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GEOG311 > coastal management > Flashcards

coastal management Flashcards

(46 cards)

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1
Q

coastal management is?

A

balance, resources, environments and hazards

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2
Q

main goals of coastal management?

A
  • monitor and manage interactions to minimise conflict and damage to envrs,
  • moderate human interactions with coastal envr
  • sustainably manage coastal resources and hazards
  • integrate different values, uses, sub envrs
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3
Q

in coastal management what must always be considered?

A

time and space scales that coasts, humans uses, management plans & solutions need to operate over.

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4
Q

space and time periods

A

instaneous, event , engineering, geological

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5
Q

coastal monitoring

A
  • current state assessed
  • natural variability understood
  • envr monitored to detect long term trend changes (physical/ecosystem behaviour)
  • regional observations of sea levels waves, sst, water quality, dissolved co2
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6
Q

coastal development in nz

A
  • accelerated after wars
  • kiwi batch culture
  • the retirement dream (rapid increase in coastal development)
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7
Q

NZ coastal policy statement

A

natural character as signifcant value

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8
Q

why do we need coastal management

A

because we have important infrastructure (industrial) and many communities/cities on the coasts ! including lifelines (state highway, ports, airports, road networks)

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9
Q

coastal hazard

A

unwanted interaction btw humans and natural systems. people issue.

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10
Q

NZ coastal management structure (rules to follow)

A
  1. RMA and Minstry for envr,
    - NZCPS, DOC
    - regional/district councils and envr plans
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11
Q

possible issues with coastal development

A

erosion

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12
Q

coastal development ideal characteristics?

A
  • behind active dunes (need minimal intervention for storms etc)
  • veg and sediment protected
  • natural character, ecosystem and amenity value protected
  • infrastructure is non-damaging to coast (including disaster recovery
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13
Q

when do natural coastal processes become hazards?

A

when people, properties, infrastructure are adversely affected.

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14
Q

why is it important to include coastal communities in discussions about coastal management

A

ensures decision making is incorporating local knowledge leading to more effective and sustainable solutions.

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15
Q

what is dapp

A

dynamic adaptive pathway planning.
- develops series of actions over time (pathways) - make decisions as conditions change.

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16
Q

hazard management options

A
  • do nothing
  • avoid
  • accomodate
  • retreat
  • protect
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17
Q

what three factors make up a coastline

A

waves, sediment, storm

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18
Q

what two factors impact coastline

A

vegetation and humans

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19
Q

1-4 hazard management options all include what?

Study These Flashcards
A
  • land loss & coastal flooding allowed
  • some coastal function/value lost but,
  • allows for some natural processes and natural adjustment in response to changing sea levels
20
Q

to calculate coastal hazard management what do we need to know / do

Study These Flashcards
A

long term records and monitoring
good storm/storm cut records
prediction for 100yrs or more
assess climate change (is the past an indicator for future?)
safety aspect.

21
Q

protection coastal hazard management option

Study These Flashcards
A

holds the line (temporarily)
common in NZ (less common globally)
coastal land protected but coastal functions and values lost
expensive long term

22
Q

hard shore-based structures

Study These Flashcards
A
  • revetments
  • embankments
  • seawalls
    protect the edge of land against erosion (they are fixed in the line of the coast). dissipate wave energy
    need a lot of planning
23
Q

what are hard structures made out of and how shaped

Study These Flashcards
A

concrete, steel, timber
can be vertical or steepened or curved (depending on wave energy, more energy =more curve)

24
Q

revetments

Study These Flashcards
A
  • durable material (stone mineralogy = important, can’t have it eroding and changing processes of beach)
  • stone or unit shaped to lock in place
  • modest size and cost compared to sea wall
  • short life span (not suitable for high energy coasts)
    dynamic = gravel/rubble beach
25
embankments (and soft seawalls)
- used in flooding zones (estuaries) and low energy coasts. - sloped and concrete (engineered), dissipation of energy not needed just for flooding. soft seawalls - bags filled with sand/debrief stacked up (need to be careful with what your filling it with - not hazard to beach if break) - porous so will filter water through
26
seawalls
- designed to resist storm surge and protect from wave overtopping - dissipate wave energy (with curved top) - protect high value infrastructure behind - stops sediment transport - reduce impact of waves and currents - prevent saltwater intrusion - may reduce storm damage - need a LOT of planning - if get wrong or climate changes - too costly to fix
27
annual exceedance probability (AEP)
probability that an event of a given magnitude or larger will occur in any given year. expressed in %
28
average recurrence interval (ARI)
average time interval between events of specific mag or bigger. averaged over long time periods expressed in years.
29
how will ARI change with CC
as CC increases the frequency of storms the return period will decrease
30
seawall issues
- maintenance costs (fail without) -- (scouring = need for riprap additions) - limited life time - encourages development-disaster cycles and unhealthy attitudes towards the coast - interfere with alongshore drift
31
riprap
curved or stepped seawall additions to absorb/dissipate some wave energy reducing reflection. (needed due to scouring)
32
scour
erosion at the seabed at the base of the seawall by wave action, also occurs at the end of the seawall (END Effects) - could extend seawall
33
how do seawalls hold the land?
temporaliry
34
what are sea walls protecting
property not the coast - many aggravate beach loss due to increased wave reflection and scour! INCREASED EROSION.
35
seawalls and drainage?
need some sort of drainage system for rainfall and if water did overtop the sea wall. IF NOT - cause flood issues. water can cause undermining and failure.
36
coastal ecosystem squeeze?
The compression of coastal ecocsystems when a seawall is put in and now they are trapped btw barrier and rising SL. preventing their natural migration.
37
seawalls and land tectonics
if land moves (subsides) the sea wall may no longer be effective.
38
gryones and shore attached breakwaters
- perpendicular to the coast - protect land and maintain beach by trapping sediment (longshore drift) - shelter from waves - means somewhere else is missing out.
39
groyne issues
- sediment starvation & enhanced erosion down drift: trap efficiency often ~100% - rip cells often develop, moving sand into deep water, resulting in recreational hazard & extra loss of sand from the littoral cell.
40
breakwaters and artificial reefs
- Breakwater: wave sheltering more important than trapping sediment (in some cases) - Artificial reefs: create surf break OR stem erosion problem not both - detached from shore (parallel) - allows some longshore sediment transport - very expensive : exposed to energetic wave action - offshore structures cost 3-5x shoreline structures
41
soft options
beach nourishment dune enhancement
42
beach nourishment
- treats coastal erosion symptom (beach loss) not the cause (sediment deficit, sea level rise) - expensive and has to be maintained - lack of understanding - few adverse effects on surrounding beaches alone - often used with hard structures - taken from somewhere else which puts that location into a deficit - longer the stretch of beach = longer the nourishment effects last
43
for beach nourishment what size should the new sediment be?
same size or coarser than natural sediment
44
where do you source the sediment sources ?
old dunes estuaries dredge spoil (under RMA, need 2 consents)
45
what places are well suited to beach nourishment
places of high amenity/ recreation value beaches
46
dune enhancement
- use fences /vegetation to trap sand - adequate width/room for dune formation (buffer zone) - often used in combination with beach nourishment

GEOG311 (7 decks)

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