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UNIT 7 RIVERS AND STREAMS (Chapter 12 Running Water) Study Guide

(Revised 7/16)

UNIT 7 HOMEWORK worth 10 points

WEB HIT: WORK ON RIVER RESEARCH PAPER HOMEWORK – see page 11/12

For any Unit Web Hits, go to the “DMC HOME” website; in Search box –type “Geology”, select “Vernon

Kramer”, scroll down to GEOL 1303, select “Syllabus”, select “Web Hit Links”, click on icon of interest for web sites

OR: go to DMC Home website, select “Degrees, Certificates, Courses”, scroll down to Natural Sciences and select

“Geology”, select “Faculty Listings”, select “Walter Vernon Kramer”, find “Geol 1303”, select “Syllabus”, and there

you can find the” web hit links” click on icon of interest for web sites

[IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED)

SEE PAGES 12 & 13 FOR RIVER RESEARCH PAPER

General

- Landscapes without a hydrologic system will change very little over time. For example, the Moon

surface has changed very little over the last billion years.

Erosion: the removal of rocks and soil by ground water, running water, waves, glaciers or wind

- There are many large “river channels” that have deeply cut the surface of Mars. Surprisingly, the

water that cut these channels did not come from rainfall, but from “groundwater”.

- Recent satellite pictures show channels that were carved by rivers of liquid methane on the Saturn

moon of Titan. Thus we know of river channels on two planets and one moon.

- River and stream valleys dominate the appearance of the Earth’s surface as impact craters dominate

the lunar surface.

Erosion

River erosion: surface removal and transport of rocks and soils by flowing water

- River and stream valleys dominate the appearance of the Earth’s surface as impact craters dominate

the lunar surface.

- There are more than 11,240 rivers in Texas alone that cause erosion and shape our landscape!

Truth is stranger than fiction, but it is because fiction is obliged to stick to possibilities; truth isn’t.

Mark Twain

Landforms Can be Created by Rivers

- Landforms (hills and valleys) shaped by running water (rivers) produce the most significant erosional

landforms on Earth. The Grand Canyon is a prime example of this.

- River networks can even dominate landscapes in both humid and desert environments.

Water Supply

- Rivers and lakes provide 50% - 60% of the US public water supply, even though rivers and lakes

contain about 2%-3% of Earth’s water.

- Some have suggested that the creation of millions of large and small lakes has prevented a rise in sea

level. These lakes are preventing the water from returning to the oceans.

Basic River Components

- What is a river? Any large body of water that flows downhill in a well-defined channel (water that

flows under gravity to progressively lower levels).

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Headwaters: The source area for the beginning point of rivers and streams.

River bed or river channel: An elongated depression or passageway containing (or had contained)

flowing water.

River banks: The ground bordering both sides of a river that serves to confine the water to the natural

channel during its normal course of water flow.

Tributary: A stream or smaller river that joins a larger river. This larger river can be a tributary if it

joins an even larger river.

River mouth: The final point of water discharge for a river (usually where a delta forms).

River system: a river channel and all its tributaries

GENERAL CHARACTERISTICS OF A RIVER SYSTEM

(Remember the Gonsalves painting that compares river drainage systems to a large tree with many

branches)

- Again: a tributary is a smaller river that joins a larger river

1) The number of tributaries decreases downstream. (Like the number of branches that decrease as you

go down from the very top of the tree)

2) Tributary length increases downstream. (Individual tree branches get longer as you go down the top

of the tree.)

3) The river gradient (steepness) generally decreases downstream. (Water runs downhill.)

4) River channels are wider and deeper downstream. (Just like tree branches get bigger as you go

down from the top of the tree.)

5) Valley size is proportional to river size and increases downstream. Generally - larger the river, the

larger the river valley.

The tragedy of life doesn't lie in not reaching your goal. The tragedy lies in having no goals to

reach. Benjamin Mays

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Reported “Speeds of River Flow

1. River Discharge velocity: The “calculated” volume of water of a river as it moves past a specified

line per unit of time (i.e. 4,000 cubic feet of water/second).

- A common number reported by TV news reporters during times of floods.

2. River water velocity (in the US commonly reported as feet/sec) within a river channel

3. The steeper the river gradient (from high elevation to low elevation), the faster the water will flow

The surest way not to fail is to determine to succeed.

Richard B. Sheridan

Relative Water Speeds of Various Types of Channels

Straight River Channel verses Curved River Channels Velocities: In any channel, moving water speed

is affected by friction on the sides and the bottom of the channel

- Even the surface air presents a weak friction force on the river’s surface to slow down the water

movement.

