Coastal Flooding Flashcards
Factors Increasing Flood Risk
Local factors increase flood risk on some low-lying and estuarine coasts due to
Height of land
Degree of subsidence
Vegetation removal
Global sea level rise further increases risk
Densely populated coastal areas also increase the number of people at risk
Low-lying coastal areas are often densely populated due to:
Attractive scenery and beaches
Deltas are fertile and ideal for agriculture
Suitable for ports and trade
Globally, almost …………million people live in coastal areas below 2m
300
Bangladesh over ……% of the land is 1m or less above sea level
10%
Height of land
Low lying areas are more vulnerable to rising sea levels and storm surges
Storm surges and spring tides leads to water flooding areas of the back-shore and beyond
What factors increase subsidence(grounds sink)
Coastal areas are vulnerable to subsidence particularly deltas and land reclaimed from the sea
Clearing land for agriculture and ground water abstraction, increases the risk of subsidence
Building of settlements, along with the weight of the buildings, increases the risk of subsidence
When subsidence occurs, the land is then lower and more vulnerable to coastal flooding
Vegetation removal
The removal of vegetation, including
salt marshes and mangroves, increases coastal flood risk
It is estimated that 50% of salt marshes and 35% of mangroves have been lost since the 1950s due
Reclamation for development - housing and transport
Coastal management such as sea walls
Tourism, to create beaches with open views to the sea
Shrimp farming
Where vegetation exists, it significantly impacts wave height, which reduces the risk of flooding:
In the UK, salt marshes are estimated to reduce wave height by up to ……………%
80
The vegetation
Traps sediment, which helps to increase the land height
Reduces the impact of waves and erosion because, it absorbs the wave energy
