The probable impacts of climate change on poverty - UNDP

years in the coastal areas <strong>of</strong> Bangladesh is 5-6 mm a year. <strong>The</strong>refore, while sea level rises 7 mm/year and the land
rises 5-6 mm/year. From the above figures it may appear that the relative sea level rise in the coastal areas <strong>of</strong>
Bangladesh is 1-2 mm/year but significant implication <strong>of</strong> the sea level rise is losing the productive land which has
formed over time.
Salinity intrusion in surface water is highly seasonal in Bangladesh. Salinity and its seasonal variation are
dominant factor for coastal echo-system, fisheries and agriculture. <strong>The</strong>refore, any <strong>change</strong>s on present spatial and
temporal variation <strong>of</strong> salinity will affect the biophysical system <strong>of</strong> coastal area. Distribution <strong>of</strong> salinity level and
landward intrusion in the rivers and surface water for the base condition has been assessed using the southwest
region model and Bay <strong>of</strong> Bengal model for dry and monsoon season. For the base year 2005, it is found that in
monsoon (June to September), the saline water is fully flushed out <strong>of</strong> the Meghna Estuary, but in the western
part <strong>of</strong> the lower delta it is still saline due to scarcity <strong>of</strong> fresh water flow from upstream. It is found that 5 ppt
isohaline (line <strong>of</strong> equal salinity level) intrude more than 70 km landward in the western part <strong>of</strong> Sundarbans,
through the lean flowing Jamuna-Malancha-Raimangal river system, whereas comparatively higher freshwater
flow through Pussur-Sibsa river system pushes the 5 ppt saline front more downward and keeps it at the estuary
mouth. Similarly, the Baleswar-Bishkhali river systems with higher monsoonal freshwater flow from the Padma-
Lower Meghna, keeps this south central region almost saline free during monsoon. During dry season (December
to March) deep landward intrusion occurs through various inlets in the western part <strong>of</strong> coastal zone and through
Meghna Estuary.
Salinity will intrude more landward specially during dry season due to sea level rise. Consequently brackish water
area would increase and it is seen that sea level rise <strong>of</strong> 27 cm causes 6% increase <strong>of</strong> brackish water area
compared to base condition. About an additional area <strong>of</strong> 327,700 ha would become high saline water zone (>5
ppt) during dry season due to 60 cm sea level rise. In the monsoon about 6% <strong>of</strong> sweet water areas (276,700 ha)
will be lost. Impact <strong>of</strong> 15cm sea level rise on salinity intrusion under low emission scenario B1 in the year 2080 is
insignificant.
Table 5.5 Changes in fresh and brackish water area [Ha] in dry and monsoon
Scenario Dry Season Monsoon Se ason
Fresh water Brackish water Change Fresh water Brackish water Change
area (1 ppt) (%) area (1 ppt) (%)
Base 2,562,500 2,152,000 3779600 9403
A2, 27cm
[2050]
2273300 2441200 3665400 10508 114200
A2, 62cm
[2080]
2135700 2578800 426800 3502800 12111 276700
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<strong>The</strong> Probable Impacts <strong>of</strong> Climate Change on Poverty and Economic Growth and
the Options <strong>of</strong> Coping with adverse Effect <strong>of</strong> Climate Change in Bangladesh