- Straight river channel:

a) Slower water velocity rate: is found along the river bottom, along river edges (banks) and

along the top of the water (air surface)

b) The fastest water velocity rate is found at the center of the river channel, slightly below the

surface;

water velocities in straight and curved channels; darker is faster - Curved river channel: When the water of a river enters a curved river channel, centrifugal forces take

over and the water mass begins to rotate.

a) Slower water velocity rates are found on the inside of a curve; here sand will be deposited as

sand bars. This also presents a shallow river area that is safer to play and wade.

b) Faster water velocity rates are found toward the outside of curves; here erosion occurs by

undercutting the banks (cut-banks). This is a dangerous area to swim because the water speed

could sweep you under the eroding river banks.

Channel Components Along the River

- Most natural rivers do not flow very far in a straight line; river channels are noted by their curved-

shaped patterns. Whenever you see very straight, long river channel – it was probably man who

prepared these channels.

Meanders: Broad, looping bends in a river that can form a sinuous (winding) pattern

Cut banks: A river bank eroded on the outside curve of a river channel meander

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Point bars: A crescent-shaped accumulation of sand and gravel deposited on the inside of a river

channel meander

Natural levees: A broad, low embankment built up along the banks of a river channel during floods

Oxbow lakes: A temporary lake formed in the channel of an abandoned meandering river or stream

- The creation of oxbow lakes can cause land ownership problems if the title uses the river channel as a

property boundary instead of using “surveyed points”. The formation of oxbow lakes can also create

problems for state and international boundaries that use only the river bank for a boundary instead of

surveyed points.

River sketch: cut banks, point bars, meanders, oxbow lakes

We must be vigilant in our quest to prevent the “death of consequences” such as:

-You find it acceptable to fail a class and don’t feel that you wasted your time and money

River Systems and Drainage Basins

River system consists of a main channel and all its tributaries – all within a single drainage basin.

- Any water (precipitation as rain or snow) that falls within a certain drainage basin is confined to that

river system or drainage basin.

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Drainage basins of Texas

Drainage Divides

Drainage Divide: A boundary that separates one drainage basin (river system) from another

- Water from rainfall within one drainage basin (watershed) will not enter another drainage basin

(watershed).

US Continental Divide

Continental Divide

Continental Divide: The main “divide” (an imaginary line) of any continent that separates rivers that

empty into different ocean basins

US Continental Divide: The US continental divide runs along the crest of the Rocky Mts. from Canada

to Mexico, and divides the US into two large drainage basins.

- The US Continental Divide separates the rivers; one set of rivers drains water westward to the Pacific

Ocean and the other set of rivers drains water to the east and southward to the GOM and the Atlantic

Ocean.

River Systems - General

River Systems may be divided into three subsystems with gradational boundaries:

1. Erosion Subsystem - mostly eroding sediments at headwaters of rivers

2. Transporting Subsystem – mostly transporting eroded sediments along the rivers

3. Deposition Subsystem – mostly deposition of sediments at the end of a river system

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1. EROSION SUBSYSTEM – rivers as agents of erosion of rocks and sediments

- A network of headwater tributaries that funnels water and eroded sediments into a larger channel

- River systems commonly form a dendritic (tree-like) drainage patterns that extend upslope to the

eroding edge of the drainage basin.

- We have found dendritic drainage patterns on Mars and the moon Titan

- Dendritic channels and valleys generally have V-shaped valleys.

- There are other types of drainage patterns, but these patterns are not very extensive.

- Typically, headwaters have clearer stream or river waters like we find in the upper Frio River.

- River erosion processes on Earth operate at a faster pace in areas that have large, major river systems

(more water available).

- Erosion will proceed at a much slower pace within areas with minor river systems such as within

deserts (less water available).

Rivers – Erosional Processes – Changing Landscape

- There are three processes that a river system uses to erode and change the landscape

A. Removal of regolith (regolith is loose soil and rock on top of solid rock)

- Regolith can be washed or can slide into a river channel and can be removed from the area

B. Downcutting of the river channel (which broadens and deepens the river valley)

C. Headward erosion uses several processes to expands the drainage basin

A. Removal of Regolith

- The loose regolith will be washed down slope (hydraulic action) and transported down slope into the

river channels.

B. Downcutting of River Channels by Abrasion

Abrasion: In swift moving water, colliding individual rocks and sand will grind out of the bottom and

sides of the river channel

- In swift moving rivers, you can often “hear” the noise made by the grinding action

Down-cutting of river channels by abrasion occurs mostly during floods results in deeper channels

Incised channel – river channel cut into solid rocks (which form canyons)

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Pothole: Cone-shaped hole or depression formed in a river bed by swirling and grinding action of

individual rocks and gravel.

