Coastal Hazards Flashcards
definition of coast
is where the land and sea meet, and goes 50km back inland
what is a coastal hazard model?
source, pathway and receptor model
social aspects of coastal hazards:
fatality by gender/age, deprivation correlation (both local and country scale)
what causes changes in sea level?
tides or wind (movement), glaciation (add or subtract), global warming (properties) and tectonics (basin volume)
what is glacio-eustacy?
global sea-level changes resulting from terrestrial ice-volume changes
what is glacial-isostacy?
process by which the earth’s crust seeks to reach equilibrium following loading or unloading by ice
what are local changes that contribute to sea level rise?
subsidence (due to sediment weight) and tectonic control
what are impacts from sea level rise effects?
inundation and loss of land and rising groundwater
what are coastal retreat processes?
erosion occurs when the beach is out of equilibrium (Bruun rule/equation), barrier translation (coarser material migrating shoreward) and barrier overstepping (a large event causing barriers to be moved)
what are options to deal with coastal retreat?
do nothing, managed realignment, hold the line and limited intervention
characteristics of a tropical cyclone
form over large, warm bodies of water, between 100 and 4,000 km in diameter, energy from ocean surface evaporation and considered a cyclone when reaches 120km/h
characteristics of a extra-tropical cyclone
known as depressions/lows, formed by horizontal pressure contrasts and form within extra-tropical regions
what is a storm surge?
a rise above the normal water level along a shore resulting from reduced atmospheric pressure and strong onshore winds associated with a storm
what are the pre-requisites for tropical cyclone formation?
large, still warm ocean water (exceeding 26.5 degrees). low altitude winds blowing from different directions
what are the pre-requisites for extra-tropical cyclone formation?
large horizontal, near surface temperature gradient. strong winds in the upper troposphere (jet streams)
what are some climate controls on cyclone activity?
ENSO circulation (surface temperature warming globally, forming more common cyclones) and climate change impacts increasing cyclone and storm frequency/intensity
where are the largest drowning statistics from? why?
central Africa, Bolivia, Afghanistan due to cultural context leading to lack of training and experience
what are the types of bathymetric rip currents?
channel rips and focussed rips
when are rip currents at high risk?
low tide and when wave height increases
how to manage rip current risk?
awareness, education, signage, rules and regulations
what are tsunamis?
a large wave, or series of waves, caused by catastrophic displacement of water (a type of wave generated in a non-standard way)
what are the four events that could cause a tsunami?
earthquakes, landslides (subaerial and submarine), volcanoes and asteroids
where do tsunamis occur?
within the ring of fire - 60% within the Pacific ocean and a lot in the Mediterranean sea
what are mitigation and evacuation practices for tsunamis?
sea walls, floodgates, pacific tsunami warning system, evacuation zones, training of locals and maps
what are the short-term impacts from a tsunami?
land submersion, broken infrastructure (hospitals), fatalities, displacement, failed warning system, disease spread, salinity impacts (soil salination), and aid (wells etc.)
what are the medium-term impacts from a tsunami?
river geomorphology and ecosystems change, estuarine system change (saltwater limit, sediment supply and river mouth location) and coastal retreat
what are the long-term impacts from a tsunami?
uplift in water and land e.g. reefs, causing a long recovery time
