Geological Hazards Final Flashcards

1
Q

Why do people choose to live near rivers?

A

Fertile soil

Transportation

Food source (fish)

Trade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the dangers of rivers?

A

Susceptible to flash flooding

Fast flowing water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the ‘hydrologic cycle’ and how can it be altered?

A

The natural cycle that circulates water throughout the environment to maintain an overall balance between water in the air, on the surface and in the ground.

Human activities that can alter the hydrologic cycle include:

Agriculture

Industry

Alteration of the chemical composition of the atmosphere

Construction of dams

Deforestation and afforestation

Removal of groundwater from wells

Water abstraction from rivers

Urbanization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What affects stream flow?

A

Weather

Snow accumulation and melting

Rainfall and snowmelt

Evaporation

Water use by plants

Vegetation

Subsurface water flows

Water withdrawal for irrigation and municipal water needs

Diversion for hydropower generation

Urbanization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What causes streams to either erode or deposite sediment?

A

Adequate stream flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do people mitigate against flooding dangers?

A

Levees

Dams

Channel straighening

Inundation maps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Transpiration (hydrologic cycle)

A

Water inside of plants in transferred from the plant to the atmosphere as water vapor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Condensation (hydrologic cycle)

A

Vapor to liquid

Forms clouds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Precipitation (hydrologic cycle)

A

Rain or snow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Evaporation (hydrologic cycle)

A

Occurs when the physical state of water is changed froma liquid to a gaseous state.

Water comes from lakes or oceans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Run-off (hydrologic cycle)

A

Rivers or streams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Infiltration (hydrologic cycle)

A

The physical process involving movement of water through the boundary area where the atmosphere interfaces with the soil. The surface phenomenon is governed by soil surface conditions. Water transfer is related to the porosity of the soil ad the permeability of the soil profile. Water that is infiltrated and stored in the soil can also become the water that later becomes subsurface runoff.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Percolation (hydrologic cycle)

A

The movement of water through the soil, and its layers, by gravity and capillary forces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Stream profile: head, mouth, gradient

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Discharge

A

The volume of water flowing through a channel in one second.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Drainage area

A

Drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody such as a river, lake, reservoir, estuary, wetland, sea, or ocean.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Local base level

A

Where a stream’s gradient temporarily approaches or reaches zero before increasing again.

Can be a lake or reservoir or a layer of rock that is highly resistant to the stream’s erosive force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Ultimate base level

A

All rivers and streams erode toward sea level, which is also known as the “ultimate base level.”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Capacity

A

The total amount of load that the stream can move.

Controlled largely by discharge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Competence

A

Measures the largest particles that the stream can transport.

Controlled largely by velocity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Hydrosphere

A

Water

  • Oceans
  • Lakes
  • Rivers
  • Groundwater
  • Ice
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What percentage of the hydrosphere is fresh water?

A

2.8%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Drainage systems

A

Defined by topography

Streams and mass wasting influencing topography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Stream processes (x3)

