Exam 3

Question 1

What does the rock cycle explain ?

Answer 1

Explains interrelations among earth materials

Question 2

What are the three main types of rocks ?

Answer 2

Igneous: can be changed into sed. rock or into meta. rock
Sedimentary: can be changed into meta. rock or onto igneous rock
Metamorphic: can change into igneous or sed. rock

Question 3

What are the six pathways ?

Answer 3

Heat and pressure 
Crystallization 
Melting  
Uplifting 
Weathering, erosion, and deposition
Compaction and cementation

Question 4

What is metamorphism ?

Answer 4

The process that changes sedimentary and igneous rocks into metamorphic rock
Alteration of the minerals and textures of a rock by changes in temperature and pressure, and/or by a gain or loss of chemical components

Question 5

What is erosion ?

Answer 5

The processes that loosen sediment and move it from one place to another on earth’s surface

Question 6

What is weathering ?

Answer 6

The breaking down of rocks, soil and mineral as well as artificial materials through contact with Earth’s atmosphere, biota and waters

Question 7

What are the two types of weathering ?

Answer 7

Physical weathering- no chemical changes
Chemical weathering- the process by which rocks are decomposed, dissolved, or loosened by chemical processes to form residual materials, chemical changes

Question 8

How is sediment transported ?

Answer 8

The processes that carry sediment or other materials away from their point of origin

Question 9

What is sediment deposition ?

Answer 9

The settling of materials out of a transporting medium like water or wind

Question 10

Describe lithification and two related phenomena

Answer 10

The process by which sediment is converted into sedimentary rock including cementation and compaction

Question 11

Define the term stream

Answer 11

A body of water flowing in a channel or watercourse

Question 12

What is a flood ?

Answer 12

A rising and overflowing of a body of water especially onto normally dry land
A large amount of water covering an area of land that is usually dry

Question 13

What are the most important factors that control the way a stream behaves ?

Answer 13

Gradient 
The cross sectional area of the channel
The average velocity of the water
Discharge 
Load

Question 14

What is stream gradient ?

Answer 14

Water on a slope (which all channels have) will be influenced by gravity
That’s the energy in the system.
Gravity pulls the water downstream
The vertical distance that a channel falls between two points along its course is the gradient
Elevation changes of the vertical distance

Question 15

What is stream velocity ?

Answer 15

The speed at which water flows through a stream

Question 16

Describe discharge

Answer 16

The quantity (volume) of water passing by a given point in a certain amount of time

Question 17

What is hydraulic action ?

Answer 17

The erosion that occurs when the motion of water against a rock surface produces mechanical weathering

Question 18

How are larger particles (bed load) transported in a stream ?

Answer 18

Moves by rolling, sliding, and/or saltating (hopping). Generally, bed load downstream will be smaller and more rounded than bed load upstream

Question 19

What is the term for transported particles that stay close to the bed, but aren’t in contact with it; they bounce or jump ?

Answer 19

Saltation

Question 20

How is most of a stream’s load transported and what material is it made of ?

Answer 20

Stream load is composed of dissolved or solution load, suspended load, and bed load
The dissolved load comes primarily from groundwater seepage into the stream
Ions in solution also come from the solution of materials that line the channel

Question 21

What happens to sediment when the stream velocity decreases ?

Answer 21

A river will deposit a part of its load of sediment when either its velocity or its discharge decreases

Question 22

What marks the edges of floodplain ?

Answer 22

Levees

Question 23

What three conditions change stream discharge ?

Answer 23

Transition from a drought to a wet period
Times of heavier rainfall or snow melt
Where tributaries add water to the stream

Question 24

What factors influence stream velocity ?

Answer 24

By the slope of the surrounding terrain, the depth of the stream, the width of the stream, and the roughness of the substrate or stream bottom
If the surrounding terrain is steep, then rain water and snow melt will have less time to soak into the ground and runoff will be greater

Question 25

What is channel roughness ?

Answer 25

A measure of the resistivity offered by the material constituting stream channel margins to the flow of waterx

Question 26

Describe a meandering channel

Answer 26

Series of smooth bends

Question 27

Where is sediment deposited ? Eroded ?

Answer 27

Can be found anywhere in a water system, from high mountain streams, to rivers, lakes, deltas and floodplains

Question 28

Describe a braided channel (include comments on water velocity)

Answer 28

Resembles pattern of braided hair - water repeatedly divides and reunites

Question 29

Describe a floodplain

Answer 29

The flat area along a stream channel

Question 30

What is a river system ? How does it change along the length of the river course ?

Answer 30

Drainage system

Question 31

What is the importance of streams or rivers ?

