Surface WaterSurface Water

Chapter 6Chapter 6

Water CycleWater Cycle

6.1 Streams and Rivers6.1 Streams and Rivers River Systems (structure)River Systems (structure)

Tributary- a stream that runs into another Tributary- a stream that runs into another stream or riverstream or river

River system- a river and all of its tributariesRiver system- a river and all of its tributaries Drainage basin, or watershed- all the land Drainage basin, or watershed- all the land

that drains into the river either directly or that drains into the river either directly or through its tributariesthrough its tributaries Mississippi River systemMississippi River system

Divide- high land that separates one Divide- high land that separates one drainage basin from anotherdrainage basin from another Continental Divide in the Rocky MtnsContinental Divide in the Rocky Mtns

Headwaters/Source- Headwaters/Source- beginning of stream or beginning of stream or riverriver

Mouth- end of the Mouth- end of the stream or river where stream or river where it enters into another it enters into another body of waterbody of water

CharacteristicsCharacteristics Velocity- distance that water travels in Velocity- distance that water travels in

a given amount of timea given amount of time Related to the amount of energy that the Related to the amount of energy that the

water haswater has Erosion occurs more quicklyErosion occurs more quickly Other characteristics affect the velocityOther characteristics affect the velocity

Gradient- steepness of the slope of a Gradient- steepness of the slope of a stream or riverstream or river Steep at its source; gradual at sea levelSteep at its source; gradual at sea level

Characteristics cont…Characteristics cont… Discharge- the amount, or volume, of water that Discharge- the amount, or volume, of water that

passes a certain point in a given amount of timepasses a certain point in a given amount of time Not constant over length of a riverNot constant over length of a river Increases downstream as tributaries add more waterIncreases downstream as tributaries add more water Not constant year-round- increased Not constant year-round- increased

precipitation/melting snowprecipitation/melting snow Channel- the path through which the water Channel- the path through which the water

flows in a stream or riverflows in a stream or river Shallow, winding stream with many boulders has Shallow, winding stream with many boulders has

contact with surface area that causes it to slow down contact with surface area that causes it to slow down by friction by friction

Straight channel that is wide and deep has less Straight channel that is wide and deep has less surface area in contact with water, so velocity is surface area in contact with water, so velocity is greatergreater

6.2 Stream Erosion and 6.2 Stream Erosion and DepositionDeposition

Deposition- the process by which Deposition- the process by which materials are depositedmaterials are deposited Occurs because the river or stream no Occurs because the river or stream no

longer has enough energy to transport themlonger has enough energy to transport them Erosion by riversErosion by rivers

Running water wears down Earth’s surface Running water wears down Earth’s surface by breaking up bedrock and by removing by breaking up bedrock and by removing eroded rock and soil materialseroded rock and soil materials

Breaks up materials by mechanical meansBreaks up materials by mechanical means Abrasion mainly; in time, creates rounded Abrasion mainly; in time, creates rounded

boulders, pebbles, and sand grains from the boulders, pebbles, and sand grains from the cutting toolscutting tools

Transporting MaterialsTransporting Materials Two measures are used to describe the ability of Two measures are used to describe the ability of

a stream to transport materialsa stream to transport materials Competence- a measure that describes the maximum Competence- a measure that describes the maximum

size of the particles a stream can carrysize of the particles a stream can carry Capacity- a measure of the total amount of sediment a Capacity- a measure of the total amount of sediment a

stream can carrystream can carry Depend on the velocity and dischargeDepend on the velocity and discharge Vary along a stream and change throughout the Vary along a stream and change throughout the

yearyear High velocity + High discharge = large amount High velocity + High discharge = large amount

of sediment and larger sizes of sediment of sediment and larger sizes of sediment particlesparticles

Depositional Depositional FeaturesFeatures

Delta- a fan-shaped Delta- a fan-shaped deposit that forms deposit that forms when a river flows when a river flows into a quiet or large into a quiet or large body of waterbody of water River water comes to River water comes to

almost a standstill at a almost a standstill at a deltadelta

Distributaries- Distributaries- branches formed by branches formed by rivers flowing over its rivers flowing over its deltadelta

Responsible for delta’s Responsible for delta’s shapeshape

Formation is delicate Formation is delicate balance between balance between deposition and erosiondeposition and erosion

Stream ValleysStream Valleys

Narrow valleysNarrow valleys narrow V-shaped valley shows that the narrow V-shaped valley shows that the

stream’s primary work has been stream’s primary work has been downcutting toward base leveldowncutting toward base level

Features: Rapids and waterfallsFeatures: Rapids and waterfalls Wide valleysWide valleys

Downward erosion is less dominantDownward erosion is less dominant More energy is directed side to sideMore energy is directed side to side FloodplainFloodplain- the flat, low-lying portion of - the flat, low-lying portion of

a stream valley subject to periodic a stream valley subject to periodic floodingflooding

FloodplainsFloodplains

Streams that Streams that flow on flow on floodplains move floodplains move in meandersin meanders

Cutoffs- shorter Cutoffs- shorter channel channel segmentssegments

Oxbow lakes-Oxbow lakes- abandoned bend abandoned bend of a river/streamof a river/stream

