Coasts - Session 6 The Nile Delta – a product of a low energy environment.

Starter What conditions are necessary for a delta to form? You should have Large fluvial loads entering the sea Broad continental shelf margin Low wave energy Low tidal range

The Nile Delta This image shows Egypt at night as taken by the International Space Station. What does it suggest?

What can you learn from this diagram? The Nile Delta What can you learn from this diagram?

Rosetta Promontory Mouth of the River Nile

Rosetta promontory - result of deposition where the Nile enters the Mediterranean. NW winds mean that the promontory is exposed to incoming waves = erosion Longshore drift and ocean currents carry eroded sediment to the east along the outer edge of the Delta Leads to deposition. In the past = growth of the spits / bars across the Burullus lagoon. Today – the NW facing beaches are being eroded again (lack of sediment from the Nile means erosion exceeds deposition. This sediment is moved and deposited in the more sheltered water around Gamasa.

Similar situation around the Damietta Promontory: Built up by deposition of fluvial sediment (alluvium) by the Nile Eroded as faces the NW winds Material transferred east to build up the spits / bars across the Manzala lagoon – although now eroding. Along the whole coast line, on shore winds have blown sand inland to create the sand dunes Growth of spits and bars has created sheltered water and allowed salt marshes to form

The Nile Delta What impact would the building of the Aswan High Dam have on the Nile Delta?

Changes over time Sea level rises have reduced the delta’s size over the last 4000 years Number of distributaries has reduced from 7 to 2 Lagoons and salt marshes have decreased in area Deposition used to dominate – the Rosetta and Damietta promontories have extended northwards into the Med sea over the past 4000 years Eastwards LSD and deposition to the east of the two main Nile branches has lead to the build up / growth of spits and bars which enclose the Burullus and Manzala lagoons. Today, the balance of processes has changed – erosion is now dominate due to: Aswan Dam has reduced the supply of sediment to delta – sediment in the Nile is now trapped behind the dam Sea level rise means the coastal edge (frontal plain) is being eroded Increased use / installation of coastal defences e.g. Rosetta promontory Increased erosion being seen on the seaward edge of the spits / bars surrounding the Burullus and Manzala lagoons.

Coasts – Session 6 Key questions What characteristics do low energy coastal systems have? Which landforms do we associate with low energy systems? The Nile Delta is the product of a low energy coastal system. To what extent is this true? How do human factors shape low energy coastal environments?