Groundwater Notes

Water Cycle vocab Evaporation: liquid to gas from bodies of water Transpiration: liquid to gas from plants Condensation: gas to liquid

98% of available freshwater is groundwater

Porosity vs. Permeability

Porosity vs. Permeability. Porosity is the volume of open spaces (pores) in rock or soil. Permeability is the measure of a material’s ability to transmit water. The larger the grain, the more permeable it is.

High vs. Low Porosity

Smaller grains = Low permeability ex: Clay, Silt Larger grains = High permeability ex: Sand, Gravel Permeability

Which column has the highest permeability?

Ground water Water that is found in the zone of saturation is called ground water.

Water Water seeps into the pores in rock or sediment (percolation) and collects as ground water in aquifers. Drinkable water is called potable water. When an aquifer is depleted, it can be replenished. This process is called recharge.

Zones of Aeration and Saturation

Cone of Depression

Drawdown

Pump Driven Wells

Subsidence When the Earth’s surface sinks due to the removal of ground water.

Salt Water Intrusion

Artesian Wells A pump-less well in which the water rises to the surface because of hydrostatic pressure.

Springs and Perched Water Tables

Springs A flow of groundwater that emerges naturally at the ground surface Springs that are warmer than the average air temperature are called hot springs.

Hot Springs & Geysers

Geysers

How Geysers Work For geyser to occur there must be heat, water and a plumbing system. A magma chamber provides the heat, which radiates into surrounding rock. Water from rain and snow works its way underground through gractures in the rock. As the water reaches hot rock it begins to rise back to the surface, passing through rhyolite, which is former colcanic ash or lava rich in silica. The hot water dissolves the silica and carries it upward to line rock crevices. This forms a constriction that holds in the mounting pressure, creating a geyser’s plumbing system. As superheated water nears the surface, it’s pressure drops and the water flashes into steam as a geyser.

Karst Topography A topography consisting of numerous sink holes.

Sinkholes / Cenotes / Swallet holes

Sinkholes Water dissolves limestone (sediment made from skeletons of marine organisms) and the chemical reaction produces carbonic acid which is highly corrosive.

Stalactites vs. Stalagmites