A Virtual Field Trip Through Earth's Dynamic Systems

A Virtual Field Trip Through Earth’s Dynamic Systems

A01_CHRI5019_WT.indd 1 05/12/14 5:24 PM Exploring Earth’s Dynamic Systems

Elemental Geosystems is organized around the natural flow of energy, materials, and information, presenting subjects in the same sequence in which they occur in nature—an organic, holistic Earth systems approach that is unique in this discipline. Offering current examples and modern science, Elemental Geosystems combines a structured learning path, student-friendly writing, current applications, outstanding visuals, and a strong multi- media program for a truly unique physical geography experience. . NEW! Chapter 8: Climate Change. Incorporating the latest climate change science and data, this new chapter covers paleoclimatology and mechanisms for past climatic change, climate feedbacks and the global carbon budget, the evidence and causes of present climate change, climate forecasts and models, and actions that we can take to moderate Earth’s changing climate.

244 Elemental Geosystems geosystemsnow Climate Change 8 Greenhouse Gases Awaken in the Arctic n the subarctic and tundra climate re A Positive Feedback Loop As sum Igions of the Northern Hemisphere, per mers become warmer in the Arctic, ennially frozen soils and sediment, known heat radiating through the ground as permafrost, cover about 24% of the land thaws the permafrost layers. Micro area. With Arctic air temperatures curren bial activity in these layers increases, tly rising at a rate more than two times that enhancing the breakdown of organ

of the midlatitudes, ground temperatures ic matter and releasing CO2 into the are increasing, causing permafrost thaw. atmosphere in a process known as This results in changes to land surfaces, microbial respiration. In anaerobic primarily sinking and slumping, that dam (oxygenfree) environments, such age buildings, forests, and coastlines (Fig- as lakes and wetlands, the pro ure GN 8.1). Permafrost thaw also leads to cess releases methane. Studies the decay of soil material, a process that show that thousands of methane releases vast amounts of carbon—in the seeps can develop under a single form of the greenhouse gases carbon di lake, a huge amount when multi

oxide (CO2) and methane (CH4)—into the plied by hundreds of thousands of atmosphere. lakes across the northern latitudes (Figure GN 8.2). Carbon in Permafrost Soils Permafrost Carbon dioxide and methane is, by definition, soil and sediment that re are major greenhouse gases, which main frozen for two or more consecutive absorb outgoing longwave radia ▲Figure GN 8.2 Methane lies under years. It lies under a thin “active layer,” tion and radiate it back toward Earth, en Arctic lakebeds and, like natural gas, is seasonally frozen ground that thaws every hancing the greenhouse effect and lead highly flammable.[Todd Paris/Fairbanks/ summer to provide substrate for seasonal ing to atmospheric warming. Methane is University of Alaska/AP Images.] grasses and other plants that absorb especially important because, although CO from the atmosphere. In winter, the 2 its relative percentage in the atmosphere rate faster than Arctic air temperatures, active layer freezes, trapping plant and is small, it is far more effective than CO2 releasing vast amounts of “ancient” car animal material before it can decompose at trapping atmospheric heat. Thus, a bon into the atmosphere. Scientists are completely. Over hundreds of thousands positive feedback loop forms: As tem actively researching the locations and of years, this carbonrich material has peratures rise, permafrost thaws, causing amounts of vulnerable permafrost, the become incorporated into permafrost a release of CO2 and CH4 into the atmo current and projected rates of thaw, and and now makes up roughly half of all the sphere, which causes more warming, the potential impacts to the permafrost– A February 2014 storm caused large waves and flooding along the southern coast of England, near Newhaven. Ongoing research shows that organic matter stored in Earth’s soils— leading to more permafrost thaw. carbon positive feedback. The thawing the frequency of intense weather events is increasing with climate change. [Toby Melville/Reuters/Corbis.] twice the amount of carbon that is stored Arctic is one of many immediate concerns in the atmosphere. The latest estimate Melting Ground Ice In addition to frozen we discuss in this chapter regarding the of the amount of carbon stored in Arctic soil and sediment, permafrost contains causes and impacts of changing climate keylearningconcepts permafrost soils is 1700 gigatonnes (or ground ice, which melts as the permafrost on Earth systems. 1700 billion tons). thaws. When the supporting structure provided by the ice is After reading the chapter, you should be able to: question and explore: To learn about ▼Figure GN 8.1 Blocks of melting permafrost collapse removed, land surfaces • scientific tools used to study NASA’s Carbon in Arctic Reservoirs Vul- Describe into the Beaufort Sea, Alaska. [USGS Alaska Science Center.] collapse and slump. nerability Experiment (CARVE), which paleoclimatology. Subsurface soils are measures CO and CH gas emissions in then exposed to sun 2 4 • Discuss several natural factors that influence Earth’s permafrost regions, go to http://science1. light, which speeds up climate and describe climate feedbacks, using nasa.gov/missions/carve/ (the mission microbial processes, examples. website) or http://www.nasa.gov/topics/ and to water erosion, earth/features/earth20130610.html#. • List the key lines of evidence for present global climate which moves organic UhwYVj_pxXJ (mission background and change and summarize the scientific evidence for carbon into streams early results). anthropogenic forcing of climate. and lakes, where it is • Discuss climate models and summarize some climate mobilized into the at mosphere. Research projections. suggests that this pro • Describe several mitigation measures to slow rates of cess may release bursts

climate change. of CO2 and CH4 into the atmosphere, in contrast to the slower topdown melting of permafrost. 212 Elemental Geosystems Permafrost soils are now warming at a Water Use THEhumanDENOMINATOR 6 245

WATER RESOURCES IMPACT HUMANS HUMANS IMPACT WATER RESOURCES • Freshwater, stored in lakes, rivers, and groundwater, is a critical • Climate change affects lake depth, thermal structure, and resource for human society and life on Earth. associated organisms. M08_CHRI5019_08_SE_C08.indd 244 03/12/14• Drought 1:51 PM M08_CHRI5019_08_SE_C08.inddresults in water deficits, 245 decreasing regional water supplies • Water projects (dams and diversions) redistribute03/12/14 1:51 PMwater over and causing declines in agriculture. space and time. • Groundwater overuse and pollution depletes and degrades the 6a Desalination is an important resource, with side effects such as collapsed aquifers and saltwater supplement to water supplies in regions with large variations contamination. in rainfall throughout the year 6b The third largest reservoir and declining groundwater in the world, Lake Nasser reserves. This plant in is formed by the Aswan Barcelona, Spain, uses the High Dam on the Nile River process of reverse osmosis to in Egypt. Its water is used remove salts and impurities. for agricultural, industrial, and domestic purposes, as well as for hydropower. c NEW! The Human Denominator summarizes Human-Earth relationships, interactions, and challenges for the 21st century through dynamic visuals, including maps, photos, graphs, and

diagrams. Blue Marble–Next Generation image shows December land surface topography and bathymetry.