- These resemble grinding bowls produced by earlier Native Americans.

C. Headward Erosion

Headward Erosion - Upriver Migration of Waterfalls

- Erosion and down-cutting of waterfall ledges can cause these rocky ledges to locally collapse.

This results in a new waterfall ledge.

With this process, we can witness the head-ward (upriver) migration of a waterfall over time, as

exemplified by the ever-moving location of Niagara Falls.

Headward Erosion – Extending Drainage Basin

- Erosion that can extend the reach of a drainage basin

Headward Erosion – River Piracy

Stream Piracy: The diversion of the waters of one stream into another stream (modifies and

changes the drainage basin of more than one river).

- The Pecos River system of West Texas provides a good example of stream or river piracy. As

the Pecos River eroded “head-ward”, it encountered other river channels. Because the Pecos

River channel had a lower elevation than the river it encountered, the captured channel water was

diverted into the Pecos.

Then 3-D Presentation of Eroding Canyons

We must be vigilant in our quest to prevent the “death of consequences”, such as:

-You take money from grants, parents, scholarships and feel it is acceptable to earn less than an A

and it is acceptable to later quit your education

2. TRANSPORTING SUBSYSTEM - rivers as agents for transporting rocks and sediments

- River channels through which water and sediment flows from the eroding area toward an ocean or a

basin.

- Depending upon sediment size and location, it may take thousands of years or longer to move from

its eroded site to a transporting river

- Rivers associated with transporting systems generally have U-shaped valleys.

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- Erosion and deposition both occur but are generally balanced in a transporting subsystem.

Sediment Load: rocks and soil, etc. that is carried along by the water movement

A) Suspended load involves fine particles (such as mud) carried at same rate as the water

velocity. This load represents the largest fraction of transported sediment that will be

deposited within oceans, lakes, or basins.

B) Bed load represents coarse particles (such as sand and gravel) that is moved along the river

bed by rolling, etc.; the water velocity controls the grain size of the bed load; during floods

bed loads can represent 50% of the total sediment load

C) Dissolved load: dissolved minerals, acids, ions, gas, and pollutants from areas of heavy

vegetation, shale and igneous rocks; in jungles and swamps is represented by dark-colored

river waters FYI: usually involves 4 cations [Ca+2, Na+1, Mg+2, K+1] and 3 anions [HCO3-1,

SO4-1, Cl-1].

Dams Affecting Sediment Transportation

- Dams also can severely impact river systems and people; sometimes in a very negative way by

upsetting biologic “cycles” and sediment “cycles” that prevent sediment from maintaining and

expanding deltas.

3. DEPOSITIONAL SUBSYSTEM - rivers as agents for depositing rocks and sediments - The dispersion of the sediments from the river is a deposition system – i.e. – the sediment load is

dropped to fill in a basin, which is generally an ocean basin.

- Rivers with the largest active deposition of sediments into the oceans: Ganges River, Amazon River,

Mississippi River.

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Deposition within an Erosion Subsystem (filling a non-ocean basin)

- Not all sediment reaches an oceanic basin

Alluvial fan: Accumulation of sediment in a dry basin. The sediment will form fan-shaped deposits

especially in dry, mountainous areas.

Alluvial fan sketch

Deposition in the Transporting Subsystem (filling a non-ocean basin)

Alluvium: Any sediment deposited by the recent action of rivers (most sediment is deposited by

floods)

Floodplain: The flat, occasionally flooded area that borders a river or stream (filled with alluvium)

The Depositional Subsystem

Delta: a low, nearly flat alluvial area near the mouth of a river, formed by sudden drop in water

velocity and dumping of its sediment load

- There are many types of delta classifications

- The Mississippi River delta is classified as a “bird-foot delta” because of its unique shape

- Large swamps are an integral part of most deltas.

Delta Creation

Deltas evolve by 2 mechanisms: 1) Distributary Channels, 2) Avulsion

1. Distributary Channel: numerous stream channels in a delta that disperse water and sediment

2. Avulsion: This represents a shift in the main course of a river to a totally new and different

channel that results in forming a new delta in a new location.

Flooding

- Floodplain stages:

1) Normal stage: river water level that is below its bank or natural levee

2) Bank-full stage: river water level that stays about even with its banks or levee

3) Flood stage: the water in the river that overflows its river banks and the water submerges the

local area (flooding)

We must be vigilant in our quest to prevent the “death of consequences” such as:

-You convince yourself that it is ok to fail exams and that you don’t have to change your study

methods

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Floods

Floods: Rivers overflowing their natural levee. Floods are not a rare event but a seasonal occurrence.

- Floods have possibly been the cause of the greatest “natural” loss of human life in recorded history.

