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Chapter 9 - Rivers, Streams, and Water Underground |
| Flowing water is a primary force affecting changes to the landscape. This chapter focuses on the interactions of water with earth materials, on the surface and underground. Understanding how water interacts with the landscape and materials underground are essential to managing water resources and protection of people and property from the effects of floods, droughts, and water contamination. |
1. Give an overview of the hydrologic cycle.
2. Identify the factors that control the flow of water.
3. Explain how streams transport and deposit sediments.
4. Describe the features of stream valleys.
5. Identify the types of drainage networks and drainage patterns.
6. Explain the development of a stream valley over time.
7. Discuss how deltas form.
8. Portray the general distribution of underground water.
9. Explain the difference between porosity and permeability and how these relate to the movement of groundwater.
10. Define the water table.
11. Describe springs, wells, and artesian wells.
12. List some problems associated with groundwater withdrawal and explain groundwater contamination.
13. Illustrate how groundwater can affect geology.
14. How and where do caverns form?
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| Keywords and Essential Concepts |
1. Give an overview of the hydrologic cycle.
hydrosphere—All the waters on the Earth's surface, such as oceans, lakes, rivers, and streams. Earth's oceans cover about 70% of the surface and contains 97.25% of the water.
hydrology—the science concerned with the properties of the earth's water, especially its movement in relation to the land's surface. The study of groundwater is geohydrology.
stream—a flow of water in a channel or bed, as a brook, rivulet, or small river. |
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The water cycle
(or hydrologic cycle) |
California weather patterns influencing precipitation |
California precipitation and stream map |
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Reservoir
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Volume / 106, km3
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Percent of total
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Oceans
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1370 |
97.25 |
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Ice caps and glaciers
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39 |
2.05 |
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Deep groundwater
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5.3 |
0.38 |
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Shallow groundwater
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4.3 |
0.30 |
| Lakes |
0.125 |
0.01 |
| Soil moisture |
0.065 |
0.005 |
| Atmosphere |
0.013 |
0.001 |
| Rivers |
0.0017 |
0.0001 |
| Biosphere |
0.0006 |
0.00004 |
| Total |
1408.7 |
100 |
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evaporation—the physical conversion of a liquid into a vapor.
transpiration—The process by which water in plants is transferred as water vapor to the atmosphere.
condensation—the conversion of atmospheric water vapor into liquid water or ice (causing precipitation).
precipitation—in meteorology usage: rain, snow, sleet, or hail that falls to the ground; in geology usage: the action or process of precipitating a substance from a solution.
rainshadow—the downwind side of a mountain range (or high volcano) that partially blocks the the flow of moist air, forcing precipitation on the prevailing windward side, and creates more arid conditions on the downwind side. |
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2. Identify the factors that control the flow of water.
drainage basin—a region drained by a principle stream extending from upland headwater regions down to where the stream merges with another body of water (a larger stream or river, lake, or ocean). A divide is a line that marks the boundary between two drainage basins.
stream discharge—the volume of water to pass a given point on a stream bank per unit of time, usually expressed in cubic meters of water per second.
stream gradient—the grade (slope) measured by the ratio of drop in a stream per unit distance, usually expressed as feet per mile or meters per kilometer. |
Worlds Rivers
| River Name |
Length (km) |
Length (miles) |
Drainage area (km²) |
Average discharge (m³/s) |
Outflow |
| Amazon |
6,992 |
4,010 |
6,915,000 |
175,000 |
Atlantic Ocean |
| Ganges - Brahmaputra - Meghna |
2,948 |
1,832 |
1,635,000 |
42,470 |
Bay of Bengal |
| Congo |
4,371 |
2,716 |
3,822,000 |
41,200 |
Atlantic Ocean |
| Yangtze (Chang Jiang) |
6,380 |
3,964 |
1,940,000 |
35,000 |
East China Sea |
| Orinoco |
2,140 |
1,330 |
880,000 |
33,000 |
Atlantic Ocean |
| Paraná
(Río de la Plata) |
3,998 |
2,484 |
3,100,000 |
25,700 |
Atlantic Ocean |
| Yenisei |
5,550 |
3,449 |
2,580,000 |
18,040 |
Kara Sea |
| Lena |
4,260 |
2,647 |
2,490,000 |
16,200 |
Laptev Sea |
| Mississippi |
6,270 |
3,896 |
2,980,000 |
16,200 |
Gulf of Mexico |
| Mekong |
4,023 |
2,500 |
811,000 |
14,800 |
South China Sea |
| Ganges |
2,510 |
1,560 |
907,000 |
13,159 |
Padma River |
| Ayeyarwady |
2,170 |
1,348 |
411,000 |
13,000 |
Andaman Sea |
| Amur
(Heilong) |
4,352 |
2,714 |
1,855,000 |
11,400 |
Sea of Okhotsk |
| Ob' - Irtysh |
5,410 |
3,449 |
2,990,000 |
10,300 |
Gulf of Ob |
| Mackenzie - Peace - Finlay |
4,241 |
2,635 |
1,790,000 |
10,300 |
Beaufort Sea |
| Saint Lawrence |
3,058 |
1,900 |
1,030,000 |
10,100 |
Gulf of Saint Lawrence |
| Niger |
4,167 |
2,589 |
2,090,000 |
9,570 |
Atlantic Ocean |
| Volga |
3,692 |
2,294 |
1,380,000 |
8,060 |
Caspian Sea |
| Zambezi |
2,574 |
1,599 |
1,331,000 |
7,070 |
Indian Ocean |
| Indus |
3,200 |
2,000 |
1,165,000 |
6,600 |
Arabian Sea |
| Nile |
6,650 |
4,132 |
3,349,000 |
5,100 |
Mediterranean Sea |
| Western US Rivers |
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| Columbia |
2,250 |
1,450 |
415,211 |
7,500 |
Pacific Ocean |
| Colorado |
2,333 |
1,450 |
390,000 |
1,200 |
Pacific Ocean |
| Rio Grande |
3,057 |
1,900 |
570,000 |
82 |
Gulf of Mexico |
| Sacramento River |
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820 |
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3. Explain how streams transport and deposit sediments.
