Coastal Landforms Are Inter-Related In Low Energy Coastline Flashcards
Where is this coastline?
The Rhone Delta, France
How long has the delta been forming for?
Past 7000 years since sea level rise
What happened in the 18th century?
A flood moved one of the channels, meaning sediment at mouth moved forming Beauduc Spit
What happened in the 19th century?
Mouth changed position because human management made three channels into one
What is the total length of the delta?
90km
What is the area of the delta?
1740km
What dominates the delta? (2)
Waves
LSD deposits
What sea does the river Rhone go into?
Mediterranean Sea
What are the two places the delta is between?
Grande Rhone
Petit Rhone
What percentage of river water does the Grande Rhone take to the sea?
85%
What are the four characteristics of a low energy zone?
Enclosed shape = short fetch
Low wind speeds
Low wave height and energy
High sediment accumulation
How many tonnes of sediment on average were deposited in the delta in 1990?
50 tonnes/min
How many tonnes of sediment was deposited in total in 2000?
1.5 million tonnes/year
Why was the delta managed in 2000?
Prevent flooding and for HEP
Why is accumulation so high in the delta?
Low tidal range (0.3m)
Mediterranean sea is very saline > flocculation
What landform comes from the SW-NE LSD?
Gracieuse spit across Port St-Luis at Marseilles
What do converging LSD currents form?
Onshore bars
LSD moves sand behind onshore bars and spits what does this form?
Lagoons / etangs
What kind of plant species colonises dunes?
Marram grass
Name two features of marram grasses
Long roots to stabalise
Adapted to saline conditions
How are dunes formed?
Wind from sea moves dry sand through saltation, trapped by berms or obstacles, colonised by plants
What are the two categories of recent changes?
Erosion
Coastal Retreat
What is the average sea level rise since 1950?
2mm/year
What is the average retreat of the delta and where is it most noticeable?
2-8m
Stes-Maries
How much did authorities spend on coastal protection?
15 million euros
What is the largest fetch and where does it come from?
900km
SW
Why is coastal retreat happening?
Increased storm activity
Reduced river input
What type of management is there?
Riprap
Groynes
Sea walls