Quadishaya Quadishaya Reservoir Reservoir 6d

0 5 10 MILES Euphrates 0 5 10 MILES Euphrates River River 0 5 10 KILOMETERS 0 5 10 KILOMETERS

160

150

140 September 7, 2006 130 The Itaipu Dam and power plant on the Paraná River bordering Brazil and Paraguay produces more 120 Reservoir level (m) electricity annually than the Three Gorges Dam in September 15, 2009 China. Itaipu Reservoir displaced over 10,000 people 2003 2004 2005Year 2006 2007 2008 2009 and submerged Guaira Falls, formerly the world’s Data from GRACE reveal a rapid decline in reservoir levels from 2006 to 2009 along the largest waterfall by volume. Euphrates River in the Middle East; Quadishaya Reservoir is an example. The graph shows the surface-level decline, with dates of the images marked. About 60% of the volume loss is attributed to groundwater withdrawals in the region. ISSUES FOR THE 21ST CENTURY • Maintaining adequate water quantity and quality will be a major issue. Desalination will increase to augment freshwater supplies. • Hydropower is a renewable energy resource; however, drought-related streamflow declines and drops in reservoir storage interfere with production. • Drought in some regions will intensify, with related pressure on groundwater and surface water supplies.

A01_CHRI5019_WT.indd 2 M06_CHRI5019_08_SE_C06.indd 212 03/12/14 1:44 PM 05/12/14 5:24 PM Visualizing Processes & Landscapes

. NEW! Geosystems in Action provide highly-visual presentations of core physical processes and critical chapter concepts.

386 Elemental Geosystems Chapter 12 River Systems 387 eandering channels curve eandering from side channels to side in curve a snakelike from side pattern to side and in usually a snakelike occur pattern where andlow-gradient usually occur streams where flow low-gradient through streams flow through Stream MeanderingStream Process Meandering Process Stream valley landscape: Stream valley landscape: fine sediments. Meanders fine form sediments. because Meandersthe portion form of the because stream the with portion maximum of the velocity stream shifts with maximumfrom one sidevelocity of the shifts stream from to one side of the stream to 12.2a 12.2a GE Over time, stream meandersOver migrate time, stream laterally meanders across a migratestream valley,laterally acrossA neck a hasstream recently valley, been eroded,A neck forming has recently a cutoff been eroded, forming a cutoff M the other as theM stream bends, the other thus as affecting the stream erosion bends, and thus deposition affecting along erosion the andstream’s deposition banks along (GIA 12.1).the stream’s Through banks these (GIA 12.1). Through these eroding the outside of bendseroding and fillingthe outside the insides of bends of bends. and filling Narrow the insidesand of straightening bends. Narrow the stream andchannel. straightening The the stream channel. The bypassed portion of the streambypassed may become portion a of the stream may become a “scour-and-fill” processes,“scour-and-fill” a meandering processes, stream moves a meandering position laterally stream acrossmoves itsposition valley laterallyand creates across a distinctive its valley landscapeand creates (GIA a distinctive 12.2). landscape (GIA 12.2). areas between meandersareas are necks between. When meanders discharge are increases, necks. When the discharge increases, the o stream may scour throughstream the neck, may forming scour through a cutoff the. neck, forming a cutoffmeander. scar or an oxbow lake.meander scar or an oxbow lake. systems

Direction of flow Direction of flow 12.1a Proﬁle12.1a of a MeanderingProﬁle of Stream a Meandering Stream The cross sections show howThe the cross location sections of maximum show how flow the velocity location shifts of maximum from the flowcenter velocity along shiftsa straight from stretch the center of the along stream a straight stretch of the stream channel to the outside bendchannel of a meander. to the outsideThe oblique bend viewof a meander.shows how The the oblique stream view erodes, shows or “scours,” how the streaman undercut erodes, bank or “scours,”on the an undercut bank on the outside of a bend, while depositingoutside aof point a bend, bar while on the depositing inside of thea point bend. bar on the inside of the bend. Cutoff Cutoff Maximum Maximum Areas of maximum velocityAreas of maximum velocity velocity velocity meandering StreamS

Point bar deposition: Point bar deposition: in

On a bend’s inner side, streamOn a bend’s inner side, stream action 12

velocity decreases, leading tovelocity decreases, leading to Neck Neck deposition of sediment and deposition of sediment and forming a point bar. forming a point bar.

A cutoff forms on the ItkillikA cutoffRiver, formsnorth slopeon the of Itkillik the Brooks River, northRange, slope Alaska. of the Brooks Range, Alaska. 12 action in

12.2b Formation12.2b of anFormation Oxbow Lake of an Oxbow Lake meandering StreamS The diagrams below showThe the diagrams steps often below involved show in the forming steps anoften oxbow involved lake; in this forming an oxbow lake; this photo corresponds to Stepphoto 3, the corresponds formation of to a Stepcutoff. 3, Asthe stream formation channels of a cutoff. shift, As stream channels shift, Pool Pool these processes leave characteristicthese processes landforms leave on characteristic a floodplain. landforms on a floodplain. (deep) (deep) Step 1: Step 1: Step 2: Step 2: A neck is forms where a lengtheningA neck ismeander forms where a lengthening meander Over time, the neck narrows asOver erosion time, the neck narrows as erosion loops back on itself. loops back on itself. undercuts the banks. undercuts the banks.

Neck Neck systems

o Stream Stream Point Point meander meander bar bar Undercut bank erosion: Undercut bank erosion: Undercut Undercut GE Areas of maximum stream velocityAreas of maximum stream velocity bank bank (darker blue) have more power(darker to blue) have more power to erode, so they undercut the stream’serode, so they undercut the stream’s banks on the outside of a bend.banks on the outside of a bend.

Cutbank Cutbank Step 3: Step 3: Step 4: Step 4: Eventually, the stream erodesEventually, through the stream erodes through An oxbow lake forms as sedimentAn oxbow lls the lake area forms as sediment lls the area the neck, forming a cutoff. the neck, forming a cutoff. between the new stream channelbetween and itsthe old new meander. stream channel and its old meander.

Cutoff Cutoff 12.1b 12.1b 130 Elemental Geosystems Oxbow Oxbow Active Erosion AlongActive a Erosion Meander Along a Meander lake lake Notice how this stream in NoticeIowa has how eroded this stream a steep in Iowa has eroded a steep cutbank on the outside of cutbanka bend. on the outside of a bend. f cusstudy 4.1 Sustainable resources Wind Power: An EnergyExplain: ExplainResource the relationship forExplain: betweenthe Explain Present stream the relationshipvelocity, and between Future stream velocity, erosion, and deposition in theerosion, formation and of deposition a meander. in the formation of a meander.

