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UA / Geology / GEOL 101 / What is stream discharge?

What is stream discharge?

What is stream discharge?

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School: University of Alabama - Tuscaloosa
Department: Geology
Course: Dynamic Earth
Professor: Keene
Term: Spring 2015
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Cost: 50
Name: GEO 101-007 Exam 4 Study Guide
Description: Here is the exam 4 study guide. This study guide includes all pertinent information covered in the book and lecture. This study guide also provides you with the opportunity to quiz yourself on key terms and ideas.
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GEO 101-007 Exam 4 Study Guide


What is stream discharge?



Chapter 14: Streams and Floods: The Geology of Running Water

1. _____ Water Table

2. _____ Stream

3. _____ Channel

4. _____ Flood

5. _____ Headward Erosion

6. _____ Continental Divide

7. _____ Laminar Flow 8. _____ Scouring

9. _____ Breaking and Lifting 10. _____ Abrasion

11. _____ Dissolution  

12. _____ Dissolved Load

A. Occurs when a fluid flows in parallel  layers, with no disruption between layers

B. Running water removes loose fragments  of sediment

C. A trough dug into the ground surface by  flowing water If you want to learn more check out What is operculum?
Don't forget about the age old question of What does say's law say?

D. Larger solid particles (sand, pebbles, or  cobbles) that bounce or roll along stream  floor


What is erosion?



E. Water seeping through rock surrounding  stream channel dissolves certain minerals  and transports these ions down the stream

F. Occurs when a fluid flows in parallel  layers, with no disruption between layers

G. A ribbon of water that flows in a channel

H. Refers to the maximum particle size a  stream can carry

I. The process by which a stream channel  lengthens up its slope as the flow of water  increases

J. Small solid particles (silt or clay size) that  swirl along in the water without settling to  the floor of the channel We also discuss several other topics like What are the three stages of fetal development?

K. The boundary, approximately parallel to  the Earth’s surface, that separates substrate  in which groundwater fills the pores from  substrate in which air fills the pore


How do streams transport sediment?



L. Running water can break clasts of solid  rock off the channel floor or walls, or may  lift clasts of the channel floor

13. _____ Suspended Load 14. _____ Bed Load

15. _____ Stream Competence

16. _____ Stream Capacity  17. _____ Turbulent Flow Draining the Land:

M. A highland separating drainage that  flows into one ocean from drainage that  flows into another

N. Running water containing sand to gravel  size particles acts like sandpaper and grinds  away at the channel floor or walls

O. An event during which the volume of  water in a stream becomes so great that it  covers areas outside the stream’s normal  channel If you want to learn more check out What is love?

P. Running water dissolves soluble minerals  as it passes and carries the minerals away in  solution

Q. Refers to the total quantity of sediment it  can carry (depends on competence and  discharge) We also discuss several other topics like What is body mass index?

• Precipitation (rain, snow, hail) brings water to land surface

• Groundwater springs also bring water to the land surface

• Gravity pulls surface water downhill into a stream channel, which is a trough in the  surrounding substrate

Stream Formation:

1. Precipitation (rain) occurs

2. Sheetwash flows downhill

3. Flowing water digs tiny channels called rills

4. Rills downcut; develop into streamflow

Drainage Network (basin):

• An array of interconnecting stream that together drain an area

• 5 types

o Dendritic

o Rectangular

o Trellis

o Radial

o Parallel

• The geology (rock type) of land surface is the major control over the type of drainage  network that develops

Drainage Divides and Basins:

• A highland or ridge that separates one drainage basin (network) from another

5. I, 6. M, 7. F, 8. B, 9. L, 10. N, 11. P, 12. E, 13. J, 14. D, 15. H, 16. Q, 17. A Answers: 1. K, 2. G, 3. C, 4. O,

GEO 101-007 10/28/15 Permanent vs. Ephemeral Streams

Permanent Streams: 

• Water flows all year

• Bed/floor of channel is at or below  the water table

• Humid or temperate climates o Sufficient rainfall We also discuss several other topics like What are the principles of liberalism?

o Low evaporation

• Discharge varies seasonally  Stream Discharge:

Ephemeral Streams: 

• Do not flow all year

• Bed/floor of channel is above  

the water table

• Dry climates

o Low rainfall

o High evaporation

• Flows mostly during rare  

flash floods

• Discharge = area of the stream times average stream velocity

• Measuring water flow velocity can be difficult

o Not all water flows through a stream/river at the same speed

Erosion:

• Efficiency of erosion is a function of velocity, volume, and sediment content of water o Small volume, slow-moving, clear water

▪ Not efficient at erosion

o Large volume, fast-moving, turbulent, sandy water

▪ Very efficient at erosion

o A lot of erosion can occur during a flood (more energy)

How do streams transport sediment?

