River Management

Question 1

What are the goals of river management?

Answer 1

• flood control
• navigation
• recreation
• hydroelectric power generation
• water supply
• dams can accomplish all these functions *

Question 2

How do we manage rivers?

Answer 2

Dams
Levees
Channel modifications

Diversion (aqueducts & pipes)
Land use (manage runoff)
Locks

Question 3

What are run-of-the-river dams?

Answer 3

small dams; usually for power generation or water storage; most dams in NE U.S (no management of flow)

Question 4

What are flood-detention dams?

Answer 4

bigger dams; reservoir is usually kept empty, only filled during major storm events (reservoir low compared to dam)

Question 5

Multipurpose storage

Answer 5

big dams in the wester U.S.; water storage, plus power generation, flood control, and/or recreation

Question 6

What are the two strategies for flood control?

Answer 6

1. slow flow down (keep water in watershed)
   - Land use
   - Channel storage
   - Dams
2. Methods that speed flow up (move water through channels faster)
   - Levees
   - Channel straightening, deepening, other modifications

Question 7

The higher the peak discharge the worse ____________ there is

Answer 7

flooding

Question 8

What is land use planning?

Answer 8

IDing flood-prone areas & setting zoning requirements to ensure damages are limited to area

Question 9

What are some zoning requirements suggested by land use planning?

Answer 9

• avoid building residential areas in the floodplain
• protect building using pumps (if you do decide to construct)
• use floodplain land for parks, athletic fields, community gardens, forest buffers

Question 10

What is a bio filtration swale?

Answer 10

detention area where water can flow in and be taken up by groundwater and plants
- harvests rainwater

Question 11

Advantages of green roofs?

Answer 11

• Reduce stormwater runoff
• Reduce heating and cooling costs and energy usage
• Create habitats
• Improve air and water quality; reduce urban heat islands

Question 12

Disadvantages of green roofs?

Answer 12

• Cost more than traditional roofs
• Require ongoing maintenance (even irrigation)

Question 13

What happens when you take a meandering river and straighten it?

Answer 13

The river will wind up eroding its banks upstream and face deposition downstream
(if you straighten a river, must engineer the banks entirely)

Question 14

Channelization (straighter)

Answer 14

water will flow fast

Question 15

Channelization (smoother)

Answer 15

no concrete or vegetation

Question 16

Channelization (deeper)

Answer 16

floodwalls and levees ensure water does not overflow onto floodplain

Question 17

Channelization (trapezoidal)

Answer 17

minimize erosion

Question 18

Pros of channelization and levee projects for flood control

Answer 18

• move more water quickly through channels (faster, deeper flow) = protects cities
• work well to protect infrastructure during high-frequency, low-magnitude floods

Question 19

Cons of channelization and levee projects for flood control

Answer 19

• Levees fail catastrophically during big floods
• Flooplain cut off from channel, destroying habitats and losing temporary water storage on floodplains
• Increased erosion and deposition
• Faster transfer of flood peaks (spill over floodplain)

Question 20

What kind of flood control method would be appropriate for a small stream in a city (i.e. Muddy River)?

Answer 20

Land use planning in the floodplain

Question 21

What kind of flood control project would be appropriate for a large river flowing through a major city?

Answer 21

Channel straightening

Question 22

Which kinds of flood control projects work by moving water through channels faster?

Answer 22

Levees & Channel straightening & concrete channels

Question 23

Which of the following is a flood-control strategy that works by detaining water in the watershed?

Answer 23

using floodplains as parks

Question 24

Tallest Dam in U.S

Answer 24

Oroville Dam, CA