Mangrove wetland ecosystems in Ganges-Brahmaputra delta in ...

444 Shafi Noor ISLAM, Albrecht GNAUCK
The data was processed and analyzed through MS Excel,
GISArcView 9.1 for data visualization and MATLAB
software version 7.1 were used for simulation.
6 Results and discussion
To understand the real situation in the Sundarbans
region, 13 important rivers (Fig. 5) located around
the case area have been chosen for modelling of their
water salinity. The time series data of water salinity has
been collected from 13 river basins (Fig. 5) in the
Sundarbans mangrove wetlands area based on the
potentiality of the river basins and ecosystems balance.
All 13 rivers show increasing water salinity. The results
of the investigation of water salinity show that the
salinity rate is much higher in the southern and
south-western rivers; the rivers of the middle area are
moderate level and the rivers of the northern portion
carries low salinity than the rivers of middle area of the
Sundarbans (Figs. 4 and 5).
The river water salinity trends show that only one river
has crossed the threshold line (43220 dS/m) (Colugh,
1985) in 2000; six rivers have crossed the threshold line
in 2001; eight rivers have crossed the threshold line in
2002; and eleven rivers have crossed the threshold line in
Fig. 4 The increasing salinity trends in the Sundarbans
2003 (Fig. 4). Therefore, the results show that the river
water salinity trends are gradually increasing and more
rivers are affected by NaCl in the Sundarbans in
Bangladesh.
The high salinity zone is located in the south-western
corner of the Sundarbans, where the previous salinity
values were 38 898 dS/m to 54025 dS/m, whereas the present
values are 54025 dS/m to 69152 dS/m. The high saline
affected area extends from south to north and east to
west direction, which is poses an extremely high threat for
mangrove wetland ecosystems in the Sundarbans. The
results of water salinity simulation of the Sundarbans
Rivers will support the formulation of a plan by decision
makers to protect the special natural heritage site and
mangrove wetlands ecosystems in the Sundarbans region
in Bangladesh (Fig. 4).
6.1 Water allocation in the Ganges basin
The Ganges River rises at an elevation of 7667 meters in
Gangotri glacier of Kashi district of India on the southern
slopes of the Himalayan range. The length of the
river in Bangladesh is about 2550 km and covers an area
of about 46300 km 2 . It stretches for more than 1600 km 2
between Tibet in China and India. The three major tributaries,
Gandok, Ghagra and Kosi pass through the