Nile delta case study Coastal recession caused by humans Flashcards
What is delta?
Depositional landform built with sediment brought down from the Nile when it floods.
How did construction of the Aswan high dam impact river discharge?
River discharge fell from 35 billion tons of sediment to 10 billion after the construction of the dam. This caused sediment volume to fall from 130 million tonnes to 15 million tonnes.
What caused these changes?
Water withdrawals for industry such as farming or cities
Sediment was trapped by the dam and deposited in the reservoir
What effect has the construction of this dam had on erosion rates at Rosetta?
Erosion rates rose tenfold from 25m to 200m
Where is the Akosombo dam?
In Ghana
Why did the Akosombo damn increase erosion?
Minimised the supply of sediment allowing erosion to dominate
Togo and Benin are also affected as they have no other supply of sediment
1300m breakwater built around Lome trapping sediment
These countries cannot source any funds for coastal defence
Where is Guinea-Bissau?
In West Africa
What are the reasons for increased rates of erosion in Guinea-Bissau
- Gravel collection
- The removal of vegetation
- A construction boom
- Poor coastal management
Where are Mangrove forests often found?
They are found on coastlines and are good natural barriers to erosion
Why are the Mangroves being removed?
Fuel wood is needed to cook food
What is gravel and sand collection for?
Can be extracted for gold and diamonds and can be mixed to make cement for construction of local mud houses