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| Profile of a river drainage |
River features |
gravel bar along a mountain stream |
stream flow—streams move downslope under the influence of gravity. In straight channels, stream water moves as laminar parallel vectors, but with increasing speed and when objects hinder flow, the water becomes turbulent, constantly mixing. With increasing speed and turbulence stream water can carry more sediment (and larger particles) is suspension and as bedload.
flood—an overflowing of a large amount of water beyond its normal confines—inundating areas that are typically dry at least part of the year). Floods are linked to seasonal precipitation patterns (such as monsoons or spring snow melt) or catastrophic events (such as intense rainstorms, collapse of natural or manmade dams or levees).
turbulence—the often violent or unsteady movement and mixing of air or water, or of some other fluid.; a most important factor influencing sediment transport in a stream.
meandering—a meander is a bend in a sinuous watercourse. Meandering is the process when the faster-moving water in a river erodes the outer banks and widens its valley, and the slower-moving water on the inner side of the bend becomes a place where sediments are deposited. As a result, rivers tend to constantly change their course over a floodplain over time. |
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| Composition of dissolved components in seawater and freshwater in streams |
How sediments move in a stream |
Cross section of a stream |
Stream channel flow |
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5. Identify the types of drainage networks and drainage patterns.
| drainage pattern—a pattern created by stream erosion over time that reveals characteristics of the kind of rocks and geologic structures in a landscape region drained by streams. |
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| Stream drainage patterns can reflect the structure and composition of bedrock |
braided streams form in stream valleys overloaded with available sediments, back filling valleys with sediments. |
V-shaped stream valleys in eroding headwater region of Guadalupe River on Loma Prieta Peak, California |
Colorado River in the Grand Canyon, Arizona
Canyons form where stream erosion dominates over deposition. |
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4. Describe the features of stream valleys.
Parts of a river system
headwaters—the source region of primary precipitation catchment, including snow melt and other surface runoff, and groundwater discharge from springs.
gully—a water-worn ravine or trench-like depression where water runs off the a hilly or mountainous landscape, causing erosion.
waterfall—cascade of water falling from a height, formed when a river or stream flows over a precipice or steep incline.
rapid—A fast-flowing and turbulent part of the course of a river or stream where a change in gradient and shape of the channel changes, commonly associated with gravel bars or obstructions (bedrock and boulders) in the river bed.
tributaries—a tributary is a stream that flows into another stream or river (rather than a lake or sea). Tributaries combine to be a part of a large drainage basin.
river channel—the path of a river; the size and shape of a channel depends on the volume of water flowing in it, the gradient of the stream, and the nature of rock and sediments exposed in the river bed.
stream flow—the amount of water moving downstream. The discharge (cross sectional volume of the channel times the velocity of moving water and sediment in the water and along the bottom of the stream bed).
floodplain—a flat, low-lying area along a river that gets covered with water when the river floods, overflowing its natural levee. Slow moving storm water drops fresh sediment on floodplains.
riverbank—land immediately exposed along a river during non-flood conditions, but sculpted by flowing water during high water conditions. River banks can include cutbanks (stream-cut exposures of bedrock and older stream sediments), natural levees (buildups of sediments along the path of the river channel deposited by floodwaters), gravel bars, and point bars.
wetlands—lowland areas where water covers the surface, at least part of the year. Also called swamps, marshes, or bogs. Wetlands provide habitat to many varieties of plants and animals.