A

Sediment production

Sediment transport

Sediment deposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Stream Morphology
Tributary (head) Trunk * Anastomosing streams * Meandering streams * Straight streams * Braided streams Distributary (mouth)
26
Sinuosity
Is a ratio expressing the amount of curvature along a stream.
27
Straight Streams
A single straight channel without sediment bars and with low sinuosity.
28
Braided Streams
Relatively straight channels carrying latge amounts of sediment typically found in mountainous areas.
29
Anastomosing
A river with several separate channels which divide and join along the river.
30
Meandering River
Have many bends which change the shape of the river through time by erosion on one bank and deposition on another. High sinuosity
31
Meandering river: cut bank and point bar
32
Floodplain
An area of land between or beyond a stream which receives water when the river is at flood stage.
33
Terraces
Abandoned floodplains that formed when a river flowed at a higher level than it does today. Old floodplains that are cut into by the current stream.
34
Deltas
A discrete shoreline protuberance formed at a point where a river enters an ocean or other body of water. The distributary portion of a river with no set morphology.
35
3 Types of Deltas
Stream dominated (Yukon River, Nile River) Tide dominated (Amazon River) Wave dominated (Rhone River)
36
Natural Levees
Deposition of coarse sediment near the river channel when the river is in flood.
37
3 Types of Sediment Load
Bed load Suspended load Dissolved load
38
Sediment Load: Bed Load
Large material that moves along the bottom of a stream channel (rolling and saltation). Material size: sand, gravel, and boulders
39
Sediment Load: Dissolved Load
Dissolved inorganic and organic material present in the water column. Salts and organic compounds: * Halite * Silvite * Pesticides * Fertilizers
40
Flood
When the discharge of a stream becomes so great that it exceeds the capacity of its channel and overflows. Too much water in the stream channel. Events are often described as probability floods.
41
4 Types of Floods
Flash floods Regional floods Jokulhlaup Dam-failure floods
42
Flood Types: Flash Floods
Occur with little warning, produce rapid rise in water level and may have very high discharge. Common in mountainous, desert, and urban areas. Localized devastation.
43
Flood Types: Regional Floods
Seasonal floods caused by snow melts and spring rain. Common in relatively flat aras where rivers join. Regional devastation
44
Flood Types: Jokulhlaup
Glacial outwash flood Occur with little warning when a volcano erupts under a large mass of ice or water breaches an ice dam. Relatively uncommon Regional devastation
45
Flood Types: Dam Failure Floods
May occur with little warning process occurs by failure of a dam or levee designed to retain water. Relatively uncommon Local devastation
46
Mitigation Methods for Flooding
Levees Dams Channel straightening Inundation maps
47
Mitigation Methods: Levees
High mound of sediment placed parallel to a channel to prevent flooding.
48
Mitigation Methods: Dams
Dam types by use: * storage, * diversion, * detention Dam types by materials: * Earthfall * Rockfill * Steel * Wood * Concrete
49
Mitigation Methods: Channel Straightening
A process were-by meander bends are removed from a channel in order to increase the discharge. This leads to increased erosion and increased river gradients.
50
4 Drawbacks to Flooding
Loss of property Loss of infrastructure Loss of life Toxic waste in water * Sewage * Chemicals * Other waste
51
Benefits of Flooding
Fertile soil Healthy wetland ecosystem * Increased biodiversity * Increased water quality
52
Significant Floods (3)
California Flood (1861-1862) ARkStorm Model Big Thompson Flood 1976
53
California Flood of 1891-1862
Started December 24th 1861 Raining lasted 45 days Creation of inland sea * Area flooded * 480km (300mi)long * 32km (20mi) wide State government moved to San Francisco and stayed for 18 months Deaths unknown Property damage unknown
54
Big Thompson Flood, Colorado 1976
Peak discharge 3.8 x higher than 100 year flood. Low probability flood ~12.5 " of rain in 4 hours 1/3rd of the drainage basin 15 mph Crest of the flood ~19' Exceeded previous record by 10' 139 people died
55
Oxbow lakes
A U-shaped body of water formed when a wide meander from the main stem of a river is cut off to create a lake.
56
Energy for geohazards
Hurricanes, thunderstorms, tornadoes, etc. driven by the SUN's energy.
57
Atmosphere
