets because homes lie below the potentiometric surface created by elevation of water supply.
wells lie above potentiometric surface, and water must be pumped out of them.
Water gushes out of some artesian wells.
