Sundarbans Coast Case Study Beyond UK Flashcards
(18 cards)
Describe the location and background of the Sunderbans
Coastal zone occupying the world’s largest delta.
Extends over southern Bangladesh and NE India
offers a wide range of vital ecological services (cyclone protection for millions of people, wildlife
habitat, food and natural resource provision, carbon sequestration).
Home to about 7.2 million people in total
What is a delta?
A lanfrom created when a river enters the sea, loses energy and deposits sediment (clay, silt, sand)
What are khals?
An interconnecting small channel connected to larger channels
What are the characteristics of the Sunderbans?
The Sundarbans are a series of many islands with mangrove forests and swamps.
Network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests.
Climatic climax are mangrove forests and swamps
Known for it’s wide range of animals including 260 bird species, Bengal tiger and other threatened species eg) estuarine crocodile
What are the features of mangrove forests?
Mangroves are a group of trees and shrubs that live in the coastal intertidal zone.
Trees that grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate.
Grow at tropical and subtropical latitudes near the equator as they cannot withstand cold temperatures.
A key feature are ‘prop’ roots: dense and tangled that make the trees appear to be standing on stilts above the water.
These roots absorb the energy of tropical storms.
Roots are adapted to salt water and the daily rise and fall of tides, means that most mangroves get flooded at least twice per day (Halophytes).
Coastal processes in the Sunderbans - Tidal action
The strong tidal current flows north at high tide and south at low tide twice a day.
This frequent movement of water creates large, straight channels that are 2km or more wide.
So the direction of large channels is north-to-south.
tidal action inundates the forest areas with sea water from the Bay of Bengal twice a day.
At low tide, all water drains from the forest areas.
This creates the extensive network of interconnecting smaller channels (khals).
Coastal processes in the Sunderbans - Erosion
Network of channels are made up of clays and silts
Clays and silts are extremely cohesive so quite resistant to erosion.
Prop roots of the mangrove forests dissipate energy creating low-energy coastal environments.
So reduces erosion from storm surges, currents, waves, and tides.
So the interconnected river channels remain static and rarely move.
Coastal processes in the Sunderbans - deposition
Mangrove forest prop roots slow the movement of tidal waters, causing sediment to be deposited and build up a muddy riverbed/seabed.
Non-cohesive sediment (sand) deposited on banks at the river mouths.
South westerly prevailing wind blows deposited sand into sand dunes.
These dunes the act as protection for fine sediment to be deposited further and over time, new islands are developed.
Over time, vegetation is established on these islands which leads to a climatic climax of mangrove forests.
Opportunities - goods
Mangroves provide timber for construction, firewood and furniture
Cargo ships transport goods such as oil and food in for people to buy and
trade
Rich ecosystem of mangroves provides the
local population with fish, crabs, honey and nipa palm leaves for roofing and basket making
Opportunities - services
Tourists want to visit mangroves and wildlife + also opportunities for education and to explore heritage of the area.
mangroves are perfect for breeding and fishing grounds. Also absorb
C02, mitigating climate change
Flat fertile land is ideal for growing crops, particularly rice
Mangroves protect against coastal erosion – the roots bind soil together
Mangroves are a natural defence against flooding; can reduce the destructive force of a tsunami or cyclone by up to 90%.
Risks - natural
Flooding - can lead to salinisation making it hard to grow crops. Soil salinity increased six times between 1984 and 2014
Area is affected by cyclones, there have been 13 supercyclones in the past 23 years
Dangerous animal attacks e.g. tigers- increased population / need for food is
leading to increased usage of the tigers’ habitat. Tigers killed 22 people every year between 1935 and 2006.
Risks - human
Growing population - more fuel and farmland needed, so mangroves being
removed. 2000-2020, 110km2 mangroves disappeared.
Low-lying land at risk from rising sea levels. Rising 2x as fast as the
global average and the area has lost
12% of its shoreline in the last 40 years
Access is difficult with few roads, many of are poor quality. Difficult for residents to receive goods, healthcare and education
Only 20% of houses have electricity which means communication is difficult
and many residents don’t receive flood warnings
Define resilience
The capacity to recover quickly from impacts / cope
Define mitigation
Taking action to reduce severity of impacts
Define Adaptation
Changing behaviour to become better suited to an impact
What are the human mitigation responses?
Protect and replant mangroves
Cyclone shelters and early warning systems
Communities can use open access natural resources eg) khas land (government owned land protected for use by local by populations wetlands, fisheries and forests
What are the human resilience responses?
Build roads and bridges to improve access
Training in sustainable fishing and farming - Fertile soils and ecological
diversity provides a plentiful supply of a large range of nutritious foods.
Forests have an economic value of over $12,000 per hectare even when only used for traditional activities (fishing, timber, seafood).
What are human adaptation responses?
Salt-resistant rice crops – using a new variety of rice that can be submerged in salt water for two weeks
Cyclone shelters are becoming multipurpose—used as primary schools
Sustainable farming - USAID has provided 30,000 farmers with sustainable farming technique
NGOs – education and disaster preparation – reduces impacts of hazards
NGOs – latrines/toilets high above ground (so floodwater/ water supply isn’t contaminated).
Storage tanks for rainwater installed
