COASTAL LANDSCAPES AND
CHANGE CASE STUDIES
Nile Delta
The Nile Delta is a depositional landform formed from sediment brought down the Nile by annual
floods – this shows river transported sediment can be extremely important to maintaining dynamic
equilibrium between erosion and deposition at the coast.
Area involved:
Located in North East Africa, where the Nile enters the Mediterranean Sea in Egypt
Intensive farming area and attracts large tourist numbers
39 million call the Delta home
What is the Aswan High Dam?
Built in 1960s
World’s largest embankment dam
Aim was to increase hydroelectric power provision and increase water for agricultural
production
1,100km upstream from the Delta
What issues does the dam cause?
Sediment volume dropped from 130 million tonnes to about 15 million tonnes
Limited natural seasonal flooding of the Delta – this was responsible for depositing rich,
fertile sediments on river banks
Increasing sea levels increasing the salinity of the Delta, decreasing it’s fertility and affecting
agricultural livelihoods
Cities along the Delta are under threat from rising sea levels, offshore bars are being eroded
and 3.3% of the land will be lost
Erosion rates at the Rosetta just from 20/25m per year to over 200m a year as the delta was
starved of sediment
How has the dam caused these issues?
Water withdrawals for industry, cities and farming from the reservoir behind the Aswan High
Dam
Sediment being trapped by the reservoir and dam, water in the reservoir flows very slowly
allowing sediment to be deposited
Bangladesh – coastal flooding and storm
surges
Area involved/causes of flooding:
, - Bangladesh lies on the floodplains of 3 major rivers (Brahmaputra, Ganges, and Meghna)
which all converge in the country. There are also 54 smaller rivers that flow into the Bay of
Bengal through a series of estuaries.
- Almost every year, huge areas of the country flood as Himalayan snow melts adds to
monsoon rains (which are worsened by climate change) and high tides in the Bay of Bengal
- Between March and May, violent thunderstorms produce strong southerly winds of
160km/h which can bring 6m high waves from the Bay of Bengal to swamp coastal areas.
- Deforestation is also to blame, causing soil erosion, which reduces the ability of the land to
absorb water.
- Irrigation for farming causes river channels to silt up, reducing capacity to hold flood waters
Subsidence in Bangladesh:
Some of Bangladesh’s estuarine islands have sunk by as much as 1.5m in the last 50 years.
Isostatic readjustment is partially responsible, but the main reason is the clearance and
drainage of more than 50 large islands in the Ganges-Brahmaputra River delta.
Embankments:
Over the last 50 years, Bangladesh has built 4000km of embankments along the coasts.
Around 30 million people live on polders (land enclosed by embankments).
In 2014, Bangladesh was planning to spend $400 million from the World Bank to upgrade
these embankments.
However, this intervention by humans has prevented the natural deposition of sediment
used to maintain the island’s height – and therefore islands are fast submerging.
Mangrove Protection
Mangroves helped protect areas from coastal flooding in 2007 when Cyclone Sidr struck
However, since then, satellites show that 71% of the forested coastline has retreated by
200m/year, removing the country’s natural protection barrier
The causes of this area: rising sea levels, erosion, deforestation.
CYCLONE SIDR, 2007 -
In November 2007, tropical storm Cyclone Sidr struck the south-west of Bangladesh with winds
reaching 240km/h and a storm surge of 6m hitting the Bay of Bengal. The surges breached coastal
and river embankments, flooding low-lying areas, and causing extensive physical destruction.
Impacts:
High winds and floods also caused damage to housing, roads, bridges, and other
infrastructure.
Electricity and communication were knocked out, and roads and waterways became
impassable.
Drinking water was contaminated by debris and many sources were inundated with saline
water from tidal surges, and sanitation infrastructure was destroyed.
Death toll over 3,000
Cost estimated at US $1.7 billion
