Fichas
Morpho exam 1
Fichas del conjunto (105)
- 1Main hydrodynamic agents1 Waves
2 Currents
3 Sea level - 2—
- 3Oceanic RidgeDivergent plate boundary
New oceanic crust is produced
No sediment layer at surface - 4Abyssal plainFlat area
sedimentary accumulation
(remains from living organisms & fines from continents) - 5Seamounts1 km height in abyssal plain
do not reach surface
volcanic origin - 6oceanic trenchdeep and steep slope
created by subduction
convergent boundary - 7Continental margin include?- Continental Shelf
- Continental slope
- Continental rise - 8Active continental marginsubduction trench
narrow continental shelf - 9Passive continental marginNo subduction
wide continental shelf with thick accumulation of sediment - 10—inner shelf: waves act on seabed
middle shelf: transition zone
outer shelf: not affected by waves
- 11sediment (sand or silt?) inner shelf: .... outer shelf: ....inner shelf: sand (rough)
outer shelf: silt (fine) - 12InterglacialHigh sea levels
- 13glaciations - Ica AgeLow sea levels
sediment reaches continental slope
Sand/ Gravels deposit that will become relict during next interglacial. - 14sand ripples formed by a. b.a. waves
b. current (directed to the right)
- 15tidal deltasand deposit at the entrance of lagoons and river mouths
- 16rocky reefs are formed by: 1. 2. 3.1. erosion (wave, sea level rise)
2. Coral reefs: colonies of polyps held together by Calcium.
3. Calcium precipitation (beach rocks) - 17Antrhopogenic features (human activities)1. Seabed resource exploitation (sand/gravel extraction -> pits)
2. underwaterstructures for coastal protection (wave breakers)
3. devices for energy production (wind farms)
4. navigation safety (channel dredging) - 18A wave transports ...energy
- 19Different wave types (from small to large frequency)Gravity waves:
1. tidal waves
2. long-period waves
3. windwaves - 20Wave basewater depth that is reached by orbital motions
= 1/2 of wavelength (L)
- 21Significant wave heightHs (m)
average of the highest (33%) of waves for a given period - 22Maximum wave heightHmax
maximum value observed for a given period - 23periodT (s)
Tm: mean period
Tp: peak period (considering highest waves) - 24Directiondirection from which the waves are coming
Dm: mean direction
Dp: peak direction - 25Wind waves- Locally generated by wind
- short period (and wavelength)
- Highly variable in shape (due to wind variability) - 26Swell- Generated remotely
- Large period (>8s) and wavelength
- weak variability - 27Size of waves depend on:1. wind speed
2. wind duration
3. Fetch - 28FetchUnobstruted distance over which the wind blows
- 29Fully developed sea, when: - -- wind blows continously for 3 days
- maximum wave height is obtained - 30Wave dispersionWaves with different period (or wavelength) travel at different speed.
- 31Dispersion equationwave speed (c)
c = gT / 2pi
Waves with long wavelength travel faster - 32Wave groupwave group speed (Cg) in deep water
Cg = Cw/2
where Cw = individual wave speed - 33wave group out of phase / in phase
- 34Waves shape entering shallow water
- 35Deep water regimed > L/2
Cinf = gT / 2pi
cg= cw/2 - 36intermediate water regimeC = gT/2pi * tanh (2pi d/ L)
- 37Shallow waterCs = sqrt( g d)
cg = cw - 38Energy of a wave equation
- 39Power of a wave equationP = E Cg
- 40Wave refractioncauses energy to concentrate on headlands (erodes them)
- 41Wave diffraction
- 42spilling wave
- 43plunging
- 44collapsing
- 45Surging
- 46Spring tide: Neap tide:Spring tide: Large A, full moon
Neap tide: Low A, lunar quarters
tidal waves are horizontally! - 47diurnal tide1 tide per day
- 48semidiurnal tide2 tides per day
- 49mixed tideboth diurnal and semidiurnal ( one is dominant )
- 50Storm surgeabnormal rise of water due to a storm
extreme flooding when coincides with spring tide - 51Coastal protections 1. 2. 3.1. hard structures (seawalls
2. Soft engineering (use of natural process)
3. Hybrid methods (mix of 1 and 2) - 52Data in the field can be collected by?- Boats
- Seabed moorings
- Buoys
- Drones
- Satellites - 53Bathymetry single beam echo-sounder (1m res.)
