Test 3 Water and Soil

You are buying a home in Ralston, located in Zone B with no previous flooding. The home costs $250,000 and has no basement. How much should you expect your flood insurance rate to be?

$552.50/year

At approximately what velocity will a 0.1 mm sediment particle begin moving in the stream?

0.6 cm/sec

A stream is transporting Particle A. The velocity of stream is decreasing, but for the moment, Particle A is still moving. However, when the water drops below 50 cm/sec, Particle A falls below its fall velocity and is deposited. Based on this information, what is the likely particle size for this object?

10 mm

This image shows the gradient of the water table between Well A and Well B. Please note that the label for each well also displays the elevation of the water table in that well. Using the information present in the figure, calculate the hydraulic gradient of this cross section.

11.7 m/km

According to the map, how many total buildings in Hazard City are at a high risk for flooding during a 100-year storm event? Note that buildings are marked as black and red squares on the map.

3

What is the minimum velocity needed for a 0.8 mm sand particle transition from a state of deposition to transportation?

5 cm/sec

What is permeability?

Ability to transmit water

Which of the following accounts for the largest usage of groundwater in the United States?

Agriculture and irrigation

What is the difference between an aquifer and an aquitard?

An aquifer is a rather permeable rock, whereas an aquitard is an impermeable rock

Briefly describe a general drainage basin.

An area drained by a stream is called a drainage basin, which is bounded by an imaginary line called a divide. The divide can be clearly visible as a sharp ridge, or it could be difficult to determine in subdued topography.

How does an oxbow lake form?

An oxbow lake forms when the bend of a meandering river is isolated from the river because erosional forces create a cutoff in the main river channel. This isolated bend becomes the oxbow lake.

X marks the site of oil drums that were illegally buried by the Shay-Dee Oil Corporation. These oil drums have begun leaking and the leaking oil has flowed downslope to the stream below, contaminating the stream. Which stream drainage basins would be affected by this oil?

C and A

Which acid, found in most groundwater, is responsible for most karst topography worldwide?

Carbonic

Which of the following materials would make the best aquitard?

Clay

A new housing development is being built upstream. How might this affect flooding in Hazard City?

Development can cause more water runoff into a stream and increase the potential for flooding.

Which weathering process is illustrated in this image?

Frost wedging

In order for an aquifer to be useful for reliable water extraction, what kind of porosity and permeability should it have?

High porosity, high permeability

________ is decayed remains of plant and animal life.

Humus

If the Palouse River is dammed upstream, how might this affect future flooding in Ralston?

It could lower Clearwater River, decreasing the amount of water in its tributary, and decrease the risk in Ralston.

How do natural levees form?

Levees form as the result of the repeated flooding of a river within a floodplain. Each time the floodwaters recede, the suspended load that had been carried by the water is deposited, building up levees along the banks of the river.

Which location marks the cutbank on this image?

Location A

How do the products of the two categories of weathering differ from each other?

Mechanical weathering results in broken pieces that are of the same composition as the original material, whereas chemical weathering alters the composition of the material.

Which of the following components makes up the largest percentage of most soils?

Mineral portion

________ are the primary source of organic matter in soils.

Plants

Please contrast porosity and permeability.

Porosity is the percentage of the total volume of rock or sediment that consists of pore spaces, whereas permeability is the ability of a rock or sediment to transmit fluid.

Which environmental issue most commonly affects groundwater aquifers in coastal or island areas?

Saltwater contamination

What is the ultimate base level?

Sea level

What do the zone designations for each site mean for flood probability?

Site 1 has a greater probability for flooding than Site 3. Site 2 has a greater probability for flooding than Site 1.

A flood greater than the 500-year flood travels through Hazard City. Which side of the river would be safest to live on?

South

The points on this figure mark the locations of groundwater observation wells. The numbers refer to the elevation of the water table above sea level. Using this information, determine the direction of groundwater flow in this region. Assume that the top of the figure is north.

Southwest

What does each zone designation mean for each neighborhood?

The Hazard City railroad on the south side of the river lies in Zone B and is only in danger of floods larger than the 100-year flood event. All of Downtown is within Zone C and is relatively safe from flooding.

Highways are indicated by bold red lines on the map. How can Highway 857 potentially affect flooding in Hickory Estates?

The bridge across the river could block water flow, causing higher water levels and increasing the potential for flooding.

What is base level?

The downward limit of erosion.

Paleoflood (ancient flood) deposits have been found in parts of Ralston that are currently in Zone C. Which of these answers provides a possible explanation for this finding?

The flood map is drawn incorrectly. The river was previously located closer to Ralston and has moved. The river system experienced a flood greater than the 500-year flood.

Running water is the single most important erosional agent sculpting Earth's land surface.

True

How does regolith differ from soil?

Unlike regolith, which consists only of weathered rock and mineral fragments, soil also contains organic matter, water, and air.

What is porosity?

Volume of pore space in a material

Which community has the least risk of flooding?

Walnut Heights

How will the water table respond when there is a drought?

Water table will fall

The ________ is the point in the subsurface where 100% of the pore spaces are filled with water.

Zone of Saturation

Stream gradient is calculated as the change in elevation (measured in feet) divided by the distance traveled (in miles). Using the base flood elevation lines on the map, what is the stream gradient of the main trunk of Clearwater River shown on the map? Recall that 5280 feet = 1 mile.

approximately 3 feet/mile

A(n) ________ stream is a stream that is in equilibrium and is neither eroding or depositing material, but simply transporting it.

graded stream

What are the two basic categories of weathering?

mechanical and chemical

On the Hazard City map, the blue feature running through Riverside and Ralston is a river system. Which direction is the river system flowing through Hazard City?

toward east