FloodsFloods

Most caused by rapid spring snow melt Most caused by rapid spring snow melt or storms that bring heavy rains over a or storms that bring heavy rains over a large regionlarge region Ex: Mississippi River in 1993Ex: Mississippi River in 1993

Measures to control floodingMeasures to control flooding Artificial Levees- earthen mounds built on Artificial Levees- earthen mounds built on

the banks of the riverthe banks of the river Flood-control dam- store floodwater and Flood-control dam- store floodwater and

then let it out slowlythen let it out slowly Limits on floodplain development- Limits on floodplain development-

minimizing the development on floodplainsminimizing the development on floodplains

6.3 Water Beneath the 6.3 Water Beneath the SurfaceSurface

Much of the water in soil seeps downward Much of the water in soil seeps downward until it reaches the until it reaches the zone of saturationzone of saturation The area where water fills all of the open The area where water fills all of the open

spaces in sediment and rockspaces in sediment and rock Groundwater is the water within this zoneGroundwater is the water within this zone

Water tableWater table- upper limit of zone of - upper limit of zone of saturationsaturation

Zone of aeration-Zone of aeration- area above water table area above water table where the soil, sediment, and rock are not where the soil, sediment, and rock are not saturatedsaturated

GroundwaterGroundwater

MovementMovement Porosity- the percentage of Porosity- the percentage of

the total volume of rock or the total volume of rock or sediment that consists of sediment that consists of pore spacespore spaces

Permeability- the ability to Permeability- the ability to release a fluidrelease a fluid Aquitards- impermeable Aquitards- impermeable

layers that get in the way or layers that get in the way or prevent water movementprevent water movement

Aquifers- permeable rock Aquifers- permeable rock layers or sediments that layers or sediments that transmit groundwater freelytransmit groundwater freely

SpringsSprings

A flow of groundwater that emerges A flow of groundwater that emerges naturally at the ground surfacenaturally at the ground surface

Forms whenever the water table Forms whenever the water table intersects the ground surfaceintersects the ground surface Hot springsHot springs

6°C - 9°C warmer than average annual 6°C - 9°C warmer than average annual temperaturetemperature

Source of heat is cooling igneous rockSource of heat is cooling igneous rock GeysersGeysers

Intermittent hot spring or fountain in which a Intermittent hot spring or fountain in which a column of water shoots up with great force at column of water shoots up with great force at various intervalsvarious intervals

Above: Geyser formation

Below: Old Faithful Geyser Eruption

WellsWells Hole bored into the zone of saturationHole bored into the zone of saturation

Irrigation for agricultureIrrigation for agriculture Industrial useIndustrial use Home useHome use

Cone of depression- feature formed when too Cone of depression- feature formed when too much water is being drawn out in a short much water is being drawn out in a short period of timeperiod of time

Artesian wellArtesian well- any formation in which - any formation in which groundwater rises on its own under pressuregroundwater rises on its own under pressure water must be in an aquifer that is tilted so that water must be in an aquifer that is tilted so that

one end is exposed at the surfaceone end is exposed at the surface Must be aquitards both above and below the Must be aquitards both above and below the

aquifer to stop the water from escaping aquifer to stop the water from escaping

Artesian WellArtesian Well

Karst TopographyKarst Topography

Karst topography- landscapes that have Karst topography- landscapes that have been shaped largely by the dissolving been shaped largely by the dissolving power of groundwaterpower of groundwater Typically have irregular terrain, with many Typically have irregular terrain, with many

depressionsdepressions Sinkholes- depression produced in a region Sinkholes- depression produced in a region

where groundwater has removed soluble rockwhere groundwater has removed soluble rock Form in one of two waysForm in one of two ways

Gradually develop; fairly shallow and have gentle Gradually develop; fairly shallow and have gentle slopesslopes

Form when roof of cavern collapses; steep-sided and Form when roof of cavern collapses; steep-sided and deepdeep

SinkholesSinkholes

Environmental ProblemsEnvironmental Problems Overuse and contamination Overuse and contamination threatens groundwater supplies in threatens groundwater supplies in some areassome areas

Nonrenewable resourcesNonrenewable resources Subsidence- ground level sinksSubsidence- ground level sinks

ContaminationContamination Septic tanks, farm wastes, inadequate or Septic tanks, farm wastes, inadequate or broken sewersbroken sewers Fertilizers, pesticides, highway saltsFertilizers, pesticides, highway salts

CleanupCleanup Abandoning water supplyAbandoning water supply Pumping and treatmentPumping and treatment

SALT WATER SALT WATER INTRUSIONINTRUSION

What’s going on here?What’s going on here? Ever noticed this at Ever noticed this at

the beach?the beach? Man… that shower was Man… that shower was

salty!! salty!! (and the tap water, (and the tap water, too!!!)too!!!)

So… what is this So… what is this caused by again?caused by again? Aquifer depletion!Aquifer depletion!

And what else is And what else is caused by this???caused by this??? Sinkholes!Sinkholes!

ContaminationContamination