Lesson 15-Contrasting coastal landscape beyond the UK- The Sunderbans Case Study Flashcards
Facts about Bangladesh
- 80% of country is low-lying
- 30% live in coastal zones (Bay of Bengal)
- 140, mil populatuion
- Monsoon climate, face storm surges
- Here at the coast features the confluence of 3 main rivers
- Snow melts from Himilayas
- Located East Asia, South of Himilayas and in the coastal zone, bay of bengal
- Number of people affected by flooding decreased by 35 million between 1988 and 2017
Facts about sunderbans
- 20% in India and 80% in Bangladesh
- High biodiversity-decreasing fish populations
- Precense of mangroves-1 million rely on them for rice or water
- Delta that carries sediment to sea
- 15,000 fishermen
- 6th largest shrimp farm in the world
- Environment is degredating due to salty water
What are mangroves?
- Trees that grow in slaine conditions
- Great at absorbing energy from storms
- 30 trees per 0.01 hectare and with a 100m can reduce the destructive force of a storm surge by 90%
- Roots trap sediment which develops mangroves
- Tigers, dolphins, deers, crocodiles
What processes occur in the sunderbans?
- Tide action
- River Processes
- Storms/wave action
Processes occuring here-Tide Action
- The main process is tides meeting a river current forming delta.
- Network of interconnecting rivers that deposit clay and silt as the tidal flow counteracts the river flow. Allow mud flats to develop.
- Extra high tides can cause salinisation of fresh water (more likely with climate change).
Processes occuring here-River provcesses
- Rivers bring sediment, fresh water and erosion
- River flow meets tide flow = deposition
- The Ganges river travels long distances across Bangladesh from the Himalayas this means often has a very large discharges bringing lots of freshwater to the area snowmelt in the Himalayas feeds these rivers.
- This can cause erosion at some times of the year.
Processes occuring here-Storms/ Wave action
- During monsoon season large destructive waves erode the islands and wash away the sediment deposits this can erode the Mangroves.
- Waves shape the deposited sediment to form new islands this allows vegetation to establish itself and allow succession to occur eventually forming the mangrove forests which are home to the Bengal tiger.
Opportunities in the sunderbans?
- Mangroves
- Biodiversity
- Shrimp farming
Opportunities-Mangroves
- Decrease the intensity of storms e.g. a mangrove section of 30 trees per 0.01 hectare and with a width of 100 m can reduce the destructive force of a storm surge by up to 90%
- Habitat for Bengal tigers, saltwater crocodiles, fishing cats, and various dolphin species
- Globally, 4.3% of mangroves are in the Sundarbans
- Deforested 1 hectare provides $12000 of economic development
- 57000 wood industry production units with 210,000 employees.
Opportunities-Biodiversity
- 260 bird species, the Bengal tiger and other threatened species such as the estuarine crocodile and the Indian python.
- The area is a UNESCO world heritage site due to importance
Opportunities- Shrimp Farming
- Large areas used and shrimp sold to M and S
- Bangladesh exported 30,000 tonnes of shrimp worth nearly $350m (£290m)
- More than 275,000 hectares of previous farmland have been flooded, mostly in the south-west, for intensive aquaculture.
What causes flooding in the sunderbans?
-Monsoon climate- this brings very heavy rainfall and snow. Soils are leached and heavy rainfall reaches rivers quickly through surface run off
-Spring snow melt –this results a rapid increase in river discharge.
-Deforestation – in areas near the source of the rivers due to increasing population in Nepal, trees are cleared for fuel and for grazing causing less evapotranspiration, more runoff and faster soil erosion.
-80% of Bangladesh is on a floodplain and a delta which is only 1m above sea level.
-The Ganges river has been diverted which causes flooding down stream.
-Tropical storms frequently hit Bangladesh.
What are all the challanges in the sunderbans?
-Overfarming
-Tiger attacks-22.7 people killed every year by tigers
-Diversion of the Ganges River
-Coastal flooding
-Large population
-Monsoon climate
-Snow melt from Himilayas- soil erosion and a rapid increase in river discharge.
-Deforestation
-Tropical storms
Challenges- Overfarming
-Saline water from shrimp has ruined farmland
-50% drinking water supplies have been contaminated with saline water
-17,000 ha of mangrove destroyed and used for agriculture in last 30 years
-50% male population moving away to India for jobs in construction