Chapter 14 Groundwater

1. Chapter 14Groundwater

2. 14.1 Water in the Ground

3. Some rainfall becomes runoff and some enters the ground to be stored as groundwater. • One factor that affects the amount of water that enters the ground is the type of rock or soil. • Other factors include climate, topography, vegetation and land use.

4. Porosity • The amount of water soil or rock can hold depends on the space between the particles. • A soil with high porosity has more empty space between the grains. • Well sorted particles also have more space between them.

5. Permeability • How easily water passes through a material describes its permeability. • The larger the pore spaces and the further apart they are allows for high permeability. • Materials like sand allow water to pass easily. • However, fine grained clays have very low permeability.

6. The Water Table • When rain falls, it is absorbed by the ground in most places. • The area that it travels down through is called the zone of aeration. • Eventually it travels far enough down that it reaches the zone of saturation. • How far down this zone • occurs depends on • climate, rainfall, slope, • soil thickness, etc.

7. In humid climates, the saturated zone can be very close to the surface. • In desert climates, it may be hundreds of feet down.

8. Ordinary Wells & Springs • Long ago people knew they could just dig down to the water table to obtain clean water. • By digging a well, people could lower buckets or use pumps to bring this water up. • An impermeable rock ledge • on a hill can allow for a • natural spring to occur. • Here water can only travel • out the side of the hill.

9. Artesian Formations • Permeable layers of rock that store and carry groundwater to supply wells are called aquifers. • Sometimes an aquifer dips between two impermeable rock layers. • As water travels down between these layers, an opening will allow an artesian formation. Here great quantities of water will rise from up from the ground.

10. Hot Springs • Some ground water comes into contact with very hot underground rock. • Some of this very hot • water makes it to the • surface in the form of • a hot spring.

11. Old Faithful, Yellowstone Park Geysers • A geyser is a hot spring that intermittently shoots hot water and steam into the air. • Hundreds of feet below the surface, water can become very hot under pressure. When this pressure is released, a geyser forms.

12. Fumaroles • In some places, this ground water can be used as a geothermal energy source. • Fumaroles are steam vents where recent volcanic eruptions have occurred.

13. Questions1. _______ is the amount of water soil or rock can hold depends on the space between the particles.2. How easily water passes through a material describes its ___________.3. Permeable layers of rock that store and carry groundwater to supply wells are called _________.4. A _______ is a hot spring that intermittently shoots hot water and steam into the air. Porosity permeability aquifers geyser

14. 14.2 Conserving Groundwater

15. Water Budgets • A budget describes the income and use of something. • With water we have rain and snow fall. • The water can soak into the ground and be used by trees and plants. Excess water will runoff and end up in streams. • If trees and plants do not need as much water, like in the winter, the ground stores water in a process called recharge.

16. During recharge, the soil is storing water. If rain continues until the soil is saturated there will be a surplus. • Any time the water is used by trees and plants, we have usage. • If the need is greater than the rainfall, we will have a deficit.

17. Groundwater Conservation • In many places, humans are using groundwater faster than nature can replenish supplies. • In addition, pollution threatens groundwater as well.

18. This then lowers the water table. • Near coastlines, saltwater can then seep into fresh water aquifers contaminating them Overuse of Groundwater • When groundwater supplies are depleted, the water table drops.

19. Another problem of groundwater overuse is subsidence. • When too much groundwater is used, the ground becomes compacted to the point ground level drops.. In the San Joaquin Valley of California, water overuse has caused the ground to sink 9 meters

20. Groundwater Pollution • Groundwater is recharged by rainfall seeping down into the ground. • If there is any pollution present like oil from roads, fertilizers and even sewage it ends up underground. • Over the years all kinds of toxic waste has been absorbed into the soil. • Many people have had • to moved from their • homes due to care- • lessness in the past.

21. Questions1. A _______ describes the income and use of something.2. If trees and plants do not need as much water, like in the winter, the ground stores water in a process called___________.3. If the need is greater than the rainfall, we will have a _______.4. When too much groundwater is used, the ground becomes compacted to the point ground level drops, this is called ___________. budget recharge deficit subsidence

22. 14.3 Groundwater and Geology

23. Minerals in Groundwater • When water evaporates, it leaves deposits behind. Therefore, rainwater is pure. • When water seeps into the ground it takes all of the dissolved minerals like carbon dioxide with it. • Ground water that contains large amounts of ions from dissolved calcium from limestone is called • hardwater

24. If you bath in hard water, the ions cause the soap to form a scum. • Hard water in heaters leaves deposits behind called boiler scales. • Artesian water is usually • warmer and harder than • river water.

25. Mineral Deposits by Groundwater • When groundwater containing dissolved minerals evaporates, mineral deposits are left behind. • Geysers leave behind a white porous substance called geyserite. • Petrified wood is formed from mineral deposits dissolved in groundwater replacing tree cells. • Most importantly, ground water deposits cement sand grains together forming sedimentary rock.

26. Mineral Springs • A spring with a high concentration of mineral matter is called a mineral spring. • These springs can be the result of … -water passing through easily dissolved rock -water containing gasses that turn to acid -really hot water that dissolves minerals • Some mineral springs are safe and used at health resorts. Some are highly alkali and are poisonous.

27. Caverns • Limestone is a bedrock that dissolves easily. • Carbonic acid (rainwater mixed with CO2) dissolves limestone the most. • As this rainwater flows down into limestone cracks, the openings become more porous and soon caves form underground.

28. Karst Topography • Areas that are made of easy to dissolve rock like calcite and dolomite, develop sinkholes. • Sinkholes form when rock underground is dissolved away by rainwater and the overlying rock collapses in. • Rivers in these areas can run into sinkholes and travel underground for miles.

29. Many sinkholes are found in Kentucky, Tennessee, Alabama and Florida due to karst topography. • Over the years people have been hurt and structures damaged due to sinkholes.

30. Questions1. Ground water that contains large amounts of ions from dissolved calcium from limestone is called _____ water.2. Ground water deposits cement sand grains together forming ____________ rock. 3. A spring with a high concentration of mineral matter is called a ________ spring.4.As rainwater flows down into limestone cracks, the openings become more porous and soon ______ form underground. hard sedimentary mineral caves

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