he principles of wind power are an- of relatively flat prairies or an area with 25%–30% of the time, only small-scale use Animation Tcient, but the technology is modern, katabatic or monsoonal winds. Many of wind power is economically feasible.Meandering Follow up: In your own words,Follow describe up: Inthe your sequence own words, describe the sequence and the benefits are substantial. Scientists developing countries are located in Although most U.S. wind power is Streams of steps in the process that formsof steps an oxbowin the process lake. that forms an oxbow lake. estimate that wind as a resource could areas blessed by such steady winds, such land-based, offshore wind development Visit the Study Area in MasteringGeography™Visit the Study Area in to MasteringGeography™ explore meander and oxbow to explore lake meanderformation. and oxbow lake formation. GEOquiz GEOquiz potentially produce many times more as the trade winds across the tropics. In has high potential. The proposed Cape energyVisualize: than is currently Study a geosciences in demandVisualize: animation on Studya a geosciencesother areas, animationAssess: local winds Demonstrate are favorable. understandingAssess: Demonstrate of meanderWind understandingFarm and near Cape of meander Cod, Massachu and - 1. Explain: Explain the processes1. Explain: that Explain cause thea gentle processes bend that2. cause Summarize: a gentle Summarizebend 2. the Summarize: process by Summarize which a stream, the process over by which a stream, over of meander and oxbow lakeof meanderformation. and oxbow lake formation.oxbow lake formation (if assignedoxbow lake by instructor).formation (if assigned by instructor). along a stream to becomealong a deeply a stream looping to become meander. a deeply loopingtime, could meander. produce the landscapetime, could in produce the GIA12.2a the landscape photograph. in the GIA12.2a photograph. global scale. Yet, despite386 the available For example, in the California Coast setts, was recently approved as thehttp://goo.gl/ySMJp5 387 technology, wind-power development Ranges, land and sea breezes blow nation’s first offshore project. Proponents continues to be slowed, mainly by the between the Pacific Ocean and Central hope that despite the additional expense changing politics of renewable energy. Valley, peaking in intensity from April to of installation, offshore production will in- October, which happens to match peak crease, especially along the Eastern sea- electrical demands for air conditioning board, where population centers are close The NatureM12_CHRI5019_08_SE_C12.indd of Wind Energy 386 M12_CHRI5019_08_SE_C12.indd12/3/14 12:55 PM 387 12/3/14 12:55 PM and irrigation pumping during the hot together. At least 12 offshore projects Power generation from wind depends on summer months. are currently under consideration, most of site-specific characteristics of the wind The potential of wind power in the them on the East Coast. resource. GeosystemsFavorable settings for consis- in Action include links to mobile-ready media and MasteringGeography, as well as United States is enormous (Figure 4.1.1). The appeal of land-based wind- tent wind are areas (1) along coastlines In the Midwest, power from the winds power development is enhanced by the influencedGeoQuizzes by trade winds and westerly and integrated active learning tasks that ask students to analyze, explain, infer, or of North and South Dakota and Texas income it brings. Farmers in Iowa and winds; (2) where mountain passes con- alone could meet all U.S. electrical needs. Minnesota receive about $2000 in annual strict air flow and interior valleys develop predict based Whereon winds the are sufficient, information electricity income presented. from electrical production by a thermal low-pressure areas, thus drawing can be generated by groups of wind leased turbine and about $20,000 a year air across the landscape; and (3) where turbines (in wind farms) or by individual from electrical production by an owned localized winds occur, such as an expanse Chapter 14 Glacial and Periglacial Landscapes 449 installations. If winds are reliable less than turbine—requiring only one-quarter acre

V-shaped valley

(a) Preglacial Horn Col Arête Cirque

Medial moraine Truncated spurs

Bergschrund

Main glacier Suitable for power development (b) Glacial

4.0 5.0 6.0 7.0 8.0 9.0 10.0 Wind speed (m/s) ▲Figure 14.11 An alpine valley, showing preglacial and glacial landscape. Inset photos are of an arête in Canada, a horn in Antarctica, ▲Figure 4.1.1 Wind-speed map of the contiguous United States. The map shows predicted average wind speeds at a height of 80 m a cirque in Nepal, and a bergschrund in Spitsbergen. [Arete by Fred & (164 ft) above the ground. Areas with wind speeds greater than 6.5 m/s (21 ft/s) are considered suitable for power development. The map has Randi Hirschmann/RGB Ventures/SuperStock/Alamy. Cirque by Galen Rowell/ a spatial resolution of 2.5 km (1.6 mi). [NREL and AWS Truepower.] Corbis. Horn and bergschrund by Bobbé Christopherson.]

depression or pass, forming a col. A horn, or pyramidal valley sides. In the cirques where the valley glaciers origi- peak, results when several cirque glaciers gouge an indi- nated, small mountain lakes called tarns have formed. ▲ An unparalleled visual program includes a variety of illustrations,vidual mountain summit from maps,all sides. Most famous photographs, is Some cirques contain small, circular, stair-stepped lakes, M04_CHRI5019_08_SE_C04.indd 130 03/12/14 12:44 PM the Matterhorn in the Swiss Alps, but many others occur called paternoster (“our father”) lakes for their resem- and composites, providing authoritative examples and applicationsworldwide. A bergschrund is a crevasse,of physical or wide crack, blance geography to rosary (religious) beads. Paternoster lakes may that separates flowing ice from stagnant ice in the upper form from the differing resistance of rock to glacial pro- reaches of a glacier or in a cirque. Bergschrunds are often cesses or from damming by glacial deposits. and Earth systems science. covered in snow in winter, but become apparent in sum- In some cases, valleys carved by tributary glaciers are mer when this snow cover melts. left stranded high above the main valley floor because the Figure 14.12 shows the same landscape at a time of primary glacier eroded the main valley so deeply. These warmer climate, when the ice retreated. The glaciated hanging valleys are the sites of spectacular waterfalls. valleys now are U-shaped, greatly changed from their How many of the erosional forms from Figures 14.11 and previous stream-cut V form. Physical weathering from 14.12 can you identify in Figure 14.13? (Look for arêtes, the freeze–thaw cycle has loosened rock along the steep cols, horns, cirques, cirque glaciers, U-shaped valleys, cliffs, and it has fallen to form talus slopes along the and tarns.)

M14_CHRI5019_08_SE_C14.indd 449 12/3/14 1:52 PM

A01_CHRI5019_WT.indd 3 05/12/14 5:24 PM Real World Applications

Elemental Geosystems integrates current real events and phenomena and presents the most thorough and integrated treatment of systems trends and climate change science, giving students compelling reasons for learning physical geography.

. Geosystems Now open each chapter with interesting, current . Focus Studies present detailed discussions of critical applications of physical geography and Earth systems science. physical geography topics, emphasizing the applied relevance New Geosystems Now Online features direct students online to of physical geography today. related resources. 332 Elemental Geosystems

