salt marsh - blackpoolsixthasgeography

advertisement
WHY
The Essex coast makes up about 8% of the English
coastline with over 80% designated as sites of Special
Scientific Importance. This coastline is vulnerable to
erosion with increasing pressure from Global warming
and the settling of the South East due to Isostatic
readjustment causing a sea level rise of 6mm per year,
increasing the erosion of the coastline and encouraging
coastal squeeze. The flood defences were also coming
to the end of their effective life and needed replacing
to continue their protection of the coastline.
COASTAL SQUEEZE
Area Squeezed
50% lost in 25yrs
Erosion of Mudflat and Salt marsh
Sea Wall
Prevents
Migration
Mudflat and Salt marsh areas
migrate inland, reclaiming land
Erosion of Mudflat and Salt marsh
POLDERS
A polder is an area around the estuary which is fenced off to encourage
deposition of sediment. There are 26 polder sites along the Essex
Coastline. This fence is made of willow hurdles which increases the
sustainability of the project.
Polders encourage the development of the salt marshes as the fences
reduce the energy of the waves which allows the build up of sediment and
the encourages the establishment of plants through calmer waters.
As the salt marsh develops, the polders decompose, reducing negative
visual pollution created through the fencing. These polders are ideal
environments for birds such as herons and red shanks reducing the
environmental impact of other sea defences.
Abbotts Hall Farm is a 700 acre farm on the Salcott Channel of the Blackwater
Esturary. In the last 25 years 50% of saltmarsh has been lost to the sea along the Essex
Coastline. At Abbotts Farm Hall the sea wall was deliberately breached in October
2002. This was to encourage the growth of salt marshes onto 300 acres of Abbott Hall
land originally reclaimed by the construction of the sea wall over 3000 years ago.
The breaching of the sea wall was timed to precede spring tides, allowing each tide to
float in seeds from the existing marsh outside the breached wall. By midsummer,
thousands of new salt marsh seedlings were covering the fields. The development of
81 hectare of mudflat, pioneer salt marsh and coastal grassland had begun.
The pressure on sea walls elsewhere along the
Blackwater Estuary have been reduced
£500, 000 has been saved in sea defences
A natural defence against flooding has been created
New wildlife habitats, i.e. inter-tidal mudflats and
salt marshes have been created
DISADVANTAGES
ADVANTAGES
Salt marsh, which is rare in Europe is flourishing
A certain amount of land will inevitably be lost in this
process while beaches are being built up.
Settlements, farmland and other property is
destroyed.
There is a need for compensation to land-owners.
It may interrupt communications so new roads and
pipelines might need to be laid.
Download
Related flashcards

Polynesian languages

33 cards

Islands of Africa

14 cards

Islands of Vanuatu

45 cards

Islands of France

17 cards

Create Flashcards