Dams

Question 1

Why are the largest dams in the Western United States?

Answer 1

• Need more water storage in arid region
• Mostly built in 20th century with modern technology and equipment
• Need deep valleys to build large dams
• Lost of land owned by federal government

Question 2

What was the first dam built in the United States?

Answer 2

Croton Dam, New York State

Question 3

To make electricity you just need?

Answer 3

Rotational energy or generators

Question 4

What is the most common way to harness the power of water?

Answer 4

hydroelectric dam

Question 5

What types of dams produce most power?

Answer 5

Tall dams (big drop) with large river (big reservoirs of water)

Question 6

Steps of hydroelectric dam

Answer 6

1. Water flows in through penstocks
2. Flowing water propels turbine into motion
3. Turbine rotates within generator to produce power
4. Water flows through penstick back out into river

example of non-consumptive water use

Question 7

Hydroelectric power involves the conversion of the potential energy of water stored behind a dam to kinetic energy to generate electricity. What is the ultimate source of the potential energy?

Answer 7

Solar energy (sun)

Question 8

The amount of electric power a hydroelectic dam can generate is the product of what two factors?

Answer 8

dam elevation and water discharge (need tall dam with large river)

Question 9

Why did flood control fams in the Houston area exacerbate flooding during Hurricane Harvey in 2017?

Answer 9

• the dams were in danger of failing, so water had to be released rapidly
• it is very hard to manage > 30 inches of rainfall in a few days in an urban area
• homes had been built in the area flooded by the dams

Question 10

Where does the water we use at BC come from?

Answer 10

Swift River in central MA

Question 11

How many years did it actually take to fill the Quabbin Reservoir after the Winsor Dam was built in 1939?

Answer 11

7

Question 12

According to the article by Kelly (2017, New York Times), what is the US Army Corps of Engineers’ proposed solution to the problem of climate change increasing flood risk on the Missouri River?

Answer 12

move levees farther away from the river

Question 13

What does the exchange of discharge look like in a run-of-the-river dams?

Answer 13

Qin = Qout

Question 14

What does the exchange of discharge look like in a flood detention dam with light precipitation?

Answer 14

Qin > Qout

Question 15

What does the exchange of discharge look like for a flood detention dam when a large storm hits an area?

Answer 15

Qin <Qout

Question 16

What does the exchange of discharge look like in a multipurpose storage dam?

Answer 16

Qin does not equal Qout

Question 17

What is the equation for solving how much water is conserved in a reservoir?

Answer 17

Input of water = Output + change in storage

OR

Input of water - discharge into the reservoir

Output of water - discharge out of the reservoir

Question 18

What is the change of storage?

Answer 18

change in the volume of water in a reservoir per time

Question 19

What are the pros of dam construction?

Answer 19

• Flood control
• Water storage
• Harnesses water supply for public and agricultural use
• Recreational activities (fishing, swimming, boating)
• Cheap energy source
• Energy generation
• Clean source of water

Question 20

What are the cons of dam construction?

Answer 20

• Destroys habitats (disrupts fish migration and leads to chemical runoff)
• Displaces humans
• Flood control is limited (less effective downstream)
• Less recreational activities downstream
• Can often fail (broken dam in China killed thousands of people)
• Channel and floodplain can disconnect