mouth—where a river or stream enters a larger body water (lake or ocean). Deltas form at the mouths of rivers.
delta—an accumulation of sediments at the mouth of a river that may consist of a network of distributary channels, wetlands, bars, tidal flats, natural levees and beaches that typically shift from on location to another. Delta shape is dependent of dominant current conditions where the mouth of the river: tide-, sea wave-, and storm-dominated.
oxbow—a crescent lake on a stream floodplain formed when a meandering stream channel is cut off and isolated by changes in a stream channel.
splay—a small fan-shaped or outspread alluvial deposit formed where an overloaded stream breaks through a levee (artificial or natural) and deposits its material (often coarse-grained) on the floodplain. |
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| Meandering stream |
Formation of an oxbow lake |
Mississippi River meanders |
Splay and distributaries |
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| Stream in flood |
River in flood |
2011 flood in Pakistan |
2009 Flood in Grand Forks, North Dakota |
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6. Explain the development of a stream valley over time.
base level—the lowest level to which a land surface can be reduced by the action of running water, typically equivalent to the lowest point a river or stream can reach entering the ocean or other large body of water. Base level of a stream entering the ocean will rise and fall with changes in sea level.
stream terrace—one of a possible series of level surfaces on a stream valley flanking and parallel to a stream channel and above that marks the level of a floodplain in the geologic past. |
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Rejuvenated meanders
Goosenecks of the San Juan
New Mexico |
Formation of stream terraces along a rejuvenated stream |
Formation of stream terraces along a rejuvenated stream |
Terraces along Arroyo Seco Canyon, California |
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7. Discuss how deltas form.
| delta—a wedge or apron-shaped deposit of sediments at the mouth of a river where it enters a large body of water (ocean or lake). |
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| Amazon River Delta |
Nile River Delta |
Lena River Delta, Siberia |
Indus River Delta |
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| Yellow River Delta |
Mississippi River Delta |
Mississippi Birdfoot Delta |
Colorado River Delta |
Great Flood Disasters
| Year |
Flood Area |
Death Toll |
Comments |
| 1931 |
Huang He (Yellow) River, China |
1,000,000 to 3,700,000 |
The "Yellow" river gets its name because of its high silt content. The silt contributes to be buildup of its expansive floodplain. |
| 1887 |
Huang He (Yellow) River, China |
900,000 to 2,000,000 |
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| 1938 |
Huang He (Yellow) River, China |
500,000 - 900,000 |
This flood was cause by Chinese military forces cutting through levees in order to flood area occupied by Japanese invasion forces. It worked, kinda. |
| 1642 |
Huang He (Yellow) River, China |
300,000 |
This flood was cause by rebel forces cutting through dikes along the city of Kaifeng. |
| 1975 |
Ru River, Banqiao Dam, China |
230,000 |
The collapse of the Banquia Dam, along with others, following a heavy rain caused by a typhoon. was the worst dam-related disaster in history. |
| 1931 |
Yangtze River, China |
145,000 |
Historical records show that Yangtze has had more than 1,000 recorded floods in Chinese history. |
| 1099 |
Netherlands and England |
100,000 |
This disaster was caused by a combination of high tides and storms causing flooding in low-lying areas. |
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8. Portray the general distribution of underground water.
| groundwater—water beneath the land's surface, filling pore spaces in saturated soil and rock; water that supplies wells and springs. |
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| Features associated with water underground |
Groundwater map of the US |
hydrology—the science concerned with the properties of the earth's water, especially its movement in relation to the land's surface. The study of groundwater is geohydrology.
aquifer—a porous and permeable rock or sediment layer, such as a sand or sandstone, containing groundwater that can be used to supply wells.
aquitard—a zone or layer of low permeability adjacent to an aquifer; the permeability is so low it cannot transmit any useful amount of water. Aquitards act as confining layers to confined aquifers. Confined aquifers can be used as water storage.
aquiclude—an impermeable body of rock or stratum of sediment, or an impermeable fault zone, that acts as a barrier to the flow of groundwater. |
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9. Explain the difference between porosity and permeability and how these relate to the movement of groundwater.
porosity—the state of being porous, or the ratio of the volume of all the pores (gas- or fluid-filled space) in a material to the volume of the whole.
permeability—a measure of the ability of a porous material (rock or unconsolidated sediments) to transmit fluids.
