Includes the case studies: low energy costal environment (Nile delta), high energy coastal environment (Flamborough Head Yorkshire), intentional management impacts along coastline (Holderness York), unintentional management impacts along coastline (Dubai), carbon and water cycle (Amazon rainforest)...
Coastal Landscapes
Low energy coastal environment – the Nile Delta
The Nile delta in Egypt has an area of 12512 sp km and has been formed
from deposition of the Nile River which runs for 6650km.
The Nile River runs through the capital of Egypt, Cairo as well as Memphis
and Aswan.
The river is the main input into the Mediterranean Sea as the area has very
low winds which minimises fetch and wave energy input.
A large proportion of the Nile River flow originates from Ethiopia and its
summer monsoon rains. Due to the high temperatures in Egypt and Ethiopia,
a lot of water carried in the river evaporates by the time the river reaches the
sea meaning the river has a low discharge but large sediment load.
The delta is an arcuate delta meaning it has the potential to grow seawards
but wave action trims the edges giving it a smooth round shape.
The many distributaries running through the delta help with the constant
supply of sediment.
Longshore drift occurs to the east which has created landforms such as the
Damietta spit and the Rosetta spit. There is also a sand beach between
Damietta and Rosetta with a length of about 160km.
This beach cuts off a large lake (Lake Brollos) and other small ponds.
There is also an offshore bar that’s formed between Damietta and Pelusium
due to the deposition of sediment from the tributaries leaving the delta.
These landforms change seasonally as average surface current velocity is
much lower in the summer than the winter.
Humans have affected the delta by the construction of the Aswan damn
which has created imbalance between two major forces acting on the delta:
erosion and accretion.
As some sediment is deposited in the lake further up the river, this reduces
the sediment load so there is less supply to the delta and it begins eroding.
Has caused accelerated rates of erosion and rates of coastal retreat of up to
148m/year.
Indirectly, humans have affected the delta through global warming. The
increase in sea levels has lead to higher erosion rates as deeper water
produces larger waves with higher amounts of energy that reach further
inland.
High energy coastal environment – Flamborough head, Yorkshire
The 60km long coastal environment between Saltburn and Flamborough head
has many coastal landforms which reflect the influence of the high wave
energy it receives.
, The adjacent North York Moors consist of mainly sandstones, shale’s and
limestone’s formed during the Jurassic Period.
Flamborough head at the south of this stretch of coastline is a large chalk
headland whose cliffs are topped will glacial till left behind by glaciers from the
Devensian ice age.
The dominant waves affecting this coastline are from the north and northwest
with a fetch of over 1500km.
Most exposed parts of the coastline are those north facing such as the area
nearest to Saltburn as these receive the highest inputs of wave energy.
Rates of erosion vary due to differences in wave energy inputs and variations
in resistance of the different geologies.
Longshore drift movement is from north to south.
Sediment is supplied by cliff erosion.
River Esk is the fluvial input of sediment but the supply is limited due to the
construction or weirs and reinforced banks along its course.
There has been a net increase in beach sediment of 9245 square metres
between 2008 and 2011 at Saltburn.
The sedimentary rocks of this coastline tend to be horizontally bedded which
produces steep cliff profiles (vertical face) but the layer of glacial till has a
much lower angle.
Vertical cliffs are 20-30m high with the overlying till lowered by mass
movement processes to angle of about 40 degrees.
High energy wave sand active erosion mean that cliffs are retreating along
this coastline leaving behind shore platforms. Good example of this at Robin
Hood’s Bay.
The variation in rock type has resulted in a discordant coastline. The
prominent headland at Flamborough head is formed of chalk with deep bays
either side formed from clay.
Over 50 geos formed along this coastline with most of them aligned NE or
NNE facing the dominant wave direction.
As a result of wave refraction, caves, arches, stacks and stumps have formed
(clearly visible at Selwick’s Bay)
Few well developed beaches along this coastline – deposits of shingle and
sand accumulate slowly due to sediment input from rivers and slow rates of
erosion of resistant rock. High energy wave remove sediment before it can
accumulate. Although longshore drift is considerable, the coastline lacks drift-
aligned features due to the high tidal range of 4m.
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