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Earth Science, 13e. Tarbuck & Lutgens. Running Water and Groundwater Earth Science, 13e Chapter 5. Stanley C. Hatfield Southwestern Illinois College.

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Earth science 13e

Earth Science, 13e

Tarbuck & Lutgens


Running water and groundwater earth science 13e chapter 5

Running Water and GroundwaterEarth Science, 13eChapter 5

Stanley C. Hatfield

Southwestern Illinois College


Li River, China’s Guilin DistrictNote karst topography, in which groundwater has dissolved large volumes of limestone (more later).


Earth as a system the hydrologic cycle
Earth as a system: the hydrologic cycle

  • Illustrates the circulation of Earth’s water supply

  • Processes involved in the cycle

    • Precipitation

    • Evaporation

    • Infiltration

    • Runoff

    • Transpiration



Running water
Running water

  • Drainage basin

    • Land area that contributes water to a river system

    • A divide separates drainage basins





Running water1
Running water regardless of size.

  • Streamflow

    • Factors that determine

      velocity

      • Gradient, or slope

      • Channel characteristics

        • Shape

        • Size

        • Roughness

      • Discharge – volume of water flowing in the stream (generally expresses as cubic feet per second)


Gradient slope
Gradient (slope) regardless of size.

  • Parts of lower Mississippi: 10 cm/km

  • Mountain streams: 40 m/km

  • Steeper gradient has more energy,  more velocity


Discharge
Discharge regardless of size.

  • Measured in m3 or ft3 per second

  • Changes over time due to amount of precipitation in drainage basin


Measuring stream velocity
Measuring stream velocity regardless of size.

1 kph – 30 kph

Straight – highest at center

Curved– highest at outer bank


Running water2
Running water regardless of size.

  • Upstream-downstream changes

    • Profile

      • Cross-sectional view of a stream

      • From head (source) to mouth

        • Profile is a smooth curve

        • Gradient decreases from the head to the mouth

      • Factors that increase downstream

        • Velocity

        • Discharge


Running water3
Running water regardless of size.

  • Upstream-downstream changes

    • Profile

      • Factors that increase downstream

        • Channel size

      • Factors that decrease downstream

        • Gradient, or slope

        • Channel roughness


Longitudinal profile of a stream
Longitudinal regardless of size.profile of a stream



Running water4
Running water regardless of size.

  • The work of streams

    • Earth’s most important erosional agent

      • Downcut, widen streams

      • Transport sediment which can erode banks, channel, bedrock

  • MG: Sediment transport by streams


Running water5
Running water regardless of size.

  • Transportation – transported material is called the stream’s load

    • Dissolved load

      • From groundwater, dispersed through flow

      • Expressed in ppm

      • Velocity of streamflow has no effect on stream’s ability to carry dissolved load

      • Precipitation only if water chemistry changes


Running water6
Running water regardless of size.

  • Transportation – transported material is called the stream’s load

    • Suspended load

      • Biggest portion of river’s load

      • Usually fine particles s/a silt, clay but could be sand or gravel, especially during flood (which can also increase quantity)

      • Controlled by flow velocity and settling velocity (speed @ which particle falls through still fluid)

        • Slow settling + high flow = longer suspension

    • Bed load


Running water7
Running water regardless of size.

  • Suspended load, Colorado River


Running water8
Running water regardless of size.

  • Transportation – transported material is called the stream’s load

    • Bed load – solids are to large to be carried in suspension, settle along stream bed

      • Erosional action – move by rolling, sliding, saltation (jumping or skipping)

      • < 10% of total load


Running water9
Running water regardless of size.

  • The work of streams

    • Transportation

      • Load is related to a stream’s

        • Competence

          • maximum particle size

          • increases proportionately to square of velocity (swift streams have greater competence

        • Capacity

          • maximum load

          • related to discharge


Running water10
Running water regardless of size.

  • The work of streams

    • Transportation

      • Deposition

        • Caused by a decrease in velocity

        • Competence is reduced

        • Sediment begins to drop out

      • Stream sediments

        • Known as alluvium

        • Well-sorted deposits


Running water11
Running Water regardless of size.

  • Bedrock channels vs. alluvial channels

    • Bedrock – headwater, steep

    • May contain rapids/waterfalls

      • Rapid

        • section of river where river bed has a relatively steep gradient 

        • increase in water velocity and turbulence

        • river becomes shallower and has some rocks exposed above the flow surface


Running water12
Running Water regardless of size.