Made of gas: Nitrogen, Oxygen, Argon, Carbon Dioxide Gets thinner Separated into layers: * Exosphere (gas escapes to space) * Thermosphere (very small amounts of gas, Aurora) * Mesosphere (small amounts of gas, slow meteors down) * Stratosphere (ozone created, NO convection) * Troposphere (all weather happens here) Layers are defined by: thermal charactaristics, density, composition, and movement
58
Redistribution of heat: conveciton cells
Convection of air in the troposphere Influences where wet and dry areas are
59
Redistribution of heat: jet stream
Found near temperature gradients Flow west to east Follow the sun
60
Redistribution of heat: Oceans
Surface current driven by wind Deep ocean currents driven by density
61
Ocean Circulation
Antarctica is isolated from mid-latitude from mid-latitude heat transfer (Antarctic Circumpolar Current) Greenland is not insulated from mid-latitude heat transfer (Gulf Stream/ Norwegian)
62
Temperature
Heat is provided by the sun Changes with altitude (3-5 degrees F/1,000') Land heats and cools quickly Water heats and cools slowly
63
Humidity
Measure of how much water vapor the air contains Warm air holds more water than cool air
64
Relative humidity
The relationship between how much moisture is in the air versus how much it is capable of holding. 50% relative humidity = air is half full \>100% relative humidity = rain
65
Dew Point
Is the temperature to which the air must be cooled to reach saturation High dew points indicate very moist air Low dew points indicate very dry air
66
Temperature and humidity
Changes laterally Control air pressure
67
Air pressure
Amount of pressure exerted by the atmosphere
68
High air pressure zones: diverging air
As the air spreads away, cool air from above must sink to replace it and warms Warm air can hold more water vapor, which means that clouds will tend to evaporate Why fair weather is often associated with high pressure
69
Low air pressure zones: converging winds
Air forced to rise and then cool Cold air holds less water vapor so some condenses, forming clouds and precipitation Why there is often inclement weather near low pressure areas
70
Wind
Wind follows pressure gradient The steeper the gradient the stronger the wind Acted on by gravity, Coriolis effect, friction, and centrifugal forces
71
Coriolis Effect as it applies to weather
Leads to deflection of moving air masses
72
5 Types of Weather Fronts
Cold front Warm front Stationary front Occluded front Trough
73
Cold Front
Dense cold air displaces warm moist air Can form thunderstorms
74
Warm Front
Warm moist air displaces dense cold air
75
Stationary Front
A front between warm and cold air mases that is moving very slowly or not at all.
76
Occluded Front
A composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front.
77
Trough
An elongated area of relatively low atmospheric pressure
78
Where do storms form?
At the boundaries between fronts
79
Clouds
High-level clouds (12km-5km) Mid-level clouds (5km-2km) Low-level clouds (2km-okm)
80
Warm Problems (x5)
Sever thunderstorms Lightning Torrential downpours Tornadoes Hurricanes
81
Cold Problems (x4)
Blizzards Windchill Frostbite Hypothermia
82
Tornado key points (x4)
Surface geohazards, related to the sun (ultimately) Largely a US phenomenon (spring and summer) Sometimes funnel is not visable These days, much easier to predict and get to safety (Doppler Radar)
83
Where do tornadoes come from?
Form at trailing end of thunderstorms within warm, moist air in front of eastward moving cold fronts Can also form in front of hot, dry air flowing from the west And where air is sweeping up mountains
84
Tornado factoids
In an average year, * ~800 tornadoes * ~80 deaths * ~1500 injuries Wind speeds over 250 mph Can travel up to 219 miles (typically shorter ~50miles) Damage over 1 mile wide Average forward speed of 30mph * Can be stationary * Top speed 70mph
85
Fujuta Scale
F-0 (light damage) F-1 (moderate damage) F-2 (considerable damage) F-3 (severe damage) F-4 (devastating damage) F-5 (incredible damage) Not merely based on wind speed Takes kinto accound damage using set of 28 "damage indicators" Also looks at "degree of damage"
86
3 Other words for hurricanes
Typhoons Cyclones "Big wind"
87
What are hurricanes?
Is a large, warm-core, low-pressure storm system over tropical or subtropical waters with water temperatures of at least 25 degrees C * Counterclockwise in N hemisphere, clockwise in S hemisphere Wind sppeds of \> 120kph, can exceed 260kph
88
How do hurricanes form?
