Geosci Unit 4 Review

A stream channel is widened by erosion, but stream discharge is unchanged. Which of the following statements must be true? depth increased and/or velocity increased depth decreased and/or velocity increased depth increased and/or velocity decreased depth decreased and/or velocity decreased

-D -Discharge is velocity x cross section. -So, if the discharge stays the same in a wider stream, then either 1) depth decreased so that cross section stayed the same; or 2) cross section got larger so velocity had to decrease

What is the probability that a 10 year flood will happen in any given year?

10%

A rapidly growing city within a humid climate zone experiences a land use change from predominantly crop land to mostly urban/suburban. A likely natural response would be: Increased groundwater infiltration—reduced flooding Reduced groundwater infiltration—increased flooding Increased groundwater infiltration—increased flooding Reduced groundwater infiltration—reduced flooding

B

What do you think uses the most water in the US today? Human consumption (what we all use at home, work, etc.) Energy industry All agriculture All other industry

B

A majority of Earth's water is in the oceans. Predict what would happen to sea level if rain fell continuously all over the world's oceans. Sea level would rise Sea level would fall Sea level would stay the same

C

Approximately much more water is in groundwater than is in rivers and lakes? 2 times as much 10 times as much 100 times as much 1000 times as much

C

What is the discharge of a stream in a rectangular channel that has a cross-sectional area (width x depth) of 60 square meters, that is 40 kilometers long, and has a velocity of flow of 5 meters per second? 105 cubic meters per second 200 cubic meters per second 300 cubic meters per second 2400 cubic meters per second

C

What does it mean for a flood to be a "hundred year flood"? It's a really destructive flood. It only happens once every 100 years. There is a 1% chance that a flood of that size will occur this year. There is a 100% chance that a flood of that size will occur this year. If it's been 50 years since the last one, it'll be another 50 years before the next one. If it's been 50 years since the last one, it'll be another 50 years before the next one.

C There is a 1% chance that a flood of that size will occur in any given year.

California is in a severe drought in 2015. What is your prediction for the number of landslides under these conditions?

California is in a severe drought in 2015. What is your prediction for the number of landslides under these conditions?

If one person drills a 20 m deep well and finds a reliable water supply, what can his neighbor conclude? He needs to drill a 20 meter well also. He needs to drill a 25 meter well so he can get the water before his neighbor does. He needs to drill a 15 meter well so he can get the water before his neighbor does. He might also find water at 20 meters, but he might not because the gradient of a water table can change.

D

If rain falls on a gentle slope, which scenario will increase recharge of an unconfined (open) aquifer? light rain on clay heavy rain on clay light rain on sand heavy rain on sand

D

There was a 500 year flood on the Blanco River in Texas in May 2015. When will the next one be? 2515 No sooner than 2415 Not for at least 100 years No way to tell. Could be tomorrow, could be 3015.

D

What is a benefit of flooding events to natural ecosystems?

Delivery of nutrients to the stream banks, Washing away invasive species, Delivery of sediments to the stream banks

What are river gages mainly used to measure?

Discharges

Coastlines are best described as

Dynamic systems in constant change

If this sketch represents the water cycle, what is the name of the process for arrow #2? (land to atmosphere)

Evaporation

All else equal, a larger hydraulic gradient will cause groundwater to flow __________.

Faster

If this sketch represents the water cycle, where is most of the fresh water stored?

Groundwater

In a stream bed, how do larger pebbles and rocks get deposited above the average water level?

High discharge flooding

What happens during a glacial retreat?

Ice melts faster than it is replaced.

Which statement about river levees and floodwalls is FALSE?

Levees decrease the water volume flowing through channels during floods.

The Edwards Aquifer is developed in what type of rock?

Limestone

Which is NOT a fundamental reason why the central Texas Hill Country is the most flash-flood prone area of North America?

Located close to Gulf of Mexico, a large source of water

In which of these locations do you think the landslide risk is greatest?

Oregon Coast

Which of the following would make the best aquifer or oil/gas reservoir?

Sandstone with many connected pores

Which of the following can influence the size of floods?

Soil moisture, Snow depth and speed of melting, Amount of precipitation, Seasonal vegetation changes

Rivers are_____

Straighter in the hills and curvier in the flat lands

Hydraulic gradient of an unconfined aquifer is ________.

The slope of the groundwater table

A stream channel is narrowed by bridge construction. How will the velocity of flow change if the depth and discharge of the stream remain constant?

The velocity will increase

True or False: Water can be purified (at least to some extent) by the ground, because porous rock can act as a filter for both particulate and chemical contaminants.

True

In general, which would have the highest permeability?

Well-sorted gravel

Which of these factors do you think are important in the formation of barrier islands? Sediment supply is constant Sea level is falling Sea level is not changing Land is being uplifted Waves are medium to large sized Annual storms to bring new sand

a and c

Aquifer

a rock with pore space saturated with water

Aquiclude

a shale layer

A glacier is

a slowly moving mass of ice and snow

In addition to the three we discussed, which of these do you think changes or shapes coastlines? (Choose all that apply) Tides Tectonic processes Biologic processes Sea level changes Human influences

a,b,c,d,e

Conglomerates can form

at point bars in rivers

Given your experience, how would you classify the Texas Gulf Coast? (choose all that apply) Erosional Coasts Deposition Coasts Passive Margin Coasts Convergent Coasts Submergent Coasts Emergent Coasts

b,c,e

Which of the following geologic structures would you expect to see along the gulf coast?

barrier islands, offshore sand bars, sand dunes

Cone of depression

develops around water wells with pumping

An artesian well can occur in an unconfined aquifer. T or F?

false

True or false: a stream located in a rural area will flood more quickly than an urban stream due to increased infiltration. T or F?

false

By definition, below the water table pores in a sandstone would be ____.

filled with water

Sand dunes get their sand

from the beach, by wind

All of the things listed are places water can be found. Which list is the in right order, from most to least amount of Earth's water? (Yes, ocean is the biggest - we left that off.)

ice, groundwater, rivers and lakes, soil, atmosphere

Spring

intersection of the water table and and land surface

A confined aquifer

is an aquifer that is separated from the surface by a layer of rocks of low permeability

Barrier islands are typically found

on continental margins that are not also plate boundaries

Artesian well

only occurs in confined aquifers

Which of the following can cause landslides?

rain, wave erosion, vegetation loss, earthquake

River terraces form by_____

repeated flooding over several years and repeated flooding over several years

If a glacier is in equilibrium (accumulation = ablation), what occurs at the terminus?

sediment is deposited

In general, what kind of rock is most likely to have both high porosity and high permeability?

sedimentary

Creep

soil moves slowly downslope (1cm/yr), no discrete failure planes, vegetation adjusts to the slope

When an UNCONFINED well is pumped dry, the level of nearby CONFINED wells will_______and nearby UNCONFINED wells will_______

stay the same, drop

The height of the water in a well in an unconfined aquifer indicates-

the height of the water table

Ablation refers to

the loss of mass from a glacier by melting and sublimation

why do glaciers leave behind u shaped valleys

they erode and scour the landscape as they move downhill

TRUE/FALSE A rock can be porous but not permeable. True False

true

A series of elevated terraces (former wave-cut platforms) along an active plate boundary coast is evidence for ______________.

uplift of the continental crust