© 2012 John Wiley & Sons, Inc. All rights reserved. Chapter 11: Water On and Under the Ground...

© 2012 John Wiley & Sons, Inc. All rights reserved.

Chapter 11: Water On and Under the Ground

Victoria Falls, Zambezi River, southern Africa

Learning ObjectivesThe hydrologic cycle• Describe the hydrologic cycle and its main

pathways and reservoirs.

How water affects land• Contrast the properties and actions of

streams, channels, and lakes.

Water as a hazard and a resource• Explain how floods occur and why prevention

efforts sometimes make flooding worse.

Fresh water underground• Describe the water table and the movement,

storage, and depletion of groundwater.© 2012 John Wiley & Sons, Inc. All rights reserved.

The Hydrologic Cycle

Hydrology• The scientific study of water.

Evaporation• Water changes from a liquid into water.

Transpiration• Water taken up by plants passes into the

atmosphere.

Condensation• Water changes from a vapor into a liquid or

a solid.




Figure 11.1a The hydrologic cycle


Figure 11.2 Reservoirs in the hydrologic cycle



Figure 11.2a Salt water

Figure 11.2b Frozen

Figure 11.2c Underground

Figure 11.2d Surface and atmosphere



Figure 11.3 Living on the water’s edge, Mississippi River, St. Louis, MO


How Water Affects LandStreams and Channels

• Stream• A body of water

that flows downslope along a clearly defined natural passageway

Figure 11.4a Straight channel


Figure 11.4c Braided channel


•Channel• The clearly

defined passageway through which a stream flows:• Straight• Meandering• Braided


Figure 11.4b Meandering channel

•Gradient• The steepness of a

stream channel•Discharge

• The mount of water passing by a point on a channel’s bank during a unit of time

•Load• The suspended and

dissolved sediment carried by a stream

Figure 11.5 A river changes shape



• Floodplain• The relatively

flat valley floor adjacent to a stream channel,

• Inundated when the stream overflows its banks


Figure 11.6a Floodplain

How Water Affects LandStream Deposits

• Alluvium• Stream sediment• Unconsolidated

sediment • Recently

deposited (geologically speaking)

Figure 11.6b Alluvial fan, Badwater fan, Badwater, Death Valley



• Delta• Sedimentary

deposit, commonly triangular, that forms where a stream enters a standing body of water

Figure 11.6c Nile River delta



Figure 11.7 Disappearing coastline, Mississippi River delta



How Water Affects LandLarge-Scale Topography of Stream Systems

Figure 11.8 Mississippi River drainage basin


What a Geologist Sees—Drainage Basins

Drainage basin of Wadi Al Masilah, south Yemen


• Drainage basin• The total area from

which water flows into a stream

• Divide• A topographic high

that separates adjacent drainage basins

Figure 11.9 Continental drainage in the Americas


How Water Affects LandLarge-Scale Topography of Stream Systems

How Water Affects LandLakes

Lakes are standing bodies of water that have open surfaces, in direct contact with the atmosphere.

Figure 11.10 A dying river from eutrophication © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource

Floods• An event in which

a body of water overflows its banks

Flood prediction and prevention

• Flood-frequency curve

• Recurrence interval

• Channelization

Figure 11.11a Mississippi River flood



Figure 11.11b Mississippi River flood, May 2011



Hydrograph•Graph plotting discharge vs. time to record the flooding of a stream

Figure 11.12 A hydrograph or stream discharge



Figure 11.13 Coastal flooding



Figure 11.14 Predicting floods© 2012 John Wiley & Sons, Inc. All rights reserved.

Flood-frequency curve•Floods of different magnitudes are plotted on a graph for a given river.

Water as a Hazard and a ResourceSurface Water Resources

• Reliable water supply is critical to human survival and health, agriculture, and other economic activities.

• Nearly 250 million people are designated as water-scarce.


Water as a Hazard and a ResourceSurface Water Resources

Figure 11.15 Principal watersheds of the world


Case Study: Mono Lake

a. Calcium carbonate spires form under water

b. Water is now fed back into Mono lake

c. Probably just in time to save the California gull


Fresh Water Underground

•Groundwater• Subsurface

water contained in pore spaces in regolith and bedrock

•Water table• The top surface

of the saturated zone

Figure 11.16 Water under the ground



How groundwater moves•Porosity

• The percentage of the total volume of a body of rock or regolith that consists of open spaces (pores)

•Permeability• Measure of how easily a

solid allows fluids to pass through it

Figure 11.17 Porosity in rocks and sediment


Fresh Water UndergroundHow Groundwater Moves

•Percolation• Groundwater

seeps downward• Flows under the

influence of gravity

•Recharge• Replenishment of

groundwaterFigure 11.18 How groundwater flows


•Discharge• Subsurface water

leaves the saturated zone

• Becomes surface water

•Spring• Occurs where the

water table intersects the land surface

Figure 11.21a Spring in the Grand Canyon


Fresh Water UndergroundHow Groundwater Moves

• Aquifer• A body of rock or

regolith that is water saturated, porous, and permeable

• Aquiclude• A layer of

impermeable rock• Artesian well Figure 11.19 Aquifers, confined and unconfined


Fresh Water UndergroundWhere Groundwater Is Stored

Figure 11.20a Artesian water Figure 11.20b Frozen artesian well, New York


Fresh Water UndergroundWhere Groundwater Is Stored


Figure 11.22 Wells: year-round and seasonal



Figure 11.23 Subsidence



Figure 11.24 The forgotten oil spill


Freshwater UndergroundWhen Groundwater Dissolves Rock

•Karst topography•Sinkholes•Cave• Underground open

space• A cavern is a system

of connected caves

Figure 11.25 a & b Karst


Amazing Places: Lechuguilla Cave

a. A bush of aragonite

c. “Pool fingers”

b. Soda straws

d. Gypsum crystals


Critical Thinking

• List the many ways we depend on the availability of fresh water in our daily lives.

• Where does your community obtain its water supply (i.e., groundwater, surface source)? Is the quantity or the quality of the water threatened?

• What would happen to the sea level and the shoreline if great ice sheets built up on the land?


© 2012 John Wiley & Sons, Inc. All rights reserved. Chapter 11: Water On and Under the Ground...

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Transcript of © 2012 John Wiley & Sons, Inc. All rights reserved. Chapter 11: Water On and Under the Ground...