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BC > praias e dunas > Flashcards

praias e dunas Flashcards

1
Q

what is a beach

A

meeting of sea and land
has to have sediment accumulation

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2
Q

influences in beach shaping

A

wind, water movement, river runoff and human impacts

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3
Q

limit of area of a beach

A

furthest paces where there is sand movement (including underwater)

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4
Q

sediment movement influences

A

intro :
- dune erosion
- cliff erosion
- longshore transport
- biogenic sediment production
- artificial input
- rivers

loss:
- wind
- waves
- sand deposition
- longshore transport
- ripcurrents (influences offshore)

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5
Q

how wave influences sand mov

A

+ size = + transport of small particles = big sand in beaches

+ action =+ erosion = sandy beaches and low slope

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6
Q

beach types

A

de acordo com a acção das ondas:
exposed
protected

dissipative - summer
reflective - winter

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7
Q

praias com mais vasa/ areia significa
Há input ou removal

A

há + input do que remoção

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8
Q

caract praia dissipativa

A
  • ondas quebram numa vasta area
  • pouca prof
  • areia fina
    • estável
  • Baixa taxa de escorrência (+ bact)
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9
Q

caract exposed beach

A

+ wave action
+ sediment
due to geomorphology this doesn’t change unlike dissipative vs reflective

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10
Q

sand origin
By type of sand

A
  • Biogenic = calcareous – shells, corals, erosion of fossils
  • Geologic = silica or quartzo – volcanic, land origin
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11
Q

caract sand

A
  • diameter of grains
  • porosity
  • permeability
  • penetration related to % of clay – amount of water holed by the sediments (silt and clay – vasa e lama)
  • big particles – water flows through it – less stable - less fauna
  • MOP – particular organic material – food for organisms
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12
Q

what does sand grain influence

A

+ size = easily dried + less stable = less biodiversity

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13
Q

caract of big sediments

A

+water in between sediments

but - retention

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14
Q

smallest sediment sizes name

A

vasa e lama

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15
Q

cract of vasa

A

compact more closely
= - porosity

but can + porosity too
because clay has + SA

  • permeability
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16
Q

the greater the porosity,

A

the greater the permeability

17
Q

why is permeability and ability to retain important in sediments

A

it allows, when waves come, to input MOP - particular organic material – food for organisms

18
Q

List the beach zones

A

sea
ante praia
zona arrebentação
surfzone
swash
face praial - intnertidal - zona espraiamento
linha de espraio
berm
pos praia
dunas

19
Q

Threats to Coastlines

A

Human actions (e.g., construction, sand movement Vehicle). overexploitation
Climate change (e.g., storms, temperature increase - turtles).
Seaweed removal.
Marine litter.
Microbial contamination
runoff and eutrophication

20
Q

dune formation

A

by wind that transport sand grains and deposits onshore (a bit can be from contribution of tides and waves)

it needs an obstacle for initial formation of a dune like a small dune – after this it can grow rapidly

21
Q

why is the north of portugal coast + exposed?

A

wind transport goes from north to south

22
Q

dune types

A

Pré-duna

embrionárias ou pré-duna

dunas frontais, primárias, móveis ou brancas

Yellow dunes (primárias)

grey

maturas

pós dunas

23
Q

areas entre dunas

A

interdunas

 Plane with depressions between dunes.
 Higher moisture and protection leading to increased biodiversity

24
Q

dunas mais expostas têm caract

A

ph alcalino
alta salinidade
moveis
dry

25
Q

Post-dunes used to help in special planning

A

yes because it offered protection to urban areas

26
Q

Threats to Dunes

A

o humanos – veiculos, caminhar, infraestruturas, lixo, corte de vegetação, extração de sedimentos
o pouco mov de sedimentos
o alt clima = + tempestades = + mov de sedimentos

27
Q

solution to Threats to Dunes

A

paliçadas – osbstáculo que aumenta a acomuação de areia = nova duna

  • atividade humana
  • casas a beira mar
  • passadiços
28
Q

qual areia é mais estável

A

fina

BC (5 decks)

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