• Geologists refer to the total volume of sediment carried by a stream as its sediment load.

Sediment Deposition:

• High energy (fast moving water) = sediment erosion/transportation

• Low energy (slow moving water) = sediment deposition

• Typically, stream/river energy decreases slowly. When this happens, the larger clasts  (pebbles) are deposited first, then medium-size clasts (sand), and finally small clasts  (silt/clay). Sorting occurs

• Fluvial deposits (alluvium) – sediment deposited in a stream channel, along a stream  bank, or on a floodplain

• Point bar – a wedge-shaped deposit of sediment on the inside bank of a meander • Delta – a wedge of sediment formed at a river mouth when the running water of the  stream enters standing water, the current slows, the stream loses competence, and  sediment settles out

Stream gradient:

• The slope of a stream’s channel in the downstream direction

• Longitudinal profile – a cross-section image showing the variation in elevation along  the length of a river

GEO 101-007 10/28/15

Base Level:

• The lowest elevation a stream channel’s floor can reach at a given locality

• Ultimate base level is sea level (sea level can move up and down

o A lake represents a local base level

o A stream “tries” to erode down to base level (slow process)

In general, a stream cuts down into the ground in the headwaters and cuts from side to side near  the mouth

Meander: a snake-like curve along a stream’s course

Alluvial Fan:

• A gently sloping apron of sediment dropped by an ephemeral stream at the base of a  mountain in arid or semi-arid regions

Braided stream:

• A sediment-choked stream consisting of entwined sub-channels

Chapter 15: Restless Realm: Oceans and Coasts

1. _____ Bathymetry

2. _____ Abyssal Plain

3. _____ Seamounts

4. _____ Current

5. _____ Coriolis Effect

6. _____ Gyre

7. _____ Thermohaline Circulation  8. _____ Tidal Reach

A. Low area between waves

B. The bending of the waves as they  approach the shore at an angle

C. As the lithosphere moves away from the  mid-ocean ridge spreading centers it cools  down and sinks, creating a flat section of  ocean floor

D. The elevation difference between sea  level at high tide and low tide

E. Time interval between passage of two  successive crests

F. A well-defined stream of ocean water

G. Hot-spot volcanoes (non-plate boundary  related) that do not rise above sea level

H. Top of the wave

GEO 101-007 10/28/15

9. _____ Crest

10. _____ Trough

11. _____ Base

12. _____ Wave Refraction

13. _____ Fjord

What does crust have to do with oceans?

I. A deep, glacially carved, U-shaped valley  flooded by rising sea level

J. Variation in depth

K. A large, circular flow pattern of ocean  surface currents

L. The rising and sinking of water driven by  contrasts in water density which is due in  turn to differences in temperature and  salinity; this circulation involves both  surface and deep water currents in the ocean

M. The deflection of objects, winds, and  currents on the surface of the Earth owing to  the planets rotation

• Compared to continental crust, oceanic crust is more dense, thinner, and younger • These differences result in the surface of the oceanic crust having a lower elevation than  continental crust

Ocean Floor Features:

Passive Continental Margin:

• Continental shelf (wide)

• Continental slope

• Continental rise

Passive Continental Margin:

• Relatively shallow water

• Relatively flat

Answers: 1. J, 2. C, 3. G, 4. F, 5. M, 6. K, 7. L, 8. D, 9. H, 10. A, 11. E, 12. B, 13. I

Active Continental Margin:

• Continental shelf (narrow)

• Continental slope (steeper)

