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55 Cards in this Set

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Types of motion (mass wasting)
-falling
-flowing
-sliding
Mass wasting
the downslope movement of Earth's materials due to gravity
Factors that cause mass wasting
-rainfall
-construction
-undercutting by waves
-type of material that makes up ground
-angle of repose
Which process of mass wasting causes most economic damage?
surface creep
slump
when Earth's materials move along a curved surface
Processes of Mass wasting
-rock fall
-rock avalanche
-landslide
-slump
-earthflow
-mudflow
-surface creep
-solifluction
Which processes of mass wasting cause the most damage?
surface creep and solifluction
Human activities that enhance mass wasting
-increased runoff leads to slumping in river bends
-building roads, retaining walls
-lawn (watering, spectic tanks)
-vegetation (limits how hard water falls, roots hold soil in place, slows runoff process, helps soil process)
-unnatural drainage
-urban areas
What does running water do?
-erode
-sculpt the land
-build up landscapes
angle of repose
steepest angle at which material remains stable
rockslides
when blocks of bedrock break loose and slide down a slope
debris slide
when involved material is largly unconsolidated
Where do earthflows form?
on hillsides in humid areas
Creep
involves gradual downhill movement of soil and regolith
solifluction
when soil is saturated with water and the soggy mass flows downslope
Permafrost
permanently frozen ground that occurs in association with Earth's harsh tundra
Sheet flow
broad, thin sheets across the ground
runoff
when the rate of rainfall is greater than the land's ability to absorb it, additional water flows over the surface into lakes and streams
discharge
total amount of water flowing past a certain point (Q= width x depth x velocity)
erosion
lifting of particles by turbulant flow
stream capacity
total amount of sediment
stream competence
maximum sized sediment in a stream
What is the most common destructive geologic hazard?
FLOODS!!!
What causes flooding?
-more rainfall, snow melt
-natural part of the process
How often do rivers flood?
About every two and a half years
Where are flash floods most common?
In deserts
How does urbanization affect rivers?
1. decrease in lagtime
2. decreases infiltration
3.increases runnoff
4. reduces vegetation
Flood Control measures
- construct dams
-levees
-dikes
-straighten channels
- fill in wetlands
-riprap
laminar flow
water particles move steadily downstream without mixing
Turbulant Flow
water moves in erratic fashion, swirling
Factors in the Velocity of a river
-gradient
-shape, size, and roughness
-discharge
Gradient
slope of stream
longitudinal Profile
cross section view of a river
base level
downward limit to stream erosion
graded stream
correct slope etc. necessary to maintain just velocity
Oxbow Lake
A curved lake produced when a stream cuts off a meander.
Point Bar
A crescent-shaped accumulation of sand and gravel deposited on the inside of a meander.
Cut Bank
the area of active erosion on the outside of a meander
levees
a dam along the river to force water into a channel (can be natural or artificial)
Three Ways Streams Transport Things
1. solution
2. suspension
3.bedload (bottom of channel)
Settling Velocity
speed at which a particle falls through a still liquid
Mouth
point downstream where it empties into another body of water
bars
coarser components of a stream's laod
meanders
when streams form in a series of bends
floodplain
part of a valley that is inundated during a flood
Alluvial Fan
forms when a high gradient stream leaves a narrow valley in a mountinous terrian and comes out suddnely onto a broad blat plain
Delta
forms when a stream enters a lake or an ocean
distributaries
smaller channels it is divided into
What are some sources of pollution?
runoff
salts
Dams
-try to limit flooding
-source of hydtroelectric power
-affects the eco system
-organisms need annual rise in water
causes for pollution in sreams (urban areas)
1. excess sediment runoff
2. road runoff
3. trash, garbage from storm sewers
4. lawn chemicals
5. pathogens
6. agricultural runoff
7. stream pollution
Sustainable Remedies For Flood Management
- better floodplain management
-space for natural wetlands
-land use planning
-building restrictions
Remedies For Pollution
-restrictions on use of yard chemicals
-restrictions on use and application of agricultural chemicals
-pet waste
Thalwag
region of maximal flow velocity
riprap
-rock or other material used to stabalize the shore