Coast Flashcards
Contructive wave characteristics
Swash - strong ; weak
Backwash - weak ; strong
Wavelength - long with low height ; short with high height
Frequency - low ; high
Longshore drift
It is the main process of transportation along the coast
Influenced by the prevailing wind, waves approach the beach at an angle As the waves break, the swash carries material up the beach at the same angle As the swash dies away, the backwash carries the material down the beach at right angles (90°)
The process repeats, transporting material along the beach in a zig-zag movement
Headland features
Cliffs along its sides
Projects out to sea
Usually longer than it is wide
Geology is of resistant rock
Bay features
A wide, open entrance from the sea
A roughly, semi-circular shape extending into the coastline
Land that is lower than the headlands surrounding it
Case study coasts
Typhoon Haiyan - Philippines
Relief - the UK and USA sending diggers, land rovers and heavy lifting gear,The European Commission released $4m in emergency funds
Social Impacts - ST - 6201 people died,1.1 million homes lost; LT - 2 months later, 21,000 families were in 380 evacuation centres
Economic - ST - Estimated at $13 billion,Major sugar producing areas were destroyed; LT - more than 20% of government revenue spent on foreign debt repayments
Environmental - ST - Loss of forests/trees,Oil and sewage leaks; LT - An estimated 90 per cent of the rural population in typhoon-affected areas small scale farmers
Beach creation
sand from offshore bars can blow onto the shore by strong winds
Blown sand can create sand dunes
Spit formation
occur when there is a change in the shape of the coastline
Or the mouth of a river, which prevents a spit forming across the estuary
A bar
a spit grows across a bay, and joins two headlands together
Tombolo
A tombolo is formed when a spit joins the mainland to an island
Formation of a sand dune
sand is deposited against an obstruction - pebble or driftwood
As more sand particles are caught, the dunes grow in size, forming rows at right angles to the prevailing wind
Over time, the ridges of the dunes will be colonized and fixed by vegetation in a process called succession
Coral reef distribution is based on
Temperature
Light
Water depth
Salinity
Factors affecting coral reef development
Wave action - corals need well oxygenated, clean water and wave action provides this
Exposure to air
Sediment
Where do salt marshes form
Costal areas that are well sheltered, such as inlets and estuaries where fine sediments can be deposited
Areas behind spits and artificial sea defences where tidal waters can flow gently and deposit fine sediments
They form in brackish water
Characteristics of mangroves
They’re trees that live on the coastline
need high levels of humidity (75 - 80%) and rainfall per annum (1500 - 3000
mm)
Ideal temperature is around 27° C
Coastal opportunities
Tourism
Swimming and sports
• Industry
• Fishing
Agriculture
Coastal hazards
Storm surges
Storm tides
Tsunamis
Sea level rise
Tropical storm impacts
Destruction of buildings and infrastructure
Heavy rainfall and storm surges
Loss of ecosystems, trees, land, crops and animals
Managing tropical storms
Sea walls and levees
Evacuation plans for the population
Satellite tracking and early warning systems
Soft engineering
Beach replenishment
Fencing
Cliff reedging
Managed retreat
Beach replenishment adv and dis
Ad - absorbs wave energy and widens beach front
Dis - has to be repeated regularly which is expensive
Hard engineering coasts
Sea wall
Groynes
Rip rap
Sea wall ad and dis
Ad - Most effective at preventing both erosion and flooding
Dis - very expensive, ugly to look at, restricts access to beach