• Trench

Abyssal Plain

Submarine canyons

Seamounts

Mid ocean ridges

GEO 101-007 10/28/15

Active Continental Margin:

• Deep trenches

• Mariana Trench

Ocean Water and Currents:

• Salinity – the degree of  

concentration of salt in water

Ocean Water Salinity Variation:

• Ocean water salinity variation is a  

function of:

o Water temperature (warm water can hold more salt)

▪ Tropics are generally warmer due to more solar radiation

▪ A large difference in water temperature with depth exists near the tropics ▪ Warm water from tropics is transported toward the poles by currents 

o Addition of freshwater from river runoff, groundwater, ice melt, and direct rain o Evaporation rate at oceans surface

o Ocean currents (fast moving vs. slow)

▪ Surface Currents are caused by interaction between wind and the surface  of water. Only affects the upper few hundred meters of water

▪ Deep Currents are also influenced by wind due to zones of upwelling and  downwelling

Ocean Deep Currents: Rivers in the Sea

• Upwelling- wind pushing water  

away from coast (southern wind)

• Downwelling- wind pushing water  

toward the coast (northern wind)

Wave Action:

• Cause: shear of wind blowing over  

the water surface

• Energy decreases with depth

• Wave morphology:

o Crest

o Through

o Base

Longshore Current and Longshore Drift

o Responsible for sediment transport along coast

GEO 101-007 10/28/15

The Coastal Zone:

• Beach- an accumulation of sediment found along  

landward margin of ocean

Offshore Bars:

• Submerged or partly exposed ridge of sand or  

coarse sediment that is built by waves offshore  

from a beach

• Breaking waves dig into the sand near the  

shore creating trough 

• The excavated sand is deposited either on the  

beach or aside forming sandbar (offshore bar)

Barrier Islands:

• Offshore piles of sane built above sea level  

that is a result of high rate of sediment  

deposition due to wave and tide activity  

Estuaries:

• An inlet in which seawater and river water mix, created when a coastal valley is flooded  because of either rising sea level or land subsidence (sinking)

• Bar-built estuaries

o Form when a shallow lagoon or bay is protected from the ocean by a sand bar or  a barrier island

• Coastal Plain Estuaries

o Formed at the end of the last ice age between 10,000-18,000 years ago. As  glaciers receded and melted, sea levels rose and submerged low-lying river  valleys

Organic Coasts:

• A coast along which living organisms control landforms along the shore • Coastal wetlands (salt marshes and mangroves

• Coral reefs

GEO 101-007 10/28/15 Chapter 16: A Hidden Reserve: Groundwater

1. _____ Groundwater 2. _____ Water Table

3. _____ Unsaturated Zone 4. _____ Saturated Zone

5. _____ Aquitard

6. _____ Aquifer

7. _____ Confined Aquifer

8. _____ Unconfined Aquifer 9. _____ Perched Aquifer 10. _____ Infiltrate

11. _____ Recharge area 12. _____Discharge area

A. Seep down into

B. The region below the water table where  pore space is filled with water

C. A mound of groundwater becomes  trapped above a localized aquitard that lies  above the regional water table

D. Sediment or rock that does not transmit  water easily and therefore retards (slows  down/stops) the motion of water (typically  has both low porosity and permeability)

E. An aquifers that is separated from the  Earth’s surface by an overlying aquitard

F. A location where water enters the ground  and infiltrates down to the water table

G. Water that resides under the surface of  the Earth, mostly in pores and cracks of rock  or sediment

H. A spring that emits water ranging in  temperature from 30-140 degrees C

I. An aquifer that intersects the surface of  the earth

J. The region of the subsurface above the  water table, pore space may contain some  water and some air

K. Sediment or rock that transmits water  easily (has high porosity and permeability)

L. The potential energy available to drive  the flow of a given volume of groundwater  at a location; can be measured as an  elevation above a reference

GEO 101-007 10/28/15

13. _____ Hydraulic Head 14. _____ Oasis

15. _____ Hot spring Karst Landscape:

M. The boundary, approximately parallel to  the Earth’s surface, that separates substrate  in which groundwater fills the pores from  substrate in which air fills the pores

N. A verdant (green with grass, etc.) region  surrounded by desert, occurring at a place  where natural springs provide water to the  surface

