2b - (The Nile Delta) Coastal landforms are inter-related and together make up characteristic landscapes

Question 1

key physical factors influencing a low-energy coastline (fluvial/aeolian)?

Answer 1

• two distributaries (Rosetta and Damietta) of the river Nile are the main sources of sediment
• the Nile is split it has less energy so more deposition occurs
• LSD east-west side is more vulnerable - delta retreating 148m a year
• dry sand from beach = Gamsa dunes

Question 2

key physical factors influencing a low-energy coastline (wave energy)?

Answer 2

• low, less erosion, short fetch = constructive
• build up beaches (small tidal range)
• LSD occurs from west to east do there are drift-aligned beaches, spits and barrier bars. (steady, constant, slow change)

Question 3

key physical factors influencing a low-energy coastline (sediment supply)?

Answer 3

• sediment being stopped by the dam, more erosion (1964) = landforms are in neg sed budget (120mill tonnes/yr sed - basically nothing)
• clay, silt, fine sand - not very resistant to erosion = build up the banks/beaches from constructive waves

Question 4

key landforms of a low energy coastline

Answer 4

• Damietta onshore bar- formed lake Manzala - the largest lagoon in Egypt.
• Lake El Bullurus (Burullus Lagoon) - its saltwater and only 175cm at deepest point
• Sabkhas- LSD forms bars across a lagoon. when the water evaporates salt flats (Sabkhas) are formed.
• Gamsa sand dunes - developed between Manzala and Bullurus
• Crescentic bars at Alexandria - formed by rip currents and onsure waves with little LSD

Question 5

how the landforms in a low energy coastline could be interrelated?

Answer 5

• Damietta headland shelters = less wave energy = increased deposition - sed for damietta bar formed through LSD. The Damietta on-shore bar forms, cutting off the sea and forms Manzala lagoon and protects it from the sea. water evaporates from the hot weather forming a sabkha
• Sediment from the crescentic bars at Alexandria originally came from the distributaries to form the bar, sediment was moved by aeolian processes to form Gamsa sand dune. overtime = reduction in sed = smaller beach = less sandune (are good protection for SLR)

Question 6

how could the landscape change over time in a low energy coastline (Damn)

Answer 6

• the Aswan damn since 1964 is restricting the sediment supply to on-shore bars (mouths eroded Damietta = 36m/yr and Rosetta = 24m/yr ) so they won’t get bigger
• The damn also means that less sediment will get to the crescentic bars at Alexandria.
• ensure water supply to growing pop, hydroelectric power
• loss of fish farming and economic potential, degrigated agricultural land - less fertile

Question 7

how could the landscape change over time in a low energy coastline (climate change)

Answer 7

• due to the rising sea levels, the bars may be breached and sediment may be lost to aeolian processes as its dries quicker so is lighter.
• Lagoons may become smaller as some sediment from bars is blown into them.
• SLR - 1.2mm/yr = increased erosion as deep water = larger waves = more energy reaching inland, increased retreat = less land for human habitation
• As sea levels rise the lagoons could flood and delta inundated with sea water - socio economic impacts (60% loss of farmland by 2100, loss of drink water)

Question 8

how could the landscape change over time in a low energy coastline (seasonal)

Answer 8

• In the winter winds blow to the west (dominant = 55-60%) but in the summer they blow to the east (8%) so sediment is moved differently throughout the year.