162 Elemental Geosystems f cusstudy 10.1 Natural Hazards Earthquakes in Haiti, Chile, and Japan: A Comparative Analysis geosystemsnow n 2010 and 2011, three quakes struck areas city of Port-au-Prince, which has been minimal damage, in large part due to the Sand Dunes Protect Coastlines Inear major population centers, causing destroyed by earthquakes several times, fact that the country enacted strict build- during Hurricane Sandy massive destruction and fatalities. These mostly notably in 1751 and 1770. The ing codes in 1985 (Figure 10.1.1b). The Altitude (m)earthquakes—in the countries of Haiti, Chile, total damage there from the 2010 quake result was a fraction of the human cost Windward and Japan—all occurred at plate boundaries exceeded the country’sLeeward $14 billion gross compared to the Haiti earthquake. uring the winter of 2013, several sand is deposited on shore, it and ranged in magnitudeChapter from 13 M 7.0Oceans, to M 9.0 Coastaldomestic Systems, product (GDP). and In Wind developing Processes The Japan427 quake resulted in an months after Hurricane Sandy, many is reworked by wind processes 2˚C 2500 D (Figure 10.1.1 and Table 10.1.1). countries such as Haiti, earthquake damage enormous and tragic human fatality count residents along New Jersey’s coastline into the shape of dunes. Dunes MAR is worsenedDAR by inadequate construction, (Figure 10.1.1c), mainly due to the massive added their discarded Christmas trees along seacoasts are either fore- 5˚C 2000 7˚C to carefully stacked lines of trees acting dunes, where sand is pushed algae they die. Scientists are currently trackingThe Humanthis Dimension lack of enforced building codes, and the Pacific Ocean tsunami (defined as a set of Condensation level difficulties of getting food, water, and medi- seismic sea waves; discussed in Chapter 13). as “seeds” for new sand dune formation up the seaward-facing slope, worldwide phenomenon, which is occurring in theThe Carib 2010 Haiti- earthquake hit Chinookan impover- or , which form far- 8˚C 1500 12˚Ccal help to those in need (Figure 10.1.1a). When an area of ocean floor some 338 km along several area beaches. The trees backdunes ished country where little of thewinds infrastruc- were intended to catch windblown sand ther away from the beach and bean Sea and the Indian Ocean as well as off the shores The Maule, Chile, earthquake, which (N–S) by 150 km (210 mi by 93 mi) snapped ture was built to withstand earthquakes. to begin the dune formation process, in are protected from onshore 11˚C occurred just 6 weeks later, caused only and was abruptly lifted as much as 80 m of Australia, Indonesia, Japan, Kenya, Florida,1000 Texas,Over 2 andmillion people live in the capital 17˚C one of many such restoration efforts along winds (blowing toward theDAR the Atlantic coast. In the face of Sandy’s beach); backdunes are more Hawai‘i.16˚C Possible causes include local pollution,500 disease, 23˚C winds, houses and neighborhoods with stable and may be hundreds of 80° 75 °70° 65° 76° 74° 72° ATLANTIC OCEAN 34° protective dunes in place experienced years old. Most areas of coastal sedimentation, changes in ocean salinity, and increasing Santiago CUBA HAITI DOMINICAN PACIFIC less damage than those that were more dunes are relatively small in 21˚Csize 0 REPUBLIC 28˚C oceanic acidity. 20° OCEAN Maule exposed to and closer to the ocean. (especially when compared 516 Elemental Geosystems Port-au-Prince 36° with desert dune fields that ARGENTINA Warm, moistSince 2000, scientists have acknowledged thatJAMAICA the PUERTO Hot, dry Concepción Dune Protection versus Ocean Views may cover large portions of Caribbean Sea RICO The effectiveness of dune systems as warming of sea-surface temperatures, linked to green- 15° CHILE continents). ◀ Figure 16.12 Epiphytes using38° a tree trunk for support, Wash- protection from wave erosion and storm Along the Atlantic coast,Ocean house warming of the atmosphere, is a greater threat to cor- Rain shadow surge during Hurricane Sandy, far from foredunes are moving inland ington. Epiphytic club mosses are common in the temperate rain for- being a subtle statistical phenomenon, as sea level rises and storm als than local pollution or other environmental problems. est of Olympic National Park. [Don Johnston/Alamy.] was easily observed by local residents. energy increases with (a)climate Prevailing winds force warm, moist air upward against a mountain range, producing adiabatic cooling, eventual saturation and net However, the fostering of large and Although a natural process, coral bleaching is now occur- change. In developedcondensation, areas, cloud formation, and precipitation. On the leeward slope, as the “dried” air descends, compressional heating warms it, sometimes obtrusive sand dunes near this landward retreat of fore- ring at an unprecedented rate as average ocean tempera- the shoreline is controversial in coastal dunes impinges on humanand de evaporation- dominates, creating the hot, relatively dry rain shadow. communities with million-dollar homes. velopment. When storms Videotures climb▲Figure higherGN 13.2 Coastal with damage climate from change. The 1998 record El For such dunes to function as barriers to occur, dune movement is Hurricane Sandy Sandy in Mantoloking, New Jersey. View erosion, they must sit between ocean- ▲Figure 5.24 OrographicNiño event precipitation, caused the unstable die-off conditions of perhaps 30% of the world’s intensified, and either dune looking west before and after Hurricane CrITICAlthinking 16.1 front property and the sea, thus block- erosion assumed.or sand deposi Review- Figuresreefs. 5.13 InSandy. and2010, The 5.14yellow scientists asarrow you points work to thereported through same the one of the most rapid ing ocean views and decreasing property tion, or temperatureboth, occurs within changes in partfeature (a) A in landscape each image. [USGS.] affected by orographic Mutualism? Parasitism? Where Do We Fit In? values (Figure GN 13.1). For many land- the developed area of the and severe coral bleaching and mortality events on record precipitation is inhttp://goo.gl/Yj3FWj part. [(b) Terra MODIS, NASA/GSFC.] (a) Destruction in Port-au-Prince, Haiti, in 2010. The owners, establishing dunes for storm pro- coast (Figure GN 13.2). restored dunes about 4.6 m (15 ft) in ome(b) A collapsedscientists bridge are in Santiago, asking Chile, whether after the our human soci- near Aceh, Indonesia, on the northern tip of the islandquake epicenter of was along multiple surface faults M8.8 earthquake hit Maule, 95 km (60 mi) away. tection means financial loss in the short height, the community still escaped Figure 13.20 Coastal salt marsh. This wetland along the Long and a previously unknown▲ subsurface thrust fault. etyThe epicenterand the was physical on a convergent systems plate boundaryof Earth constitute a Video term, even if long-term protection is the Dune Restoration Efforts The establish- excessive damage, since the dunes ab- S N Sumatra. Some species declined 80% in just a few months, Island coast, New York, is protectedbetween from the developmentNazca and South Americanby a private plates. The Making of result. ment of new foredunes replenishes the sorbed much of the storm’s impact. global-scale symbiotic relationship of mutualism,MapMaster which is a Superstorm sand supply▼Figure and protects 5.25 structures Cloudsin and responseand rain shadow to increased produced sea-surface by orographic temperatures across land NORTHtrust. Land135° trusts are145° nonprofit, independent organizations that Thus, many local communities are sup- 40° Coastal Dune Geomorphology Coas- infrastructure, making this a potentially KOREA sustainable, or of parasitism, which is unsustainable.World/PhysicalEnvironment Af- lifting. Over the Sierra Nevadaporting in Californiadune restoration, and asNevada, evidenced the rain work with landownersJAPAN to conserve natural resources and open space. tal sand dunes consist of sediment sup- the region. Many of these corals previously were resilient Sea of Sendai Tsunami Hazard worthwhile investment of money and by the 2013 Christmas tree initiative. Be- Japan shadow produced by descending, warming air contrasts with the Since the vast majorityPACIFIC of coastalter reviewing areas are the privately definitions owned, of landthese trusts terms, what is your plied by the work of ocean waves and effort for communities along the New SOUTHWashington in the facecause vegetationof other is importantecosystem for dune disruptions, including the Honshu OCEAN by fluvial processes that move sedi- KOREA Tokyo Jersey cloudsshoreline. on Many the expertswindward point side stabilization, (note the thewind planting direction of grasses at the is bottom of have becomeNagoya critical tools35° forresponse wetland to protection. that statement? [Brooks HowKraft/Corbis.] well do our human eco- http://goo.gl/k6HaNa ment onto deltas and estuaries. Once out thatthe dunes photo). are not [Robert a guarantee Christopherson.]Sumatra–Andaman of another protectiveand strategy tsunami the being fungus inem -2004. provides structure and physical sup- nomic systems coexist with the need to sustain the plan- storm protection Asbraced sea-surface by New Jersey temperaturesresidents. In this continue to rise and and