- Created by: hannah morten
- Created on: 03-01-17 20:22
Case studies coast
Rapid coastal recession is caused by physical factors but can be influenced by human actions.
The Nile Delta
· 240km long coast
· There are holiday beach resorts, coastal defences, general tourism, marine recreation, fisheries, land reclamation, agriculture, settlements, transport and port infrastructure.
· There is salt intrusion into the delta due to climate change. As sea level rise and protective offshore bars are eroded, 3.3% of the delta land area will be lost.
· The building of the Aswan Dam in 1964 reduced terrestrial sediment supplies.
· A 2015 study classified 32.4% of the Nile Delta coast as highly vulnerable with only 26% as low vulnerability.
· If sea levels rise by 1m by the end of the century and no action is taken, 2 million hectares of fertile land will be lost and at least 6 million people displaced including about 30% of the city of Alexandria.
· In the past 50 years Bangladesh has built 4000km of coastal embankment. About 30 million people live on polders (land enclosed by embankments).
· In 2014 Bangladesh was planning to upgrade 600km of embankments in the Sundarbans delta region (using $400 million from the world bank)
· However there is an argument that this would do more harm than good and the embankments constrict and funnel tidal flows, pushing water further inland and increasing the tidal range: the polders should be abandoned and the embankments positioned further back from estuaries to reduce this effect.
Local factors increase flood risk on some low lying and estuarine coasts; global sea rise further increases risk.
· Most densely populated country:169 million in 2015
· 46% of the population lives less than 10m above sea level
· Lies on the flood plains of 3 rivers, which all converge in Bangladesh.
· Himalayan snow melt
o Estuarine islands sunk by 1.5m in the last 50 years.
o Due to clearance and drainage of more than 50 large islands in the Ganges- Brahmaputra river delta
o These islands used to be forests but have since been cleared for farming of rice to feed
o Embankments were built for protection, but they stop natural deposition that used to maintain the islands height
· Removing vegetation
o 71% of Bangladesh’s mangrove forested coastline is retreating by 200m a year.
Storm surge events can cause severe coastal flooding with dramatic short-term impacts.
· Cyclone Sidr came in from the Bay of Bengal on the 15 November 2007, bringing with it a storm surge that reached up to 6m high in some places.
· It brought with it very heavy rain and winds of up to 223km/h.
· A category 4 storm
· According to Bangladesh Meteorological department, the eye of the storm crossed the coast near Sundarbans mangrove forests around 9.30om.