Exam 3 geology review

What is GW and what is its place in the water cycle?

• water held underground in the soil or in pores and crevices in rock.

• Liquid water flows across land (runoff)

• into the ground (infiltration and percolation)

• through the ground (groundwater)

• Groundwater moves into plants (plant uptake) and evaporates from plants into the atmosphere (transpiration).

Gaining streams vs losing streams? What are they and why is it important to know this?

• a gaining stream generally gains water from the ground

• a losing stream a stream or river that loses water as it flows downstream.

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• streams provide drinking water and irrigation for crops, streams wash away waste and can provide electricity through hydropower.

How does ground water mover?

• downward and sideways underground through spaces between rocks.

• high elevations --> low elevation

• high pressure --> low pressure

What is a cone of depression?

• a gradual change, so the water table level around a well has a sort of cone shape.

• water flows down to lower points, the cone of depression could change the direction groundwater flows in

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Aquifer systems

• a water-bearing rock readily transmits water to wells and springs

• an unconfined aquifer is an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall.

• an confined aquifer is an aquifer below the land surface that is saturated with water.

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Artesian systems

• A groundwater condition formed by water-bearing rocks (aquifers) in which the water is confined above and below by impermeable beds.

• A flowing artesian system is If water reaches the ground surface under the natural pressure of the aquifer

• a non flowing artesian is an artesian well in which the pressure is sufficient to cause the water level to rise above the top of the artesian aquifer but not above the land surface

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What are some effects of too much ground water?

• the water table, below which the ground is saturated with water, can be lowered

• can cause wells to dry up, & is expensive

• drawdown is a term applied to the maximum lowering of the groundwater table caused by pumping or artesian flow

• Land subsidence occurs when large amounts of groundwater have been withdrawn from certain types of rocks, such as fine-grained sediments.

sinkholes vs. subsidence

• sinkholes are holes caving instantly that only happens with limestones

• Subsidence is the sinking or settling of the ground surface that happens slowly.

why are Ogallala aquifers important?

• The Ogallala Aquifer provides significantly more water for users than any other aquifer in the state

• The Trinity aquifer is one of the most extensive and highly used groundwater resources in Texas. Although its primary use is for municipalities, it is also used for irrigation, livestock, and other domestic purposes.

• The Ogallala aquifer has contaminants leaked into the aquifer.

• The trinity aquifer has Population growth and a limited supply of groundwater has put the Trinity Aquifer in danger of depletion

What is ground water and why is it important?

• the water found underground in the cracks and spaces in soil, sand and rock

• is a major contributor to flow in many streams and rivers and has a strong influence on river and wetland habitats for plants and animals.

• our largest water source. 2/3 is used for food

• Groundwater will move from high elevation to low elevation and high pressure to low pressure