that Sandy’s port. Their mutualism allows the two to occupy a niche et’s life-supporting natural systems? Do you characterize chapter, we discuss coastal systems, wind Rainier station winds and oceanstorm processes,acidification and dune formation. worsens, coral losses will continue. trees, shrubs, palms, thisand as ferns mutualism, that growparasitism, in these or something inter- else? surge were strong in which neither could survive alone. Lichen developed Yakima station enough to Forerode more information and Internet links, see the Global tidal areas as well as for the habitat, which is known as a S question and explorefrom anFor information earlier parasitic relationship in which the fungi some largeCoral natu- Reefand links Monitoring to research on dunesNetwork in New at http://www.gcrmn.org/. mangrove swamp (Figure 13.21). These ecosystems have ral dune systems Jersey and alongbroke the Atlantic into coast, the see algal cells. Today, the two organisms have along the Atlantic http://marine.rutgers.edu/geomorph/evolved into a supportive and harmonious symbiotica high diversity rela- of species that are tolerant of saltwater Seaboard. How- geomorph/_pages/dunes.html. More on Abiotic Influences ever, in Bradley coastal dune geomorphologytionship. is atThe http:// partnership of corals and algae discussedinundation, in but generally intolerant of freezing tempera- NevadaBeach, NewCoastal Jer- www.nature.com/scitable/knowledge/ WetlandsChapter 13 is another example of mutualismtures in a symbi(especially- A as number seedlings). of abiotic Mangrove environmental roots are factorstypi- influence spe- sey, where the library/coastal-dunes-geomorpholo- storm erodedIn some gy-25822000 coastal. areas,otic relationship sediments are(Figure rich 16.1d).in Windwardorganic mat- cally visible abovecies the distributions, waterline,Leeward interactions,but the root andportions growth. For example, several miles of ter, leading to lush plantAnother growth form and of spawningsymbiosis(b) The wetter grounds(c)is Honshu parasitism windward Island, Japan,that slopes, in after reach which thenear quake belowRainier and the stationthe distribution water are(d) in Tsunamisurface contrast movesof sometoprovide ashore, the plants Iwanuma, a habitat andJapan. animalsIwanuma for is depends on drier leewardtsunami. landscapes The epicenter nearwas on Yakima a convergent station in Washington.20 km (12.4 mi) south of Sendai, the city closest to the ◀ Figure forGN 13.1 fish, Constructed shellfish, dunes.one Restored and species sandotherCalifornia dunes benefits organisms. and A another coastal plateis marsh harmed boundary between bya themultitude the Paci cassoci and- Northof specialized photoperiodepicenter. life, the forms. duration The of root light systems and dark over a 24-hour shield homes in Mantoloking, New Jersey, from an incoming American plates. nor’easterenvironment a few weeks after Hurricane of thisSandy.ation. [Sharontype Often Karr/FEMA.] provides this association optimal habitat involves for var a parasite- maintain living offwater qualityperiod. byMany trapping plants sediment require and longer taking days for flowering ▲Figure 10.1.1 The 2010–2011 Haiti, Chile, and Japan earthquakes and the 2011 Japan tsunami. [(a) Julie Jacobson/AP ied wildlife. Unfortunately,a host organism, these suchwetland as a ecosystems fleaWorld livingImages. War on (b)are Martin a I.dog. Bernetti/GettyWeatherup A excessparasitic Images. systems nutrients(c) and (d) andKyodo/Reuters.]seemed seedand germination,preventto them erosion to besuch by as stabilizing ragweed (Ambrosia ). Other quite fragile andrelationship are threatened may by eventually human development migratingkill the host—an air massaccumulated example “armies” is doingsediments.plants battle require along longer fronts. nights A to stimulate seed production, (Figure 13.20). parasitic mistletoe (Phoradendronfront is), awhich place lives of atmosphericMangrove on and ecosystemsdiscontinuity,such as the arepoinsettia a threatenednarrow ( Euphorbia by ongoing pulcherrima ), which M13_CHRI5019_08_SE_C13.indd 405 12/3/14 1:49 PM zone forming a line of conflict between two air masses of Leeward As discussedcan in Chapterkill Windwardvarious 6, wetlands kinds of are trees. permanently removal, owing toneeds falsely at conceivedleast 2 months fears thatof 14-hour they harbor nights to start flow- different temperature,disease pressure, or pestilence; humidity, to pollution, wind direction especially from agri- or seasonally saturatedA thirdwith water,form of and symbiosis as such,M10_CHRI5019_08_SE_C10.indd is they commensalism have 332 , in which ering. These species cannot survive in equatorial regions 12/3/14 12:50 PM hydric soils (withone anaerobic, species benefitsor oxygen-free, and the andconditions) other speed, experiences and cloudcultural neither development. runoff; towith overharvesting, The little leading daylength edge especially ofvariation; a in they develop are instead- restricted and support hydrophyticharm nor vegetation benefit. An (plants example that growis the in remora ing (a countries sucker whereto latitudesthey supply with firewood; appropriate to storm photoperiods, surges although water or wet soil).fish) Coastal that lives wetlands attached are to ofsharks two andgeneral consumes in areasthe waste where protectiveother factors barrier may islandsalso affect and their coral distribution. reefs c GeoReports offer types—mangroveproduced swamps as(occurring the shark between eats its prey. 30° NEpiphytic and haveplants, disappeared; such andIn terms to climate of entire change, ecosystems, since manair and- soil tempera- Georeport30° S latitude) 5.2 Mountains andas saltorchids, marshes cause are another(occurringrecord rainsexample; at latitudes these of “air plants”groves growrequire atures stable are sea important, level for long-term since they survival. determine the rates at a wide variety of brief ount30° Waialeale,and higher). on the Thison islandthe distribution branches of Kaua’i, and Hawai‘i, is dictated trunks rises of 1569by trees, tempera m (5147 using -ft) them aboveAccording for sea physi level. to- On the itswhich windwardFood chemicaland slope, Agriculture reactionsrain- Organization proceed. Precipitation of and water fall averaged 1234 cm (486 in., or 40.5 ft) a year for the years 1941–1992. In contrast, the rain-shadow side of Kaua’i M ture—specifically,cal the support occurrence (Figure of 16.12 freezing). conditions. the United Nations,availability 20% of arethe alsoworld’s critical, mangroves as is water were quality—its min- interesting facts, received only 50 cm (20 in.) of rain annually. If no islands existed at this location, this portion of the Pacific Ocean would In tropical regions,A finalsediment symbiotic accumulation relationship on coast is -amensalismlost from, 1980in toeral 2005. content, A 2011 salinity, study usingand levels satellite of pollution data and toxicity. receive only an average 63.5 cm (25 in.) of precipitation a year. (These statistics are from established weather stations with a consistent lines provides siteswhich for one mangroves, species harms the name another for thebut is notreported affected that theAll remaining of these factorsextent workof global together mangroves to determine the distri- examples, and record of weather data; several stations claim higher rainfall values, but do not have dependable measurement records.) applications to comple- Cherrapunji, India, is 1313 m (4309itself. ft) above This sea typically level at 25° occurs N latitude, either in thewhen Assam two Hills organisms south of the Himalayas.butions of Summer species mon- and communities in a given location. soons pour in from the Indian Ocean andare inthe competition Bay of Bengal, and producing one deprives 930 cm (366 the in.,other or 30.5 of foodft) of rainfallor in 1 month.Pioneering Not surpris- work in the study of species distribu- ment and enrich the ingly, Cherrapunji holds the all-time precipitationhabitat or whenrecord fora plant a single produces year, 2647 chemical cm (1042 in., toxins or 86.8 that ft), and fortion every was other done time by intervalgeographer and explorer Alexander von from 15 days to 2 years. The average annualdamage precipitation or kill other there plants. is 1143 cmFor (450 example, in., 37.5 ft),black placing walnut it second Humboldtonly to Mount (1769–1859), Waialeale. the first scientist to write about chapter reading. Georeporttrees excrete 13.3 aOcean chemical acidification toxin through impacts their corals root sys- the distinct zonation of plant communities with chang- s thetems oceans into absorbthe soil more that excess inhibits carbon the dioxide,growth theirof other acidity plants increases ingand elevation.potentially damagesAfter several coral formations, years of studyan in the Andes A interactionbeneath thatthem. scientists are actively researching. A 2013 study examinedMountains Mediterranean of Peru,red coral von (Corallium Humboldt rubrum hypothesized) that colonies under more acidic conditions in a laboratory and discovered reduced growth rates of 59% and abnormal skeleton development when compared with colonies growing under current ocean conditions. The test conditions were at a pH of 7.8 (which