Running water13
Running Water regardless of size.

  • Bedrock channels vs. alluvial channels

    • Bedrock – headwater, steep

    • May contain rapids/waterfalls

      • Waterfall – place where water flows over a vertical drop in the course of a stream or river


Running water14
Running Water regardless of size.

  • Bedrock channels vs. alluvial channels

    • Alluvial – loosely consolidated sediment (alluvium)

      • Meandering

        • mostly suspended load

        • evolve over time as bends migrate floodplain

        • most erosion @ outside of bend


Running water15
Running Water regardless of size.

Cut bank – zone of active erosion

Point bar – coarser material deposited


Running water16
Running Water regardless of size.


Running water17
Running Water regardless of size.

  • Braided Streams

    • Complex network of diverging channels

    • Coarse grains are transported as bed load


South-looking photograph showing diamond-shaped bars and meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

South-looking photograph showing diamond-shaped bars and meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

Rakaia River, South Island New Zealand


Running water18
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Base level

    • Lowest point a stream can erode to

    • Two general types

      • Ultimate – sea level

      • Temporary, or local

    • Changing causes readjustment of the stream – deposition or erosion


Adjustment of base level to changing conditions
Adjustment of base level meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.to changing conditions


Running water19
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Stream valleys

    • Valley sides are shaped by

      • Weathering

      • Overland flow

      • Mass wasting

    • Characteristics of narrow valleys

      • V-shaped

      • Downcutting toward base level


Running water20
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Stream valleys

    • Characteristics of narrow valleys

      • Features often include

        • Rapids

        • Waterfalls

    • Characteristics of wide valleys

      • Stream is near base level

        • Downward erosion is less dominant

        • Stream energy is directed from side to side


Running water21
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Stream valleys

    • Characteristics of narrow valleys

      • Features often include

        • Rapids

        • Waterfalls

    • Characteristics of wide valleys

      • Stream is near base level

        • Downward erosion is less dominant

        • Stream energy is directed from side to side


V shaped valley of the yellowstone river
V-shaped valley of meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.the Yellowstone River


Continued erosion and deposition widens the valley see next slide
Continued erosion and deposition widens the meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.valley – see next slide


Land is uplifted meandering river downcuts
Land is uplifted – meandering river meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.downcuts


Running water22
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Features produced by deposition

    • Deltas

      • exist in ocean or lakes

      • formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river

      • Human activities s/a diversion of water, damscan radically alter delta ecosystems

        • dams block sedimentation which can cause the delta to erode away

        • use of water upstream can greatly increase salinity levels as less fresh water flows to meet the salty ocean water

        • Nile Delta and Colorado River Delta are some of the most extreme examples of the ecological devastation caused to deltas by damming and diversion of water.


Nile River delta meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.


Running water23
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Features produced by deposition

    • Natural levees

      • form parallel to the stream channel

      • commonly form around lowland rivers and creeks without human intervention

    • Area behind levee is characteristically poorly drained (water can not flow up the levee and into the river)

      • Marshes called backswamps result.

      • Yazoo tributaries

        • Since tributary stream can not enter river, it has to flow parallel to the river until it can breach the levee

        • Name comes from the Yazoo River, which runs parallel to the Mississippi River for 280 km (170 mi) before converging


Formation of natural levees by repeated flooding
Formation of natural meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.levees by repeated flooding


Running water24
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Features produced by deposition

    • Alluvial Fan - fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads, typically at the exit of a canyon onto a flatter plain

    • As stream's gradient decreases, it drops coarse-grained material

      • Reduces capacity of channel

      • Forces it to change direction and gradually build up a slightly mounded or shallow conical fan shape. 


Alluvial fan lake louise alberta
Alluvial Fan – Lake Louise, Alberta meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.


Running water25
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Floods and flood control

    • Floods are the most common geologic hazard

    • Causes of floods

      • Floods are caused by many factors and can be exacerbated by increased amounts of impervious surface or by other natural hazards such as wildfires, which reduce the supply of vegetation that can absorb rainfall.


Causes of floods
Causes of floods meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Heavy rainfall

  • Highly accelerated snowmelt

  • Severe winds over water

  • Unusual high tides

  • Tsunamis

  • Failure of dams, levees, retention ponds, or other structures that retain water


Running water26
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Floods and flood control

    • Engineering efforts

      • Artificial levees

        • Steeper slope than natural levee

        • Sometimes made of concrete

      • Flood-control dams

        • Store water, then let it out slowly

        • Destroy farmland, etc.