- 54Bathymetry Multi beam echo-sounder (few dm res.)
- 55Bathymetry LIDARLight detection and ranging
very expensive
- 56Seabed constitution Side scan sonaracoustic image of sea.
combined with sediment sampling.
- 57Hydrodynamics Wave buoysfollow the movement of ocean surface
give (Hs, period, etc)
multi-parametric buoys give aswell current, T, S etc.) - 58Hydrodynamics Pressure sensorsMeasure the pressure
1 bar (0,1atm) per 1 meter of depth - 59Hydrodynamics Tide Gaugemeasure sea level
- 60Hydrodynamics current metersmeasure the current at one location
(velocity and direction)
ADCP = acoustic doppler current profiler
- 61Hydrodynamics Surface driftersFree floating bouy to monitor:
S, T and currents - 62Sediment dynamics Turbidity metersMeasure suspended sediment concentration
- 63Sediment dynamics Sediment traps: Sediment tracers:Sediment traps:
to catch sediment
Sediment tracers: paint sediment
- 64Sediment sourcesrivers
volcanoes
wind
erosion - 65bedloadcoarse sediment transport (sand, gravel)
in river - 66suspended laodfine sediment (silt, mud) tranpsort in river
- 67longshore transport (Q)along the coast
typically between 0,2 and 1 m/s - 68cross-shore transporterosion and transportion perpendicular to coastline
- 69sediment transport depend on- Hydrodynamic agents: wave, current, water level
- water depth
- grain size - 70—
- 71surf zonewhere the waves break
- 72swash zonewhere waves run up the beack after breaking
- 73What to know about LST formula?-results vary widely
-large uncertainties - 74cross-shore beach profile difference between summer and winter
- 75Cross-shore current: undertowcompensates for onshore-directed transport of water by waves
- 76rip current
- 77Depth of closure (DoC)limit of active coastal zone
depth at which there is no significant morphological change - 78coastal area- where interactions of sea and land processes occur
- land and sea, forming a continuum - 79—
- 80types of coast based on: - erosion - rock composition - hydrodynamic forcing - morphology
- 81Depositional coastlot of sediment
deltas
barrier islands
beaches
- 82erosional coaststeep, irregular
no beach
cliffs
sea stacks
- 83submergent coastsea-level rise
depositional
large bays
estuaries
barrier islands
lagoons
- 84emergent coastsea-level fall
erosional
small bay
rocky coastline
- 853 different corral reefs where are they formed?Fringing reefs: along coast lines
Barrier reefs: offshore, seperated from land by a lagoon
Atolls: upward coral reef growth on margins of a volcano that has been submerged
- 86Rocky reefsuplift (volcanic activity / tectonics / melting of glacial ice)
form where wave action had no time to erode
- 87—
- 88wave erosion notch
- 891 2 3cave arch stack
- 903 major theories formation of Barier island1. Dune drowning
2. Spit accretion
3. Shoal emergence - 91flood and ebb delta
- 92jettiesstop LST
decrease bypass
- 93Tidal prismvolume of water entering/leaving lagoon during flood or eb
- 943 forcings influencing a Delta1. sediment input (river dominated)
2. wave energy (wave dominated)
3. tidal energy (tide dominated)
- 95upper and lower limitupper: vegetation line
lower: depth of closure - 96—
- 97beach cusps
- 98Relative tidal range (RTR)RTR = MSR/ Hb
Hb = waveheight at breaking
MSR = mean springtidal range
RTR >= 15. shoaling processes dominate and swash and surf are unimportant - 99infragravity wavessurf bea: 2-3 min
- 100wave setupsea level elevation between breaking zone and beach
η ~ 0.2 x Hs
- 101run upuprush limit of the water level
Run up = setup + swash
- 102overwashcoastal flooding produced by waves overtopping the sand dunes
- 103washoversediment deposit by overwash
- 104dissipative and reflective beach
- 105sediment budgetquantification of sediment volumes enetering and exiting a region
Accretion V Erosion
Información
- Descripción
- Treinador Interno Morphodynamics Fichas sobre Morpho exam 1, creado por renske koets el 08/11/2022.
- Creado por
- renske koets
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