would occur with CO2 levels of 800 ppm, forecasted for the year 2100) as compared to recent conditions of pH 8.1 (380 to 400 ppm). M05_CHRI5019_08_SE_C05.indd 162 Georeport 16.1 Sea turtles navigate using Earth’s magnetic field 03/12/14 1:40 PM he fact that birds and bees can detect the abiotic influence of Earth’s magnetic field and use it for finding direction is Twell established. Small amounts of magnetically sensitive particles in the skull of the bird and the abdomen of the bee provide compass directions. Recently, scientists found that sea turtles detect magnetic fields of different strengths and inclinations (angles). This means that the turtles have a built-in navigation system that helps them find certain locations on Earth. Log- gerhead turtles hatch in Florida, crawl into the water, and spend the next 70 years traveling thousands of miles between North America M13_CHRI5019_08_SE_C13.indd 427 and Africa around the subtropical high-pressure gyre in the Atlantic Ocean. The females return to where they were12/3/14 hatched 1:51 PM to lay their eggs. In turn, the hatchlings are imprinted with magnetic data unique to the location of their birth and then develop a more global sense of position as they live a life swimming across the ocean.

iv part 2 The Water, Weather, and Climate Systems

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A01_CHRI5019_WT.indd 4 05/12/14 5:24 PM 372 part 2 The Water, Weather, and Climate Systems 12 River Systems

