Flooding - Human Activity and Flooding

Question 1

what type of human activities has increased the frequency and severity of flooding?

Answer 1

clearing of land for agriculture, building of cities, and construction of transportation networks

Question 2

t or f: some measures to reduce flooding in one area have led to increased flooding in other areas

Answer 2

t

Question 3

land-use factors that affect flooding

Answer 3

1. removal of natural vegetation
2. destruction of wetlands
3. construction activity
4. urbanization

Question 4

what are the consequences of widespread removal of forests and grasslands?

Answer 4

1. less infiltration capacity resulting to more overland flow and increases the ability of water to move downslope
2. increased overland flow and erosion thereby resulting in sediment pollution

Question 5

excessive dislodged sediment is moved off the
landscape into drainage systems which causes
channels to become filled with sediment

Answer 5

sediment pollution

Question 6

how does sediment pollution affect flooding?

Answer 6

reducing the capacity of streams to carry water thereby increasing the frequency and severity of flooding

Question 7

this refers to the level of suspended sediments

Answer 7

turbidity

Question 8

why are wetlands important in reducing flooding?

Answer 8

wetlands are natural flood-retention basin, they accumulate floodwater

Question 9

land consisting of marshes or swamps; saturated land

Answer 9

wetlands

Question 10

wetlands are commonly found in ____________ and ____________ in which case they are called ___________

Answer 10

topographic depressions ; adjacent to river channels ; riparian wetlands

Question 11

how does destruction of wetland affect flooding?

Answer 11

reducing the landscape’s ability to store water

Question 12

are lands that occur along the edges of rivers, streams, lakes, and other water bodies

Answer 12

riparian zones

Question 13

in many parts of the world, wetlands have been viewed as __________

Answer 13

wastelands

Question 14

t or f: wetlands are generally porous

Answer 14

t

Question 15

large pipes called _____ are typically sued for small streams that flow intermittently

Answer 15

culvert

Question 16

what is the downside of using a culvert?

Answer 16

the amount of discharge able to flow through the culvert is limited to its diameter and is unable to handle large volume of water, thereby causing upstream areas to become flooded

Question 17

most construction activities involves _______thereby, increasing chances of flooding

Answer 17

removal of natural vegetation

Question 18

The process of removing silt from a body of water (e.g., sand and gravel extraction)

Answer 18

desiltation

Question 19

urban areas in developed countries typically have significant portions of the land covered with __________ such as concrete and asphalt, causing less infiltration capacity

Answer 19

impermeable surfaces

Question 20

t or f: urbanization leads to shorter lag times between precipitation events and peak discharge

Answer 20

t

Question 21

t or f: it takes far less time for overland flow to reach a stream channel than water infiltration and movement through the groundwater system

Answer 21

t

Question 22

what are the consequence of urbanization?

Answer 22

1. more frequent flooding
2. higher flood crests
3. shorter lag time between rainfall and peak discharge

Question 23

what are the flood mitigation measures?

Answer 23

1. dams
2. artificial leeves
3. channelization
4. retention basins
5. erosion control
6. flood proofing
7. floodplain management/zoning
8. education

Question 24

this serves as a protection against floods and as an important source of freshwater and electrical power

Answer 24

dams

Question 25

what is the downside of a dam?

Answer 25

heavy or prolonged rains can sometimes cause the reservoir to reach its maximum level, thereby engineers are forced to release water at such high rate causing flooding on the downstream areas

Question 26

t or f: structural failure of a dam can generate a truly catastrophic flood

Answer 26

t

Question 27

built by humans to keep a river from overflowing its banks

Answer 27

artificial leeves

Question 28

large concrete panels used to build artificial leeves

Answer 28

floodwalls

Question 29

any low ridge or earthen embankment built along the edges of a stream or river channel to prevent flooding of the adjacent land.

Answer 29

earthen leeve

Question 30

what is a the downside of artificial leeves?

Answer 30

they disrupt natural drainage system by disconnecting a river from its floodplain will hold far less water than what the floodplain is capable, thus, will act as bottlenecks restricting the flow of a river

Question 31

t or f: artificial leeves act as bottlenecks that make flood worse in upstream areas

Answer 31

t

Question 32

involves straightening and deepening of a stream channel

Answer 32

channelization

Question 33

channelization increases a streams _________

Answer 33

discharge capacity

Question 34

channelization results in an increase in ________ and _______

Answer 34

stream gradient and water velocity

Question 35

what is the most serious consequences of channelization?

Answer 35

1. flooding downstream becomes worse because in non channelized sections, discharge capacity remains the same 2. increased water velocity causes stream to erode downward, leaving steeper banks that are prone to mass wasting

Question 36

temporarily stores some the excess water in a series of depressions which are constructed within a tributary network

Answer 36

retention basins

Question 37

involves practices that tend to keep soil particles in place so as to minimize the amount of material able to move downslope

Answer 37

erosion controls

Question 38

are a type of barrier in which vegetated strips line the banks of stream channels, trapping sediment before it can enter the drainage network

Answer 38

stream buffers

Question 39

are made of a synthetic fabric that is fine enough to trap sediment, but yet allows some water to pass

Answer 39

silt fences

Question 40

ponds constructed for the purpose of trapping any sediment that makes its way into a drainage system

Answer 40

silt basins

Question 41

types of erosion controls

Answer 41

stream buffers, silt fences, silt basins

Question 42

fabrics used in geotechnical applications, such as road and railway embankments, earth dikes, and coastal protection structures, designed to perform one or more basic functions such as filtration, drainage, separation of soil layers, reinforcement, or stabilisation

Answer 42

geotextiles

Question 43

Involves raising the building above the expected flood level

Answer 43

flood proofing

Question 44

For those who do not plan ahead, there is always the possibility of constructing an emergency levee using

Answer 44

sandbags

Question 45

involves providing federally subsidized flood insurance to property owners

Answer 45

Flood Plain Management

Question 46

how is a flood map for flood plain management generated?

Answer 46

By comparing the elevation of the land surface to the projected flood height of a 100-yr flood

Question 47

flood plain management is sometimes called

Answer 47

floodplain zoning

Question 48

involves identifying areas adjacent to a stream that will be inundated in a 100 year flood.

Answer 48

floodplain zoning

Question 49

regulatory floodplain is divided into the ________ and ___________, and regulations then restrict the type of development allowed in each of these two zones.

Answer 49

flood fringe ; floodway

Question 50

a very cost effective means of reducing the number of fatalities and property damage.

Answer 50

public education

Question 51

Approximately half of all flash flood fatalities are ______

Answer 51

vehicle-related

Question 52

flood susceptibility is divided into how many classes?

Answer 52

4 classes very high high moderate low