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Geohazard > Flooding - Human Activity and Flooding > Flashcards

Flooding - Human Activity and Flooding Flashcards

1
Q

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

A

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

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2
Q

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

A

t

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3
Q

land-use factors that affect flooding

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

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

A
  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
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5
Q

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

A

sediment pollution

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6
Q

how does sediment pollution affect flooding?

A

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

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7
Q

this refers to the level of suspended sediments

A

turbidity

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8
Q

why are wetlands important in reducing flooding?

A

wetlands are natural flood-retention basin, they accumulate floodwater

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9
Q

land consisting of marshes or swamps; saturated land

A

wetlands

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10
Q

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

A

topographic depressions ; adjacent to river channels ; riparian wetlands

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11
Q

how does destruction of wetland affect flooding?

A

reducing the landscape’s ability to store water

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12
Q

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

A

riparian zones

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13
Q

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

A

wastelands

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14
Q

t or f: wetlands are generally porous

A

t

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15
Q

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

A

culvert

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16
Q

what is the downside of using a culvert?

A

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

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17
Q

most construction activities involves _______thereby, increasing chances of flooding

A

removal of natural vegetation

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18
Q

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

A

desiltation

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19
Q

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

A

impermeable surfaces

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20
Q

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

A

t

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21
Q

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

A

t

22
Q

what are the consequence of urbanization?

A
  1. more frequent flooding
  2. higher flood crests
  3. shorter lag time between rainfall and peak discharge
23
Q

what are the flood mitigation measures?

A
  1. dams
  2. artificial leeves
  3. channelization
  4. retention basins
  5. erosion control
  6. flood proofing
  7. floodplain management/zoning
  8. education
24
Q

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

A

dams

25
Q

what is the downside of a dam?

A

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

26
Q

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

A

t

27
Q

built by humans to keep a river from overflowing its banks

A

artificial leeves

28
Q

large concrete panels used to build artificial leeves

A

floodwalls

29
Q

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

A

earthen leeve

30
Q

what is a the downside of artificial leeves?

A

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

31
Q

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

A

t

32
Q

involves straightening and deepening of a stream channel

A

channelization

33
Q

channelization increases a streams _________

A

discharge capacity

34
Q

channelization results in an increase in ________ and _______

A

stream gradient and water velocity

35
Q

what is the most serious consequences of channelization?

A
  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
36
Q

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

A

retention basins

37
Q

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

A

erosion controls

38
Q

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

A

stream buffers

39
Q

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

A

silt fences

40
Q

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

A

silt basins

41
Q

types of erosion controls

A

stream buffers, silt fences, silt basins

42
Q

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

A

geotextiles

43
Q

Involves raising the building above the expected flood level

A

flood proofing

44
Q

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

A

sandbags

45
Q

involves providing federally subsidized flood insurance to property owners

A

Flood Plain Management

46
Q

how is a flood map for flood plain management generated?

A

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

47
Q

flood plain management is sometimes called

A

floodplain zoning

48
Q

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

A

floodplain zoning

49
Q

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

A

flood fringe ; floodway

50
Q

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

A

public education

51
Q

Approximately half of all flash flood fatalities are ______

A

vehicle-related

52
Q

flood susceptibility is divided into how many classes?

A

4 classes

very high
high
moderate
low

Geohazard (25 decks)

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