378 Elemental Geosystems

folded rock structures that vary in resistance to erosion. (a) Dendritic (e) Rectangular A Refined LearningParallel structuresPath direct the principal streams, while smaller dendritic tributary streams are at work on nearby slopes, joining the main streams at right angles, as in a plant trellis. Elemental Geosystems provides a structured learning path that helpsThe students remaining drainage patterns in Figures 12.5c–g Five Finger Rapids on the Yukon River in Yukon, Canada, is formed by four basalt islands that divide the river channel into fiveare narrow responses passages, to other specific structural conditions: achievewith only a one deeper easily passable. understanding The rapids were a major obstacle of physical to poorly constructed geography rafts and boats duringthrough the Klondike active Gold Rush learning. of 1898, claiming many lives. [Bobbé Christopherson.] • A radial drainage pattern (c) results when streams flow off a central peak or dome, such as occurs on a volcanic mountain. keylearningconcepts • Parallel drainage (d) is associated with steep slopes. (b) Trellis (f) .Annular Critical Thinking activities• A integratedrectangular throughoutpattern (e) is chapterformed by sections a faulted give and After reading the chapter, you should be able to: jointed landscape, which directs stream courses in 376 Elemental Geosystems students an opportunity to stop, check, and apply their understanding. • Sketch a basic drainage basin model and identify patterns of right-angle turns. different types of drainage patterns by visual • Annular patterns (f) occur on structural domes, with basinsexamination. that empty into different bodies of water surround- concentric patterns of rock strata guiding stream CRitiCalthinking 12.1courses (discussed in Chapter 10). •ing Explain a continent; the concepts for ofNorth stream America, gradient and these base bodies level are the Locate Your Drainage• A derangedBasin pattern (g) with no clear geometry and no Pacificand describe Ocean, the the relationship Gulf of between Mexico, stream the velocity,Atlantic Ocean, true stream valley occurs in areas such as the glaci- Hudsondepth, width,Bay, and discharge.the Arctic Ocean. The principal drain- etermine the name ofated the drainageshield regions basin ofwithin Canada, which northern Europe, and •age Explain divides the processesand drainage involved basins in fluvial in erosionthe United and States and Dyour campus is located.some Where parts of are Michigan its headwaters? and other states. Canadasediment are transport. mapped in Figure 12.3. These divides form Where is the river’s mouth?Occasionally, If you are in thedrainage United patterns States occur that seem dis- (c) Radial (g) Derangedor Canada, use Figure 12.3 to locate the larger drainage •water-resource Describe common regions stream andchannel provide patterns a andspatial framework cordant with the landscape through which they flow. basins and divides for your region, and then take a look forexplain water-management the concept of a gradedplanning. stream. For example, a drainage system may initially develop TM In North America, the great Mississippi–Missouri– at this region on Googleover Earthhorizontal. Does strata any that regulatory have been deposited on top of • Describe the depositional landforms associated with organization oversee planninguplifted, foldedand coordination structures. As for the the streams erode into the Ohiofloodplains River systemand alluvial drains fan environments. some 3.1 million km2 (1.2 mil- drainage basin you identified?older folded Can strata, you find they topographic keep their original course, down- 2 •lion List andmi describe), or 41% several of typesthe ofcontinental river deltas and United States maps online that cover cuttingthis region? into the rock in a pattern contrary to its structure. (Figexplain ure 12.3). flood probabilityWithin this estimates. basin, rainfall in northern Penn- sylvania feeds hundreds of small streams that flow into CRitiCalthinking 12.2 the Allegheny River. At the same time, rainfall in western which eventually flows on past New Orleans and dis- ▲ KeyPennsylvania Learning Concepts feeds hundreds at the beginning of streams of that every flow into the perses into the Gulf of Mexico.Identifying Each contributing Drainage Patternstributary, (d) Parallel xamine the photograph in Figure CT 12.2.1, where chapterMonongahela help students River. identify The two the riverskey knowledge then join at and Pittsburgh ▲largeFigure or 12.5 small, Common adds drain its- discharge, pollution, and sediment you see two distinct drainage patterns. Of the seven age patterns. Each pattern E skills tothey form will the acquire Ohio throughRiver. The study Ohio of theflows chapter. southwestward load to the larger river. In ourtypes example, illustrated sediment in Figure 12.5, weath which -two patterns are is a visual summary of all the and at Cairo, Illinois, connects with the Mississippi River, geologicered and and climaticeroded condi in- Pennsylvaniamost islike transported those in the aerial thousands photo? Looking back to Fig- tions of its region. [(a) through ure 12.1a, which drainage pattern is prevalent in the area (g) After A. D. Howard, “Drainage around Mount Mismi in Brazil? Explain your answer. The M12_CHRI5019_08_SE_C12.indd 60°N 372 12/3/14 12:55 PM . 70°N at the end of 80°N Key Learning170°E Concepts Reviews analysis in geological interpretation: next time you fly in an airplane, look out the window to each chapter feature summaries, narrative defini- A summation,” Bulletin of American observe the various drainage patterns across the land- ARCTIC OCEAN Association of Petroleum Geologists scape. Arctic 20°W tions, a list of key terms with page numbers, and 51 (1967): 2248. Reprinted by permis- Bering drainage sion of AAPG whose permission is 180° review questions. Sea required for further use.] Beaufort Chapter 12 River Systems 401 60°N THE DENOMINATOR 12 Rivers, Floodplains, and Deltas human Sea Baf n Bay 30°W dendritic drainage (Figure 12.5a).Arctic This treelike pattern RIVER SYSTEMS IMPACT HUMANS HUMANS IMPACT RIVER SYSTEMS keylearningconceptsreview drainage 170°W Paci c (from the Greek word dendron, meaning “tree”) is similar • Humans use rivers for recreation and have farmed fertile floodplain • Dams and diversions alter river flows and sediment loads, affect- drainage Arctic to that of many natural systems, such as capillaries in the Circle soils for centuries. ing river ecosystems and habitat. River restoration efforts include Sketch a basic drainage basin model and identifyYUKON different level occurs when something interrupts the stream’s abil- • Flooding affects human settlements on floodplains and deltas. dam removal to restore ecosystems and threatened species. types of drainage patterns by visual examination. humanity circulatory to achieveARCTIC base system, COASTlevel, suchor AND the as ISLANDSaveins dam or in a landslideleaves, or that the 40°W • Rivers are transportation corridors and provide water for municipal • Urbanization, deforestation, and other human activities in water- Fluvial processes are stream-related. The basic fluvial sysroots- ofblocks trees. a streamEnergy channel. expenditure in the moving of water and industrial use. sheds alter runoff, peak flows, and sediment loads in streams. Discharge, a stream’s volume of flow per unit of time, Labrador tem is a drainage50°N basin, or watershed, which is an openand sediment through this drainage system is efficient is calculated by multiplying the velocity of the stream • Levee construction affects floodplain ecosystems; levee failures system. Drainage divides define theGulf catchment of (water- MACKENZIE Sea becauseby theits widthtotal lengthand depth of thefor abranches specific cross is minimized. section of the cause destructive flooding. receiving) area of a drainage basin. In any drainage basin, 160°W Alaska channel. Streams may have perennial, ephemeral, or in- water initially moves downslope in a thin film of sheet- The trellis drainage pattern (Figure 12.5b) is charac- 12a termittent flow regimes. Discharge usually increases in a flow, or overland flow. This surface runoff concentratesteristic in of dipping or folded topography.KEEWATIN SuchHudson drainage is LABR ADO 50°W downstream direction; however, in rivers in semiarid or Figure CT R12.2.1– Two drainage patterns dominate In June 2013, floodwaters rills, or small-scale downhillPACIFIC grooves, which may developseen in the nearly parallel mountain folds ofBay the Ridge ▲ NE arid regions, discharge may decrease with distance down- W 50°N following days of heavy this scene from centralFO Montana, in response to rock into deeper gullies and a stream course in a valley. Highand Valley Province in the eastern United States (shown U rainfall inundated Germany, PACIFIC stream as water is lost to evapotranspiration and water NORTHERN N ground that separates one valley from another and directs Hudson Bay structure and local relief.D [Bobbé Christopherson.] Austria, Slovakia, Hungary, OCEAN COASTAL PEACE– L in Figurediversions. 10.16). Here drainage patternsdrainage are influenced by QUEBEC A and the Czech Republic. sheetflow is an interfluve. Extensive mountain and high- ATHABASCA N According to local residents, A graph of streamCHURCHILL discharge over time for a specific D land regions act as continental divides that separate ma- FRASER NORTH SLOPE– water levels in Passau, place is called a hydrograph. Precipitation events in ur- GASPÉ Germany, were higher than jor drainage basins. Some regions, such as the Great Salt 150°W ban areas result in higher peakNELSON flows during floods. In de- any recorded in the past Lake Basin, have internalDRAINAGE drainage thatBASIN does not reach the SASKATCHEWAN 500 years. serts, a torrent of water that fills a stream channel during ocean, the only outlets DISCHARGEbeing evaporation and subsurface MARITIME 40°N or just after a rainstorm is a flash flood. COASTAL gravitational flow. CANADA: Northdrainage Atlantic millions m3 per year gradient (p. 379) hydrograph (p. 380) ST. Drainage density is determined by the numberPaci c and ASSINIBOINE– LAWRENCE length of channels in(millions a given acre-feet area perand year) is an expressiondrainage base level (p. 379) flash flood (p. 381) M12_CHRI5019_08_SE_C12.indd 378 RED 12/3/14 12:55 PM of a landscape’s topographicHudson Baysurface 682,000 appearance. (553) Drain- discharge (p. 379) GREAT 40°N COLUMBIA 60°W age pattern refers to Atlanticthe arrangement 670,000 (544) of channels in an LAKES area as determined byPaci c the steepness, 602,000 (488) variable rock resist- 7. Explain the base level concept. What happens to a Arctic 440,000 (356) ance, variable climate, hydrology, relief of the land, and stream’s base levelMISSOURI when a reservoir is constructed? NORTH Gulf of Mexico 105 (0.9) UPPER structural controls imposed by the landscape. Seven C ba- 8. What was the impact of flood dischargeMISSISSIPPI on the chan- ATLANTIC