Answer 31

Drinking water Domestic uses Source of food Agriculture –Fertile soils, irrigate land Transportation and communication •Riparian (land/water interface zone) habitat A riparian zone or riparian area is the interface between land and a river or stream. Significant in ecology, role in soil conservation, habitat biodiversity, and the influence they have on fauna and aquatic ecosystems Natural biofilters - protect aquatic environments from excessive sedimentation, polluted surface runoff and erosion

Question 32

What needs to be known to plan for floods ?

Answer 32

Where the floodplain and flood-prone areas are. How often the floodplain will be covered by water. How long the floodplain will be covered by water. At what time of year flooding can be expected

Question 33

What type of data/information are needed to calculate flood frequency and probability ?

Answer 33

Recurrence intervals

Question 34

What is the flood recurrence interval ?

Answer 34

when there is a magnitude associated with the data (such as discharge with a flood or seismic moment with an earthquake) the recurrence interval (T) is T = (n+1)/m where n is the number of years of the record and m is the magnitude ranking

Question 35

How does urbanization impacts flooding ?

Answer 35

Change in infiltration

Question 36

What factors contribute pollutants and dangerous contents in flood water ?

Answer 36

Human and livestock waste. Household, medical, and industrial hazardous waste (chemical, biological, and radiological) Coal ash waste that can contain carcinogenic compounds such as arsenic, chromium, and mercury. Other contaminants that can lead to illness

Question 37

Explain each of the two styles of flood

Answer 37

Flash floods: Cause - large thunderstorms that build up and release water quickly Steep topography aids in building thunderstorms and provides steep valleys to channel water Most flood-related deaths in U.S. are caused by flash floods Have flash floods in Las Vegas Water one - two feet deep can buoy up (lift) a vehicle Regional flood: High water may cover an area for weeks Typically few deaths, but great damage (Evacuation can be done.) Occur in large river valleys with low topography Usually associated with spring snowmelt or summer rain

Question 38

What are some types of damage caused by floods ?

Answer 38

Primary Secondary Tertiary

Question 39

How does the sediment load relate to flood damage ?

Answer 39

Large sediment accumulations can cause upstream flooding, or deflect the flow into the adjacent stream bank or even onto adjacent land, causing further erosion. In addition sediment can fill the deep permanent pools of rivers to ruin this critical refuge habitat

Question 40

What are the categories of flood severity ?

Answer 40

Minor flood Moderate flood Major flood

Question 41

What are primary effects of floods ?

Answer 41

Mortality Flood specific mortality rates vary by country. In flood prone Bangladesh, ~15,000 people are killed each year by floods In the U.S., >20,000 cities and communities are subject to flash flooding Avg. annual loss of life is 47.6 - 146 deaths; avg. 37 deaths per major flash flood U.S. Flood fatalities from 1940-2013 is a total of 3309 people, with a 10-year average of 75 per year and a 30-year average of 85 per year. These are the largest values of any of the weather-related disasters. China – 40 - 60 million inhabitants are affected yearly by flooding - 1000 people died in 1994 Drowning in the most common cause of death in flash flood incidents. Drowning, stress and overexertion from fleeing and cleaning up all contribute to the death toll. About half of the people who die in flash floods make one fatal mistake - driving into flood water Caused by actual impact with flowing water

Question 42

What are secondary and tertiary effects ?

Answer 42

Are longer term impacts that are indirectly related to flooding

Question 43

What is flood hazard mapping and why is it done ?

Answer 43

An exercise to define those coastal areas which are at risk of flooding under extreme conditions. As such, its primary objective is to reduce the impact of coastal flooding. However, mapping of erosion risk areas may serve to achieve erosion risk reduction

Question 44

What are some engineering solutions to flooding and how do they work ?

Answer 44

Dams - Dams can be used to hold water back so that discharge downstream can be regulated at a desired rate. The water level can be lowered prior heavy rains, and trapping water in the reservoir and to release later at a controlled discharge. Detention ponds - Detention ponds traps water and then release at a controlled discharge, usually infiltration, to prevent flooding downstream. Levees, Dikes, and Floodwalls - They are built along side the channel to increase the height at which the stream floods. Some controversy has developed concerning the use of such structures. Floodways/spillways are areas that can be built to provide an outlet to a stream and allow it flood into an area that has been designated as a floodway. Floodways are areas where no construction is allowed, and where the land is used for agricultural or recreational purposes when there is no threat of a flood, but which provide an outlet for flood waters during periods of high discharge

Question 45

When is flash flood season in southern Nevada ?

Answer 45

July-September

Question 46

What do we prepare for flooding ?

Answer 46

An engineering approach to control flooding A regulatory approach designed to decrease vulnerability to flooding Preparedness by predicting and forecasting flood times and locations Education of the public

Question 47

What happened in the 1970s after the Casear’s Palace flood ?

Answer 47

Hundreds cars got flooded in

Question 48

What is the purpose of the local flood master plan ?

Answer 48

The plan can highlight local problems such as flood risk and develop policies for land use to allow communities to manage this risk