Floods and Floodplain Management

Question 1

What are the three most common types of flooding?

Answer 1

Riverine, coastal, shallow

Question 2

Which type of flooding has accounted for the most flood-related deaths in recent history?

Answer 2

Flash flooding.

Question 3

What is a “meander?”

Answer 3

It’s a curve or turn in a river channel.

Question 4

What’s the major cause of coastal flooding?

Answer 4

Storm surge.

Question 5

What causes a tsunami?

Answer 5

Underwater earthquakes or volcanoes.

Question 6

List the five types of special flood hazards covered in this course. Does your community have any of these?

Answer 6

— Closed basin lakes
— Uncertain flow paths
— Dam breaks
— Ice jams
— Mudflows

Question 7

List at least three benefits that floodplains, in a relatively undisturbed condition, actually contribute or could contribute to your community.

Answer 7

Although this depends on the community,
there are a large number of benefits they could potentially provide.

Question 8

What two problems result from floodplain development?

Answer 8

• Development alters the floodplain and the dynamics of flooding.
• Buildings and infrastructure are damaged by periodic flooding.

Question 9

What does watershed development do to flooding?

Answer 9

The increase in impervious surface results in increased runoff and higher flood levels.

Question 10

What is one of the problems with constructing seawalls to protect buildings from flooding or erosion?

Answer 10

It can accelerate erosion on properties at the end of the wall.

Question 11

What are the five main causes of flood damage?

Answer 11

Hydrodynamic forces
Debris impact
Hydrostatic forces
Soaking
Sediment and contaminants

Question 12

Standing water as little as ______ feet deep can collapse the walls of a frame house.

Answer 12

Three feet

Question 13

What are some of the safety and health hazards that accompany floods?

Answer 13

Disruption of public utilities
Electrocution
Contamination of water supplies
Fire
Animal carcasses, garbage and ponds that can become breeding grounds for germs and mosquitoes.
Mold, mildew and bacteria that grow in damp, flooded areas
Contaminated air from dirty heating ducts
Stress and mental health problems.

Question 14

Prior to the 1960’s what was the primary way to reduce flood losses?

Answer 14

Structural flood control projects

Question 15

What is the Unified National Program for Floodplain Management’s definition of “floodplain management?”

Answer 15

“A decision-making process that aims to achieve the wise use of the nation’s floodplains.”

Question 16

What are the two primary goals of floodplain management?

Answer 16

To reduce the loss of life, disruption, and damage caused by floods;
To preserve and restore the natural resources and functions of floodplains

Question 17

What areas are conducive to flash flooding?

Answer 17

-Hilly areas with steep slopes and narrow valleys
-Urban areas with large amounts of impervious surfaces and storm sewers -Areas downstream of dams or subject to ice jams

Question 18

Is erosion only a threat in coastal areas?

Answer 18

No. Riverine erosion can move stream channels and undercut structures.

Question 19

What is “ponding?”

Answer 19

Where stormwater runoff collects in depressions and cannot drain out.

Question 20

Are plants and animals the only beneficiaries of the “natural and beneficial functions” of floodplains?

Answer 20

No. People benefit from floodplains through the food they provide, the recreational opportunities they afford and the scientific knowledge gained in studying them. Floodplains also recharge groundwater supplies and their filtering actions help improve water quality.

Question 21

What does filling in a floodplain do?

Answer 21

Filling reduces the floodplain’s ability to store excess water, sending more water downstream and causing floods to rise to higher levels.

Question 22

Does moving sand and sand dunes affect flooding?

Answer 22

Yes, it may remove a natural barrier that protects inland properties.

Question 23

Hydrodynamic forces are caused by ______________ water and hydrostatic forces are caused by ______________ water.

Answer 23

Moving, standing

Question 24

List three materials or household items that are particularly susceptible to flood damage by soaking.

Answer 24

• Wood
• Gypsum wallboard
• Furniture and upholstery - Carpeting
• Mattresses
• Books
• Electrical appliances
• Gasoline engines

Question 25

What are examples of non-structural flood protection measures?

Answer 25

• Regulations to prohibit development in high-hazard areas.
• Building codes requiring flood-resistant construction for new buildings in floodprone areas.
• Acquisition and relocation of buildings in high hazard areas. - Modifying or retrofitting existing buildings.
• Installing flood warning systems.
• Controlling stormwater runoff.
• Providing self-help advice to property owners.

Question 26

What are the Unified National Program for Floodplain Management’s four main floodplain management strategies?

Answer 26

• Modify human susceptibility to flood damage
• Modify the impact of flooding
• Modify flooding itself
• Preserve and restore natural resources