A GREAT BASIN sic drainage patterns are generally found in nature: den- nel of the SanR Juan River near Bluff, Utah? Why did UNITED STATES: L Internal E these changesPP Otake place? OHIO dritic, trellis, radial, parallel, rectangular, annular, andI U D millions acre-feet per year F Drainage A Gulf/Atlantic 30°N R deranged. (millions m3 per year) O 9. Differentiate LO between a natural stream hydrograph drainage ATLANTIC O Atlantic R and oneC from an urbanized area. E drainage E 140°W Gulf/Atlantic 718 (886,000) N I S fluvial (p. 374) continental divide (p. 375) I P ES OCEAN Paci c 334 (412,000) A P N ARKANSAS–WHITE–RED I TEN 30°N drainage basin (p. 374)Atlantic 293drainage (361,000) pattern (p. 377) Explain the processes involved in fluvial erosion andS S sheetflow (p. 375) I sedimentLOWER transport. S SOUTH

S Continental divides COLORADO I ATLANTIC–

Water dislodges, dissolves, or removes surface materialM 1. Define the term fluvial. What is a fluvial process? GULF

R 2. What role is played by rivers in the hydrologic cycle? and moves it to new locationsRIO TEXAS–GULF in the process of erosionE . Sediments are laid down GRANDE by the process of depositionW . Hy- 3. What are the five largest0 rivers250 on500 Earth MILES in terms of O

discharge? Relate these to the weather patterns in draulic action is the erosive work of water caused by hy- 12c each area 20°Nand to regional0 250 potential500 KILOMETERS evapotranspira- draulic squeeze-and-release action to loosen and lift rocks and sediment. As this debris moves along, it mechanicallyGulf of 12b tion (PE) and precipitation (P)—concepts discussed Trop ic of C in Chapter 6. anerodescer the streambed further through a process ofMexico abrasion. 20°N Monsoon rains in August 2013 4. What is the basic organizational unit of a river sys- Streams may deepen their valley by channel incision, they caused flooding across Pakistan, tem? How is it identified130°W on the landscape? 120°WDefine may lengthen110°W in the process of headward erosion, or90°W they 80°W 70°E damaging over 80,000 homes, the several relevant key terms used. may erode a valley laterally in the process of meandering. affecting over a million people, and causing more than 200 5. In Figure 12.3, follow the Allegheny–Ohio– When stream energy is high, particles move down- fatalities. The Swat Valley in ▲MississippiFigure 12.3 river Drainage system to basinsthe Gulf and of Mexico. continental divides.stream in Continentalthe process of divides sediment (red transport lines) separate. The sedi the- major drainage basins that empty through northern Pakistan, pictured theAnalyze United the States pattern into of thetributaries, Pacific and Ocean, describe Atlantic Ocean,ment load and of aGulf stream of canMexico be dividedand, to into the three north, primary through Canada into Hudson Bay and the Arctic here, had the worst flooding in the channel. What role do continental divides play over a decade. Ocean. Subdividing these major drainage basins aretypes. major The river dissolved basins. load [After travels U.S. inGeological solution, Survey;especially The NationalChapter Atlas of Canada 10 G, 1985,lobal “Energy, Climate Mines, Systems v in this drainage? the dissolved chemicals derived from minerals such as and Resources Canada”; and Environment Canada, Currents of Change—Inquiry on Federal Water Policy—Final Report 1986.] 6. Describe drainage patterns. Define the various pat- limestone or dolomite or from soluble salts. The suspended terns that commonly appear in nature. What drain- In 2011, Americans spent $42 billion load consists of fine-grained, clastic particles held aloft on fishing-related activities. Streams age patterns exist in your hometown? Where you in the stream, with the finest particles not deposited until in Montana, Missouri, Michigan, ISSUES FOR THE 21ST CENTURY attend school? Utah, and Wisconsin are designated • Increasing population will intensify human settlement on floodplains the stream velocity slows nearly to zero. Bed load refers to “blue ribbon fisheries” based on and deltas worldwide, especially in developing countries, making more coarser materials that are dragged and pushed and rolled sustainability criteria such as water Explain the concepts of stream gradient and base level people vulnerable to flood impacts. along the streambed by traction or that bounce and hop quality and quantity, accessibility, and describe the relationship between stream velocity, and the presence of certain species. along by saltation. • Stream restoration will continue, including dam decommissioning and depth, width, and discharge. removal, flow restoration, vegetation reestablishment, and restoration A01_CHRI5019_WT.indd 5 Degradation occurs when sediment is eroded and 05/12/14 5:24 PM The gradient of a stream is the slope, or the stream’s drop channel incision occurs. If the load in a stream exceeds of stream geomorphology. in elevation per unit distance. Base level is the lowest- its capacity, aggradation occurs as sediment accumulates • Global climate change may intensify storm systems, including M12_CHRI5019_08_SE_C12.indd 376 12/3/14 12:55 PM elevation limit of stream erosion in a region. A local base on the bed of the stream channel. hurricanes, increasing runoff and flooding in affected regions. Rising sea level will make delta areas more vulnerable to flooding.

M12_CHRI5019_08_SE_C12.indd 401 12/3/14 12:56 PM Continuous learning before, during, & after class delivers engaging, dynamic learning opportunities—focusing on course objectives and responsive to each student’s progress—that are proven to help students absorb geography course material and understand challenging physical processes and geographic concepts. BEFORE CLASS Pre-Class Assignments Provide Students with a Preview of What’s to Come ▼ NEW! Mobile-Enabled Media Quick Response (QR) Codes integrated throughout each chapter empower students to use their mobile devices to learn as they read, providing instant access to over 80 Animations and Videos of real-world physical geography phenomena and visualizations of key physical processes. All media can be assigned with quizzes in MasteringGeography.

▶ Pearson eText in MasteringGeography gives students access to Elemental Geosystems, 8th Edition whenever and wherever they are online. The eText includes powerful interactive and cus- tomization features: • Now available on smartphones and tablets. • Seamlessly integrated videos and other rich media. • Fully accessible (screen-reader ready). • Configurable reading settings, including resizable type and night reading mode. • Instructor and student note-taking, highlighting, book- marking, and search.

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A01_CHRI5019_WT.indd 6 05/12/14 5:24 PM www.masteringgeography.com

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“My students are so busy and engaged answering Learning Catalytics questions during lecture that they don’t have time for Facebook.” (Declan De Paor, Old Dominion University)

What has teachers and students excited? Learning Catalytics, a “bring your own device” student engagement, assessment, and classroom intelligence system, allows students to use their smartphone, tablet, or laptop to respond to questions in class. With Learning Catalytics, teachers can: • Assess students in real-time using open-ended question formats to uncover student mis- conceptions and adjust lecture accordingly. • Automatically create groups for peer instruction based on student response patterns to optimize discussion productivity.

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▶ Encounter Activities provide rich, interactive Google Earth explorations of physical geography concepts to visualize and explore Earth’s landscape and physical processes. Available with multiple-choice and short answer questions. All Explorations include cor- responding Google Earth KMZ media files, and questions include hints and specific wrong-answer feedback to help coach students toward mastery of the concepts.

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Student Study Area Resources in MasteringGeography include: • Animations, Videos, MapMaster™ interactive maps • Practice quizzes, Glossary flashcards • “In the News” RSS feeds • Optional Pearson eText and more viii part 2 The Water, Weather, and Climate Systems

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Chapter 10 Global Climate Systems ix

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