© 2012 John Wiley & Sons, Inc. All rights reserved. Chapter 11: Water On and Under the Ground Victoria Falls, Zambezi River, southern Africa

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

The Hydrologic Cycle Figure 11.1a The hydrologic cycle

The Hydrologic Cycle Figure 11.2 Reservoirs in the hydrologic cycle © 2012 John Wiley & Sons, Inc. All rights reserved.

The Hydrologic Cycle Figure 11.2a Salt water Figure 11.2b Frozen Figure 11.2c Underground Figure 11.2d Surface and atmosphere © 2012 John Wiley & Sons, Inc. All rights reserved.

The Hydrologic Cycle Figure 11.3 Living on the water’s edge, Mississippi River, St. Louis, MO © 2012 John Wiley & Sons, Inc. All rights reserved.

How Water Affects Land Streams and Channels Stream A body of water that flows downslope along a clearly defined natural passageway Figure 11.4a Straight channel © 2012 John Wiley & Sons, Inc. All rights reserved.

Figure 11.4c Braided channel © 2012 John Wiley & Sons, Inc. All rights reserved. Channel The clearly defined passageway through which a stream flows: Straight Meandering Braided How Water Affects Land Streams and Channels 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 © 2012 John Wiley & Sons, Inc. All rights reserved. How Water Affects Land Streams and Channels

Floodplain The relatively flat valley floor adjacent to a stream channel, Inundated when the stream overflows its banks © 2012 John Wiley & Sons, Inc. All rights reserved. Figure 11.6a Floodplain How Water Affects Land Stream Deposits

Alluvium Stream sediment Unconsolidated sediment Recently deposited (geologically speaking) Figure 11.6b Alluvial fan, Badwater fan, Badwater, Death Valley © 2012 John Wiley & Sons, Inc. All rights reserved. How Water Affects Land Stream Deposits

Delta Sedimentary deposit, commonly triangular, that forms where a stream enters a standing body of water Figure 11.6c Nile River delta © 2012 John Wiley & Sons, Inc. All rights reserved. How Water Affects Land Stream Deposits

Figure 11.7 Disappearing coastline, Mississippi River delta © 2012 John Wiley & Sons, Inc. All rights reserved. How Water Affects Land Stream Deposits

How Water Affects Land Large-Scale Topography of Stream Systems Figure 11.8 Mississippi River drainage basin © 2012 John Wiley & Sons, Inc. All rights reserved.

What a Geologist Sees—Drainage Basins Drainage basin of Wadi Al Masilah, south Yemen © 2012 John Wiley & Sons, Inc. All rights reserved.

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 © 2012 John Wiley & Sons, Inc. All rights reserved. How Water Affects Land Large-Scale Topography of Stream Systems

How Water Affects Land Lakes Lakes are standing bodies of water that have open surfaces, in direct contact with the atmosphere. Figure 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 © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource Figure 11.11b Mississippi River flood, May 2011 © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource Hydrograph Graph plotting discharge vs. time to record the flooding of a stream Figure A hydrograph or stream discharge © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource Figure Coastal flooding © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource Figure 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 Resource Surface 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. © 2012 John Wiley & Sons, Inc. All rights reserved.

Water as a Hazard and a Resource Surface Water Resources Figure Principal watersheds of the world © 2012 John Wiley & Sons, Inc. All rights reserved.

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

Fresh Water Underground Groundwater Subsurface water contained in pore spaces in regolith and bedrock Water table The top surface of the saturated zone Figure Water under the ground © 2012 John Wiley & Sons, Inc. All rights reserved.

Fresh Water Underground 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 Porosity in rocks and sediment © 2012 John Wiley & Sons, Inc. All rights reserved.

Fresh Water Underground How Groundwater Moves Percolation Groundwater seeps downward Flows under the influence of gravity Recharge Replenishment of groundwater Figure How groundwater flows © 2012 John Wiley & Sons, Inc. All rights reserved.

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 © 2012 John Wiley & Sons, Inc. All rights reserved. Fresh Water Underground How 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 Aquifers, confined and unconfined © 2012 John Wiley & Sons, Inc. All rights reserved. Fresh Water Underground Where Groundwater Is Stored

Figure 11.20a Artesian water Figure 11.20b Frozen artesian well, New York © 2012 John Wiley & Sons, Inc. All rights reserved. Fresh Water Underground Where Groundwater Is Stored

Fresh Water Underground Figure Wells: year-round and seasonal © 2012 John Wiley & Sons, Inc. All rights reserved.

Fresh Water Underground Figure Subsidence © 2012 John Wiley & Sons, Inc. All rights reserved.

Fresh Water Underground Figure The forgotten oil spill © 2012 John Wiley & Sons, Inc. All rights reserved.

Freshwater Underground When Groundwater Dissolves Rock Karst topography Sinkholes Cave Underground open space A cavern is a system of connected caves Figure a & b Karst © 2012 John Wiley & Sons, Inc. All rights reserved.

Amazing Places: Lechuguilla Cave a. A bush of aragonite c. “Pool fingers” b. Soda straws d. Gypsum crystals © 2012 John Wiley & Sons, Inc. All rights reserved.

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.