The Sundarbans Flashcards
Location of the Sundarbans
Extends over southern Bangladesh and India on the Bay of Bengal
Size of the Sundarbans
around 10,000 km^2
Two natural features of the Sundarbans
World’s largest delta
Extensive mangrove forest
Which 3 other rivers flow into the delta
Ganges
Meghna
Brahmaputra
Natural processes invovled in the creation of this landscape
Deposition
Tidal processes
Marine erosion
Aeolian/wind transport and deposition
Role of deposition
The three rivers carry large amounts of fine sediment
The sediment builds up in mounds or islands - creating a netword of interconnected channels flowing round the isalnds called khals
silt and clay is quit cohesive so is resistant to erosion
Role of tidal processes
Twice a day at high tide water washes northwards into the delta and then at low tide water washes southwards
This regular tidal flow has created large straight channels running north to south
This channels are alos connected to each other by khals
Role of aeolin/wind processes
Less cohesive sand is carried further towards the mouths of the channels nearer the coastline
Some of the sand builds up to create chars
When the sand is dry and above the waterline it can be transported more inland and form sand dunes
Role of vegetation succession
Sediment build up the island will remain above the water under normal conditions
Vegetation success will take place with salt tolreant pioneer species and progress to the climax vegetation of mangrove trees
Root systems of the mangrove trees will stablise the islands prevent more erosion and trap more sediment
Vegetation succession will also occur on the sand dunes providing further protection
Goods provided by the mangrove forest
Wood - provide fuel for heat and cooking, , for furniture and construction
Natural poison and floats - help in catching fish which is an important food source
Rich ecosystems providing many food items - crab , shrimp , honey , leaves and fruit
Commercial products - textiles , fur and skins , natural dyes , wax , glue , medicines and paper
Servies that the mangroves provide
Protection from flooding and cyclones
Important carbon sink - around 4 billion tonnes of CO2 a year
Provides nursery grounds for fish which helps maintain the natural ecosystems
Ecotourism
Education
Scientific research
Cultural , spiritural and religious value
Risk of living in the Sundarbans
Royal Bengal tigers - increase risk of decreasing habitat and increased population growth
Coastal flooding - eustatic change - increasing levels of salinity in the soil making agriculture difficult and affeecting freshwater supplies
More intense cyclones - increase risk of erosion , flooding and damage to forest , increasing risk to people and property
Coastal resources are being over exploited - due to population growth and more destructive fishing techniques
Way people are adapting
Salt tolerant varieties of rice
NGOs building latrines on higher ground to avoid contamination of the water supply
USAID trained 30,000 people in the use of improved agriculutral techniques more suited to the conditions caused by climate change
Storage tanks for rainwater used to protect supplies in areas of high risk of saltwater intundation
Cyclone shelters are becoming multi purpose - used as primary schools
Examples of resilience
Mangrove forest allows people to be resilient in the face of a storm - density of 30 per 0.01 hectares of trees can reduce the destructive force of a cyclone by up to 90%
Mangrove also provide a wealth of goods and services - natural fertility of soil
When only used for traditional activites the forest has an economic value of $12,000 per hectare
Examples of mitigation
Community access to natural resources on khas land as well as access to the forest and fishing
Significant investment in infrastructure - cyclone shelters , flood protection and tube wells
NGOs and government provided micro-credit for business to proivde a economic safety net
Afforestation of mangrove forest on some islands