O. A location where groundwater flows  back up to the surface, and may emerge at  springs

• A region by underlain by caves in limestone bedrock; the collapse of the cave creates a  landscape of sinkholes separated by higher topography; or of limestone spires separated  by low areas

Porosity and Permeability:

• Porosity – the total volume of empty space (pore space) in a material, usually expressed  as a percentage, pores can become filled with water

• Permeability – the degree to which a material allows fluids to pass through it via an  interconnected network of pores and spaces

Perched Aquifer: a mound of groundwater becomes trapped above a localized aquitard that lies  above the regional water table

Groundwater Flow:

• Gravity and pressure cause groundwater to flow; groundwater  

can flow sideways and even upward

Groundwater Flow:

• Very slow compared to surface water

• Rate can vary from 4 to 500 meters per year (13 to 1640 feet per  

year)

• Rate is a function the slope of the water table (hydraulic head)  

and the permeability of the material through which the  

groundwater is flowing

• Moves at a snail’s pace

Artesian Well:

• A well in which water rises on its own

• Potentiometric surface – the elevation to  

which water in an artesian system would rise  

. O, 13. L, 14. N, 15. H Answers: 1. G, 2. M, 3. J, 4. B, 5. D, 6. K, 7. E, 8. I, 9. C, 10. A, 11. F, 12

GEO 101-007 10/28/15

if unimpeded; where there are flowing artesian wells, the potentiometric surface lies  

above ground

Spring:

• A natural outlet from which groundwater flows onto the ground surface

• Where the ground surface intersects the water table n a discharge area

Various Types of springs:

• Where flowing groundwater collides with a steep, impermeable barrier, and pressure  pushes it up to the ground along the barrier

• Where a perched water table intersects the surface of a hill

• Where downward-percolating water runs into a relatively impermeable layer and  

migrates along the top surface of the layer to a hillslope  

• Where a network of interconnected fractures channels groundwater to the surface of a hill

Hot Spring Rock deposits:

• Travertine- a rock composed of crystalline calcium carbonate formed by chemical  precipitation from groundwater that has seeped out at the ground surface

Groundwater Concerns:

• Change of groundwater flow direction

• Saltwater intrusion

• Ground subsidence

o When intensive irrigation removes groundwater, pore space in an aquifer  

collapses.  

o As a result, the land surface sinks, leading to the formation of ground fissures and  causing houses to crack  

Chapter 18: Amazing Ice: Glaciers and Ice Ages

1. ___I__ Glacier

2. __E___ Sublimation 3. __F___ Melting

4. ___A__ Calving

5. ___J__ Moraine

6. __C___ Lateral Moraine

A. (Breaking off of chunks of ice) B. Sediment deposited at sea by melting

C. A strip of till along the side margins of a  glacier

D. Cobble to boulder size clasts of rock  found within till or random places where the  glacier was once flowing

E. (Evaporation of ice into water vapor) F. (Ice melts and liquid water flows away)

GEO 101-007 10/28/15

7. __G___ Medial Moraine

8. ___H__ Till

9. __D___ Erratics  

10. __B___ Glacial Marine 11. ___K__ Glacial outwash 12. __P___ Loess

13. __M___ Glacial Lake Bed 14. __L___ Varve

15. __R___ Kettle Hole

16. __O___ Drumlin

17. __Q___ Glacial Subsidence

G. A strip of till in the interior of a glacier,  parallel to the flow direction of the glacier,  formed by the lateral moraines of two  merging glaciers

H. Unsorted sediment carried by ice,  deposited beneath, at the side, or at the toe  of a glacier

I. A river or sheet of ice that slowly flows  across the land surface and lasts all year  long (movement caused by gravity)

J. A sediment pile composed of till (glacial  sediment) deposited by a glacier

K. Till from the glacier toe that is  transported (and sorted) by braided streams

L. A pair of thin layers of glacial lake-bed  sediment, one consisting of silt brought in  during the spring floods and the other of  clay deposited during the winter when the  lake’s surface freezes over and the water is  still

M. Fine grained sediments deposited in  glacial lakes; varves are common  

(alternating thin layers of clay and silt)