Begin over warm seawater (at least 25 degrees C), typically b/t 5-20 degrees latitude Air rises due to localized heating, causes condensation, and formation of towering convective "chimneys" Warm, moist air spreads out at top "chimney" Rising warm air expands, cools, and releases latent heat Rise of air in eye wall pulls more moist air into center of the storm from low elevations Coriolis forces initiate rotation in rising air with the highest winds and lowest pressures focusing toward the core of the storm
89
Hurricane rotation
The eye of the storm is generally 20-50km in diameter * Wind drops from high speeds to low speeds at wind "wall" Whole storm may be 160 to \>800km in diameter Follows prevailing winds, traveling at ~25kph
90
Features of hurricanes
Defined as a hurricane when sustained wind speeds reach 74mph (119kph) Always move toward the west and spin about the eye Need high humidity, light wind, and warm sea surface temperatures
91
Hurricane season
The Atlantic: begins June 1st and ends November 25th The Eastern Pacific: begins May 15th and also ends November 30th
92
Where do hurricanes come from?
Often begin in warm waters off the west coast of Africa, then move westward across Atlantic with trade winds Warm, pick up wind speed and energy, and often develop into hurricanes before they reach Americas Generally track west, northwest, and then north, either off the southeast US or sometimes onto continent
93
Storm classifications (4)
Tropical depression Tropical storm Hurricane Major hurricane
94
Tropical depression (storm classification)
A tropical cyclone with maximim sustained winds of 38mph (33 knots) or less.
95
Tropical storm (storm classification)
A tropical cyclone with maximum sustained winds 39-73mph (34-63 knotts)
96
Hurricane (storm classification)
A tropical cyclone with maximum sustained winds of 74mph (64 knotts) or higher
97
Major hurricane (storm classification)
A tropical cyclone with maximum sustained winds of 111mph (96 knotts) or higher, corresponding to a Category 3, 4, or 5 on the Saffir-Simpson Hurricane Wind Scale
98
Hurricane factoids
80-90 tropical storms each year 45 hurricanes each year 6 named hurricanes per year in Atlantic Ocean and gulf of Mexico More than 44 million people live in coastal areas in the US susceptible to these storms * Gulf Coast and southern Atlantic coasts * ~15% of total population
99
1900 Galveston Hurricane
September 8th Category 4 hurricane Barometric pressure fell to 28.55 in of Hg Winds estimated at 140mph Storm surge of 15.7' Deadliest in US history (estimated minimum death toll of 6,000, likely 8,000-12,000
100
2005 Hurricane Katrina
Category 3 Barometric pressure of 902 mb 125 mph sustained wind Though not the strongest, one of the costliest and deadliest (over $100 billion in damages, 1,836 dead) Category 3 storm hit New Orleans dead on Most of the damage due to levee failure following storm surge (more than 50 failures) --\> 80% city flooded Showed failures in US protection
101
Tornado watch
Tornadoes are possible in your area. Remain alert for approaching storms.
102
Tornado warning
A tornado has been sighted or indicated by weather radar. If a tornado warning is issued for your area and the sky becomes threatening, move to your pre-designated place of safety.
103
What is the Enhansed Fujita Scale used to measure tornadoes? How is the scale created?
Rate the strength of the tornadoes in the US and Canada based on the damage they cause. Implemented in place of the Fujita scale It was revised to reflect better examinations of tornado damage surveys, so as to align wind speeds more closely with associated storm damage. Better standardizing and elucidating what was previously subjective and ambiguous, it also adds more types of structures and vegetation, expands degrees of damage, and better accounts for variables such as differences in construction quality.
104
3 common myths about tornadoes
It is thought by some people that taking shelter under highway overpasses or in the southwest corner of the building provides extra protection from a tornado, but both of these probably increase the danger of injury or death. Some still believe that opening windows ahead of a tornado will reduce the damage from the storm, but this is not true. Some people also believe that escaping in a vehicle is the safest method of avoiding a tornado, but this could increase the danger in some situations.
105
What is the highest wind speed ever recorded in a tornado?
318 mph
106
What is the relationship between thunderstorms and tornadoes?
Thunderstorms produce tornadoes
107
How long do tornadoes last?
Several seconds to more than an hour.