Water Beneath the Surface Ch 6 Groundwater underground

Water Beneath the Surface Ch. 6

Groundwater: underground water that fills almost all the pores in rock and sediment • -makes up 90% of the Earth’s liquid freshwater

Porosity: refers to the percentage of open spaces in rock or sediment

Porosity: • Affected by: 1. sorting: amount of uniformity in size of particle in a rock or sediment -same size particles=large porosity -different size particles= small porosity • 2. way particles are packed together – packed loosely= high porosity - packed tightly= low porosity

Permeability: how freely water passes through open spaces in rock or sediment • -open spaces must be connected to be permeable !

Impermeable: rock or sediment that water can not flow through

Ground water flow depends on permeability of aquifer and gradient of its water table. • Gradient increase = velocity of ground water increase Gradient decrease = velocity of ground water decrease

II. Water Beneath the Surface • zone of saturation: layer of groundwater where all pores are full • aquifer: body of rock through which large amounts of water can flow and much water is stored • water table: upper surface of the zone of saturation

capillary fringe: where water is drawn up by capillary action from zone of saturation • zone of aeration: zone that lies between water table and surface (remains dry except during rainfall) • soil-water region: space around soil accumulates water

III. Wells & Springs • well: a hole that is dug below the water table and fills with groundwater • cone of depression: cone-shaped depression in water table around a well • artesian well: well in which water flows freely with no pumping necessary • cap rock: top layer of impermeable rock

• spring: a natural flow of groundwater to the Earth’s surface that is found where the ground dips below the water table • artesian spring: natural flow of water to the surface from an artesian formation

• hot spring: hot groundwater that rises to surface before cooling

• geysers: hot springs that erupt periodically

Observe an animation showing how geysers erupt.

• Conserving Groundwater: Sources of pollution – water dumps, underground storage tanks, agriculture and lawn fertilizers, pesticides, leaking sewage

• Conservation – monitor levels of water tables, discourage uses of excess water, recycle, purifying used water

Results of Weathering by Groundwater • hard water: water that contains large amounts of dissolved minerals – has metallic taste, soap won’t make suds, damages appliances that use water

• caverns: large cave with connecting chambers

Observe an animation of cave formation.

• sinkhole: depression formed when the roof of a cavern collapses

stalactite: cone-shaped calcite deposit suspended from the ceiling of a cavern

stalagmite: cone-shaped calcite deposit built up from the floor of a cavern