N. The process by which the surface of a  continent rises back up after an overlying  continental ice sheet melts away and the  

weight of the ice is removed (still happening  today in some areas)

O. A streamlined, elongated hill formed  when a glacier overrides glacial till

P. Silt and clay size sediment transported  away from glacier’s toe and deposited some  distance away from the glacier

Q. The sinking of the surface of a continent  caused by the weight of an overlying glacial  ice sheet

GEO 101-007 10/28/15

18. __N___ Glacial Rebound R. A circular depression in the ground made  when a block of ice calves off the toe of a  

glacier, becomes buried by till, and later  

melts

Louis Agassiz:

• Geologist from Switzerland

• Proposed that places in Europe that had random rocks showing up must have been a  result of a glacier dropping the rocks as it melted

Glacial Erratic:

• Erratic

o A boulder or cobble that was picked up by a glacier and deposited hundreds of  

kilometers away from the outcrop from which it was detached

Ice (frozen water) is a mineral (naturally occurring, inorganic solid, with a definite chemical  composition and regular crystal structure

Layers of Snowfall:

• Layers of snowfall are very much like layers of loose sediment

• With time and pressure (from snow above), snowflakes recrystallize into solid ice

Snow to solid ice:

• Loose snow

• Granular snow

• Firn

• Fine-grained ice

• Coarse-grained ice

• Firn 

o Compacted granular ice (derived from snow) that forms where snow is deeply  

buried; if buried more deeply, firn turns into glacial ice

Formation of Glaciers:

• Three criteria for glacier formation

1) Local climate must be cold enough that winter snow does not melt entirely away  

during the summer

2) There must be sufficient snowfall for a large amount of snow to accumulate

3) Slope of the surface must be gentle enough that the snow does not slide away in  

avalanches  

Types of Glaciers:

• Two categories of glaciers

1) Mountain (alpine) – shape controlled by topography of mountains – flow from  

high to low elevation

I. Cirque

II. Valley

III. Ice caps

IV. Piedmont

N 18. Q, 17. O, 16. R, 15. L, 14. M, 13. P, 12. K, 11. B, 10. D, Answers: 1. I, 2. E, 3. F, 4. A, 5. J, 6. C, 7. G, 8. H, 9.

GEO 101-007 10/28/15

2) Continental – vast ice sheets that cover thousands of square kilometers of  continental crust – today the only exists in Antarctica and Greenland

How exactly do glaciers move?

• Plastic deformation

1) Only occurs below 60 m

2) Grains change shape very slowly as new grains form while old grains disappear • Basal sliding

1) Must be warm enough for water to build up at base of glacier

2) Water along base on glacier acts as a lubricant on which the glacier can move  (water decreases friction)

• The rate of ice movement varies with time and within the glacier (friction slows down  movement where ice contacts rock/sediment)

Crevasse Formation

• A large crack that develops by brittle deformation in the top 60 m of a glacier

Glaciers are similar to bank accounts:

• Deposits = snowfall

• Withdrawals =ablation

• Zone of accumulation

• Equilibrium line

• Zone of ablation

• Terminus (toe)

• Ablation includes:

o Sublimation (evaporation of ice into  

water vapor)

o Melting (ice melts and liquid water flows  

away)

o Calving (breaking off of chunks of ice)

Icebergs:

• Ice is grounded in shallow water, but floats in  

deep water

Sea Ice (also contribute icebergs to ocean)

• Ice formed by the freezing of the surface of the sea

GEO 101-007 10/28/15

Plucking and Abrasion:

• Plucking is chunks of bedrock being  

plucked out by the moving ice  

• Abrasion is chunks of rock that has  

already been plucked up into the  

glacier that move against the bedrock  

as the glacier moves and cause  

abrasions  

Pleistocene Epoch (~2.6 mya to 11,000 ya)

• Laurentide Ice Sheet – an ice sheet  

that spread over northeastern Canada  

during the Pleistocene ice age(s)

Glaciation (glacial period):

• A portion of an ice age during which huge glaciers grew and covered substantial areas of  the continents  

Interglacial – a period of time between two glaciations

Holocene – a period of geologic time since the last ice glaciation

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