Groundwater Chapter 9, Section 2

Groundwater Systems Groundwater Water that collects in the pores and empty spaces of soil and rocks. Estimated that 14% of freshwater is groundwater. 30x more than that contained in all lakes and rivers.

Groundwater Systems Permeability Permeable Impermeable Pores in rocks and soil are connected. Water can flow through the rock and soil. Impermeable Pores are few in number or not well connected. Groundwater cannot flow through the rock or soil.

Groundwater Systems Groundwater Movement Groundwater will sink into the Earth’s crust until it reaches an impermeable layer. At this point, the water begins to fill up the pores in the rock.

Groundwater Systems Groundwater Movement Zone of Saturation Area where all the pores are filled with water. Water Table The upper surface of the zone of saturation. Aquifer A permeable layer of rock that lets water flow freely.

Water Table Wells A well must extend into the zone of saturation to reach water. A pump brings water to the surface. If the water table drops below the depth of the well, the well will go dry. This can occur during droughts or if water is removed from the well at a quicker pace than it can be replaced. If the pore spaces in a larger area remain dry over an extended period of time, the land will sink.

Water Table Wells Artesian Wells A well in which water rises to the surface under natural pressure. Doesn’t need a pump. Aquifer for the well is located in between two sloping impermeable layers. Water enters the higher end of the aquifer and puts pressure on the water in the lower end of the aquifer. If a well is drilled in the lower end of the aquifer, the water will naturally move up the well.

Water Table Springs Found on hillsides or other areas where the water table meets a sloping surface, allowing ground water to flow onto the surface. Water is usually cool because of the insulating qualities of the rock and soil in which it was contained. If the water is heated by nearby magma, the water comes to the surface as a hot spring.

Water Table Geysers A hot spring that periodically erupts. How it works: Groundwater is heated to high temps causing it to expand. The expansion forces some of the water out of the ground which drops the pressure on the remaining water. The drop in pressure causes the remaining water to quickly boil and produce steam. The steam and any remaining water shoot out of the ground.

The Work of Groundwater Cave Formation Water mixes with carbon dioxide gas to form carbonic acid. Acidic groundwater moves through pores and cracks in limestone, dissolving the rock. Eventually a cave is formed.

The Work of Groundwater Stalactites and Stalagmites Formed by deposits of calcium carbonate that have been dissolved from limestone. Calcium carbonate is left behind in a cave when water evaporates. Stalactites Hang from ceilings Stalagmites Grow on the floor

The Work of Groundwater Sinkholes A depression that forms when the roof of a cave collapses or when material near the surface dissolves Form in areas with lots of rain and lots of limestone (like Florida and Kentucky)