        • Trap sediment leading to erosion downstream


Running water27
Running water meandering braided stream channels, East Fork Toklat River, Alaska Range, Denali National Park, Alaska.

  • Floods and flood control

    • Engineering efforts

      • Channelization – altering channel

        • Clearing obstructions, dredging

        • Artificial cutoffs – increase gradient and velocity, lower chance of flooding

    • Nonstructural approach through sound floodplain management

      • Zoning regulations that minimize development and promote more appropriate land use



Same satellite view during flooding in 1993
Same satellite view during flooding in 1993 Mississippi River near St. Louis


Inside hurricane katrina
Inside Hurricane Katrina Mississippi River near St. Louis

  • Part 1

  • Part 2

  • Part 3

  • Part 4

  • Part 5


Water beneath the surface groundwater
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Largest freshwater reservoir for humans

  • Geological roles

    • As an erosional agent, dissolving by groundwater produces

      • Sinkholes

      • Caverns

    • An equalizer of stream flow


Water beneath the surface groundwater1
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Distribution and movement of groundwater

    • Distribution of groundwater

      • Belt of soil moisture

      • Zone of aeration

        • Unsaturated zone

        • Pore spaces in the material are filled mainly with air


Water beneath the surface groundwater2
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Distribution and movement of groundwater

    • Distribution of groundwater

      • Zone of saturation

        • All pore spaces in the material are filled with water

        • Water within the pores is groundwater

      • Water table – the upper limit of the zone of saturation


Features associated with subsurface water
Features associated with subsurface water Mississippi River near St. Louis


Water beneath the surface groundwater3
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Distribution and movement of groundwater

    • Distribution of groundwater

      • Porosity

        • Percentage of pore spaces

        • Determines storage of groundwater

      • Permeability

        • Ability to transmit water through connected pore spaces

        • Aquitard – an impermeable layer of material

        • Aquifer – a permeable layer of material


Water beneath the surface groundwater4
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Features associated with groundwater

    • Springs

      • Hot springs

        • Water is 6–9° C (10–15° F) warmer than the mean air temperature of the locality

        • Heated by cooling of igneous rock

      • Geysers

        • Intermittent hot springs

        • Water turns to steam and erupts


Old faithful geyser in yellowstone national park
Old Faithful geyser in Mississippi River near St. LouisYellowstone National Park


Water beneath the surface groundwater5
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Features associated with groundwater

    • Wells

      • Pumping can cause a drawdown (lowering) of the water table

      • Pumping can form a cone of depression in the water table

    • Artesian wells

      • Water in the well rises higher than the initial groundwater level


Formation of a cone of depression in the water table
Formation of a cone of Mississippi River near St. Louisdepression in the water table


Artesian systems
Artesian systems Mississippi River near St. Louis


Water beneath the surface groundwater6
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Environmental problems associated with groundwater

    • Treating it as a nonrenewable resource

    • Land subsidence caused by its withdrawal

    • Contamination


Water beneath the surface groundwater7
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Geologic work of groundwater

    • Groundwater is often mildly acidic

      • Contains weak carbonic acid

      • Dissolves calcite in limestone

    • Caverns

      • Formed by dissolving rock beneath Earth’s surface

      • Formed in the zone of saturation


Water beneath the surface groundwater8
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Geologic work of groundwater

    • Caverns

      • Features found within caverns

        • Form in the zone of aeration

        • Composed of dripstone

        • Calcite deposited as dripping water evaporates

        • Common features include stalactites (hanging from the ceiling) and stalagmites (growing upward from the floor)


Cave features in carlsbad caverns national park
Cave features in Carlsbad Mississippi River near St. LouisCaverns National Park


Water beneath the surface groundwater9
Water beneath the Mississippi River near St. Louissurface (groundwater)

  • Geologic work of groundwater

    • Karst topography

      • Formed by dissolving rock at, or near, Earth’s surface

      • Common features

        • Sinkholes – surface depressions

        • Sinkholes form by dissolving bedrock and cavern collapse

        • Caves and caverns

      • Area lacks good surface drainage


Features of karst topography
Features of karst topography Mississippi River near St. Louis


End of chapter 5

End of Chapter 5 Mississippi River near St. Louis


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