2B.9A Flood Risks And Storm Surges Flashcards
What is eustatic slr due to
Climate change making
Warmer oceans - thermal expansion
Melting ice caps / sheets at the poles
How long ago is considered contemporary
250 years
How does the height of land increase flood risk
Low elevation areas (estuaries and deltas) are more susceptible to coastal flooding
So storm waves and a higher sea level can more easily flood these features
Low-lying areas are also at risk of submergence
Why are some delta subsiding
Some deltas are subsiding due to increases in river flow washing their sediment out to sea others due to sediment starvation from dams
Why are some deltas subsiding and shrinking
Due to the increased building of settlements on the land
How do dams cause sediment starvation
There is less sediment flowing towards the delta, resulting in it being lower lying which will increase coastal erosion and flooding
How does dredging cause sediment starvation
Dredging removes material from the sediment cell meaning that there will be less beach material available to build up the beach which would dissipate wave energy
How does removal of vegetation place coastlines at higher risks of coastal flooding
Coastal species encourage deposition and stabilisation this makes the area less susceptible to flooding especially during storm surges
How do mangroves reduce coastal flooding
Reduce the height of the waves which reduces coastal erosion
Reduces storm surge levels
Their roots trap sediments raising the height of the coast
How does reclaimed land increase flood risk
The land sits at low elevation as reclaimed land is often below the sea level so seawater can easily inundate
The drained areas are no longer acting as natural flood defence barriers so they are unstable to absorb storm sugars so exacerbated flood risk
What is the combination of ocean acidification and rising sea temperatures causing and what is the effect
Coral bleaching and eroding coral reefs reducing their effectiveness at absorbing wave energy
What is a storm surge
A short term rise in. Sea level caused by high winds pushing towards the coast and by the low pressure of a storm
What can lower air pressure cause
Stronger wins to move across the sea and a storm urge may occur
What happens during a storm surge
Waves move onshore with greater force
Water builds up behind the crest of the waves making them taller and more likely to flood the land as they break
What does the bay of bengals unique shape mean for storm surges
The funnel shape and its many inlets and the flat low lying land areas that border it , causes larger storm surges and they can move more inland impacting the densely populated regions near the coast