Flash Flood: A local and sudden flood of short duration caused by a local large downburst of rain.

Flash floods often occur in valleys in a semi-arid regions and hilly terrain but can also occur in cities

(because of all of the pavement and poor drainage planning). These floods can wash vehicles and

people downstream or flood roads and streets and underpasses.

Some River Generalities

- In Texas, any stream bed wider than 30 feet is public property, regardless if it has flowing water or is

a dry bed. These stream beds are legally navigable streams.

- In January2004, it became illegal in Texas to drive off road vehicles in river beds.

- Nueces Drainage Basin includes the Nueces River, Frio River, Atascosa River and many smaller

tributaries.

- There are two large reservoirs, created by dams, within the Nueces watershed: Choke Canyon Lake

(near Three Rivers) and Lake Corpus Christi (near Mathis).

- Lake Texana is located near Edna, TX on the Navidad River. This reservoir provides almost 50% of

the drinking water for Corpus Christi via the 101 mile long Mary Rhodes pipeline.

ALWAYS ON EXAM - There is a salt water barrier dam on the Nueces River at Labonte Park to prevent high tides (salt

water) from entering the upper reaches of the river system and contaminating our water supply.

The squeaky axle gets the grease

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LOCAL RIVERS TEAM DISCOVERY PROJECT FOR UNIT #7 RIVER SYSTEMS

(Designed for Written Communication Skills and Critical Thinking Skills

Guadalupe, San Antonio, Nueces River Basins Frio River Basin (Tributary of Nueces

River)

Purpose: Prepare a “tri-folded travel brochure or tour guide” for your selected “local” Texas river

ITEM #1; Each team member must select one of the four (4) possible choices of rivers for a brochure

River Choices: (Only one “river” each student in a group of 4 – thus each group will have 4 different

rivers)

1) Guadalupe River;

2) San Antonio River (tributary to the Guadalupe River);

3) Nueces River;

4) Frio River (tributary to Nueces River)

References to List: at least 3 (list only references used) and include your name at END of brochure

You can create a black and white or colored TRAVEL BROCHURE with a map of the river and

interesting pictures of river features. Do not copy a brochure from the internet – called

plagiarism, as I will check! Get your pictures from the internet or use your own pictures.

Some features that you may want to point out could include: (up to you which to use):

a) location source of the river

b) location of estuary into which it empties or main river that intercepts this river (if a tributary)

c) length of the river;

d) maybe list a few major towns along its banks;

e) maybe mention dams or lakes along its course;

f) maybe list names of public State parks and a few public campgrounds along its course;

g) maybe popular sports/recreation centers along its course;

h) maybe special species of fish, animals, plants found along its course;

i) maybe any special information that you found interesting about the river

For your team members: Print out completed copies for each one; REMEMBER THE DUE DATE

See following page 12 for grading rubrics

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GRADING RUBRICS for RIVER RESEARCH PROJECT

COMMUNICATIONS SKILLS-(for RIVER RESEARCH PROJECT)

Rubric for Aspect 1 – Written communication:

6 points – Exceeds

Expectations

5 points – Meets

Expectations

2 points – Below

Expectations

0 – Not

Acceptable

Message

appropriate for

purpose,

Exceptionally

appropriate/effective

for purpose, occasion

Content adequately

appropriate/effective

for purpose,

Content inadequate

for purpose,

Failed to meet

assignment

purpose

Clear &

coherent

organizational

structure

Exceptionally clear

organization pattern;

easily followed

Reasonably

organized; logical

progression of ideas

Rambled;

organization difficult

to follow; lacked

unity

Repetitive

ideas;

impossible to

follow

Main points

fully supported

( 10 examples,

figures, etc.)

Multiple examples,

memorable details

that support central

theme

Adequate details

and 10 examples,

to support central

theme

Lacked adequate

number of examples

to support central

theme

No details

provided or

failed to support

central theme

Referenced

web sites

More than 3 websites Referenced 3 websites Referenced 2

websites

No websites

referenced or

listed references

they did not use

CRITICAL THINKING SKILLS (for RIVER RESEARCH PROJECT)

Rubric for Aspect 6 -

2 – Exceeds 1 – Meets 0 – Below 0 – Not

Acceptable

Aspect 6 Synthesis:

Integrate/organize

information in its

functional context

Information is

clearly

organized &

integrated into a

functional

context

Some information

is organized and

integrated into a

functional context

Information is

organized but not

integrated into a

functional context

Ideas are

disjointed and

presented without

a contextual

framework

If you use Microsoft Office and Word:

Open Word Document

Click File

Click New

Depending upon version of Office:

Select Brochures and Booklets

or Tri-fold brochure (remember to use front and back sides)