► Location and extent of Sunderban.► Sunderban in the 17th century.► Physiography of Sunderban.► Resource function of the Sunderban.► Historical phases of land reclamation.► Polderization of the landscape & topographic change.► Drainage character & their changing behaviour.► Hazards of the Sunderban …..

- River bank erosion.- Cyclone and tidal wave.- Floods and inundations.- Soil and water salinity.- Impact of sea level rise.

► Human impact in the Sunderban.► Sunderban biosphere reserve.► Prospects of eco-tourism in Sunderban.

The Sunderban is the world’s single largest mangrove forest that extends across Bangladesh and the Indian state of West Bengal on the coastal zone of Ganga delta.

-: FOREST AREAS :-

► Bangladesh : 6017 km2 (1874 km2 constitute the river water area)

► West Bengal, India : 4264 km2 (1100 km2

constitutes the river water area)

The Sundarban comprises an extensive tidal flat, low-lying coastal and deltaic land formed by the deposition of fluvio-marine sediments at the confluence of the three mighty rivers of the Ganges, Brahmaputra and Meghna. It is criss-crossed by large tidal rivers as well as channels and creeks, all discharging into the Bay of Bengal.

The most important physiographical feature around Sundarban was its wetland and water bodies. Inlands, the Sundarban was dominated by the tropical evergreen species Heriteria Fomes known in Bengali as Sundri. The coastal half of the region displayed salt to learnt mangrove forests.

Throughout the Sundarban several hundred other plant and animal species were linked in a dense productive wetlands ecosystem.

The human population was limited to a few fisherman, salt makers, smugglers and pirates living on the island of the coastal mangrove. Parties of woodcutters and hunters made regular forays into the interior forest by boats but rarely, if ever, made permanent home in the wetland.

The Sundarban, along with other lands lying outside the area of cultivation and settlement full under state ownership due to new rule of landed property imposed for Bengal under the terms of the “ Permanent Settlement” in 1793.

The Bengal government has appointed a civil officer as commissioners of Sundarban. This officer was charged with demarcating and managing the water logged forests and swamps of the lower delta in1816. However the commissioner was above all to ensure that private landowners cleared, settled and reclaimed the Sunderban swamps for rice cultivation.

A protracted survey operation completed in1830 demarcated boundaries and offered security to tenure to improve landowners in this difficult terrain. (Hunter,1875; Pargiter, 1934)

The Bengal Government slowly but steadily invested in canals, levees and embankment for water control. The river system offered a long-standing efficient transport network for the country boats and increasing numbers of steamers.

Finally modest investment in piloting aids and port facilities were deemed sufficient to meet the needs of growing river tariff between the delta and the larger cities.

Land reclamation and settlement in the Sunderban progressed each year as the wetlands proved to be generally fertile and productive. Therefore the ubiquitous depression had to be embanked, and channels dug and maintained to control the inflow of water from riverine flooding.

An intensive reconstruction of land use changes in Bengal for past centuries confirms this picture of wetland depletion. Within districts of 24-parganas(India), Bakarganj and Khalna(Bangladesh) which includes the Sundarban at its boundary, total wetland declined by 2750 km2 in the 60 years- between 1880 and 1940. Between 1940 and 1980 the pace of reclamation quickened by 5230 km2

as subsistance3 demand for population and crowding in the countryside pressure against every available scrap of land.

Land use type

1880 1900 1920 1940 1960 1980

Total usable and settled (km2)

14570 16140 15830 16710 20820 21860

Total Wetlands(km2)

15160 13960 13940 12410 8530 7180

Total Population (million)

5.5 6.8 8.0 11.5 15.9 25.1

Land use changes in Sundarban, 1880-1980

By 1947 some 10,000 km2

Sundarban lands full under government forest status. After independence, 60% went to the East Pakistan (Later Bangladesh) and the remaining 40% to India.

Following administrative blocks are mostly or partially affected by salinity,

Sundarban area reclaimed portion in North 24-pargana.

Hasnabad, Haroa, Minakhass, Sandeshkhali I and II, Hingalganj,

Gosaba, Bhangar I and II, Canning I and II, Basanti, Jaynagar I and II,

Kultali.

Sundarban area reclaimed portion in South 24-pargana.

Magrahat I and II, Diamond Harbour I and II, Mandirbajar, Kulpi,

Mathurapur I and II, Patharpratima, Kakdip, Nmakhana, Sagar

Major hazards and disasters of the Sunderban region :

1.Cyclone/storm surges.2. River bank erosion.3. Flood or inundation.4. Impact of sea level rise.5. Salinity of soil and water.

The whole Sunderban of active and abandoned parts of the Ganga delta is intersected by networks of rivers and water resources. The great trunk channels enter the Sunderban from the north and are connected by innumerable distributaries, which, after endless bifurcation and inter lacings, united into large estuaries falling into the Bay of Bengal.

The principal of these arms of the sea , proceeding from west to east, are-

01. The Hugli02. The Saptamukhi03. The Jamir04. The Matla05. The Bangaduni06. The Gosaba07. The Raimangal08. The Malancha09. The Barapanga10. The Marjata or kaga11. The Bangara12. The Haringhata or Baleswar13. The Rabnabad Channel14. The Meghna river

Sunderban is selected as biosphere reserve for the following reasons,

1. Among the mangrove forest of the world Royal Bengal tiger is only found in the Sundarban.

2. Sundarban mangroves occupy over 60% area of Indian mangrove forest.

3. Such diversity of mangrove trees are not found in any other mangrove belt of the world. About 64 mangrove species are found in the Sundarban.

4. Among the endangered species a few animals and plants are steel available in the Sundarban forest.

5. Sundarban mangrove act as buffer against the cyclonic storm and they stabilize the coastal belt from erosive forces of sea wave and tidal currents.

Sundarban rivers can be grouped on the basis of distribution of the various source of supply. Theses sources are,

a. Upland fresh waterb. Local drainage from the land

which concentrate in the bills c. Tidal water from the bay.

Group (a) includes the Bhagirarhi, Jalangi and Mathabhanga and sometimes the Moynacotta.Group (b) includes the Kulpatooa, Habra Gong, Seepsah, Bhudder and Rampal rivers.Group (c) includes the Saptamukhi, Thakusoan, Peali and Matla rivers.

The Hooghly, Pusur and Bagerhat river, Kaliganga, Swarupkati, Urialkhan and Barisal rivers are example of semi fresh water and tidal rivers.

Some of the Sundarban rivers obtain a supply of more silt than the others. Purely tidal rivers of this group are dying rapidly by the silt supply from the bay and other semi fresh water river. The flood tide picks the ndeposit of estuary mouth and carries it up the maion river, where it settles and remain as a fixed deposit owing to the weakness of the ebb current.

Diaqmond Harbour creek and the Bidyadhari are already deteriorated, and Saptamukhi, Thakuran and Matla rivers are rapidly being filled up with silts.

Storm waves of the previous centuries generated on the Bay of Bengal have pushed upward along the natural passage of Sundarban rivers and produced damages to the bank. Other disturbances are recorded as,

1. Rise of water level in the rivers.2. Shifting of depositional bars and shoals.3. Change of river courses.4. Inundation and flooding over the inland tracks.5. Embankment breaches etc.