Darcy's Law—the law that the rate at which a fluid flows through a permeable substance per unit area is equal to the permeability, which is a property only of the substance through which the fluid is flowing, times the pressure drop per unit length of flow, divided by the viscosity of the fluid. |
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| Examples of porous and permeable materials |
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10. Define the water table.
water table—the level below which the ground is saturated with water. The water table is influenced by the gravitational flow of water underground, typically following the general topography of a landscape, but can be changed by the extraction of water from a well, or construction of a dam. The groundwater table rises and falls with changes in seasonal precipitation.
phreatic zone—the zone of saturated rock or sediment below the water table where pore spaces between grains or within fractures are mostly filled with water (also called zone of saturation).
vadoze zone—also termed the unsaturated zone, is the typically shallow subsurface interval between the land surface and the underlying phreatic zone or zone of saturation). The vadose zone extends from the top of the ground surface to the water table.
capillary fringe— a subsurface layer above the water table in which groundwater seeps up from a water table by capillary action to fill pores. |
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| Water table |
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11. Describe springs, wells, and artesian wells.
spring—any natural occurrence where water flows to the surface of the earth from below the surface, typically in locations where the water table in an aquifer meets the ground surface, allowing water to discharge onto the surface or into a body of water (stream, lake, ocean).
well—a hole dug or drilled in the ground that descends through the water table for the purpose of extraction of fluids (water, oil, and gas). Wells in unconfined aquifers will fill with water to the level of the water table.
artesian well—a well drilled through impermeable strata to reach water in a confined aquifer capable of rising to the surface by internal hydrostatic pressure.
head—the height that groundwater will rise in a confined well under artesian water pressure.
drawdown—A reduction in the volume of water in a lake or reservoir (surface or underground).
cone of depression—an inverted cone-like depression in the water table caused by groundwater extraction in a well in an unconfined aquifer. |
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| Wells and groundwater |
Cone of depression |
influent stream—a stream that contributes water to the zone of saturation of groundwater and develops bank storage.
effluent stream—a stream that is fed by groundwater seeping to the surface.
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12. List some problems associated with groundwater withdrawal and explain groundwater contamination.
subsidence—the lowering of the land surface, examples include downwarping by folding, crustal extension, gravitational collapse or other tectonic forces. Subsidence also occur in areas where extensive extraction of water or petroleum allows pore spaces between grains or fractures in rock to collapse, reducing volume, and resulting in subsidence of the land's surface.
salt water intrusion—the contamination of groundwater by seawater caused by too much well water withdrawal from an unconfined coastal aquifer. |
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| Subsidence in the Houston-Galveston area |
Saltwater intrusion caused by over pumping |
Point source and non-point source pollution |
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13. Illustrate how groundwater can affect geology.
karst—a region of irregular terrain underlain by limestone and is characterized by numerous caves, sinkholes, fissures, and underground streams.
pseudokarst—a region of irregular terrain that resembles karst but that is not formed by the dissolution of limestone; usually a rough-surfaced lava field in which ceilings of lava tubes have collapsed.
sinkhole—a cavity in the ground, typically in limestone bedrock, caused by water erosion and providing a route for surface water to disappear into cavernous passages underground. |
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| Lake-filled sinkholes of central Florida |
Sinkhole collapse in central Florida |
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How and where do limestone caverns form?
Cavern and karst features are a result of the chemical reactions between the mineral calcite (CaCO3), water, and carbon dioxide. The reactions of the solid (calcite bearing rock) and water and CO2 (from the air) result in the formation an aqueous solution bearing dissolved cations of calcium (Ca++) and bicarbonate anions (-HCO3). Calcium-rich water is called "hard water."
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Chemistry of calcium carbonate reactions
in the environment |
| cavern—an underground passage formed by dissolution of rock (typically limestone) by flowing groundwater. "Cave" is often used as a substitute for the more correct term "cavern." |
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| Carbonate depositional environments |
Great Barrier Reef, Australia |
Permian Reef, West Texas and New Mexico |
El Capitan Reef exposed on Guadalupe Peak, Texas |
travertine—White or light-colored calcareous rock deposited from mineral springs; or a common name for freshwater limestone deposits. Cavern speleothems are typically consist of travertine.
speleothem—a structure formed in a cavern by the deposition of minerals (usually calcite) from water, including such features as stalactites, stalagmites, columns, flowstone, or other features found in caverns that form above the water table.
stalactite—a tapering structure hanging like an icicle from the roof of a cave, formed of calcium salts deposited by dripping water.
stalagmite—A mound or tapering column rising from the floor of a cave, formed of calcium salts deposited by dripping water and often eventually uniting with a stalactite to form a column. |
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| Karst and cavern features |
Karst regions of the United States |
Karst landscape evolution |
Karst weathering on Black Mountain, Santa Cruz Mountains, California |
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| Speleothems: flowstone, stalactite, stalagmites, and columns |
Stalactite, stalagmites, columns, flowstone, and travertine dams in Lehman Caverns, California |
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Website About Selected National Parks with Caverns
Guadalupe Mountains National Park
Carlsbad Caverns National Park
Great Basin National Park
Wind Cave National Park
Jewel Cave National Monument |
Quiz Questions
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