Download Impact of Himalayan Glacier Melting and Coastal Region

Impact of Himalayan Glacier
Melting and Coastal Region of
Bangladesh
Dr. Syed Hafizur Rahman
Associate professor
Department of Environmental Sciences
Jahangirnagar University
Dhaka, Bangladesh
E-mail: [email protected]
16 November 2011
Presentation Outline
• Himalayan Glaciers
• Impact of Climate Change (CC) in Himalaya
• Bangladesh Profile and Coastal Region
• Impact of CC in coastal region of Bangladesh
• Impact of HGM in coastal region of Bangladesh
• Way Forward
Bangladesh
The main Himalayan range runs west to east, from the Indus river
valley to the Brahmaputra river valley, forming an arc of 2,400 km
(1,500 mi) long, which varies in width from 400 km (250 mi) in the
western Kashmir-Xinjiang region to 150 km (93 mi) in the eastern
Tibet-Arunachal Pradesh region
HIMALAYAN: THE ROOF OF THE WORLD
• The Himalayas have the largest concentration of
glaciers outside the polar region.
•
Approximately 15,000 glaciers (covering an area of
33,340 sq.km), and 9000 glacial lakes throughout
Bhutan, Nepal and Pakistan, as well as selected river
basins in China and India (ICIMOD, 2007) which store
about 12,000 km3 of freshwater.
Impact of Climate Change (CC) in Himalaya
• “Himalayan glaciers are retreating more rapidly than
anywhere else in the world which is up to 70 meters
(230 feet) per year” (Mats Eriksson).
• resulting in an increase in the number and size of
glacial lakes and a simultaneous increase in the threat of
glacial lake outburst floods (GLOFs).
• “Temperature on the Tibetan Plateau is increasing by
0.3 degrees Celsius each decade that’s double the
worldwide average” (Xu Jianchu)
Impact of Climate Change (CC) in Himalaya
• “If the present rate continues, the likelihood of them
disappearing by the year 2035 and perhaps sooner is
very high if the Earth keeps warming at the current rate”
(ABC news).
• With the increased glacial melt, the trapped CO2 will
be released into the atmosphere causing further
environmental damage.
• The change in glacier ice or snowmelt impacts water
storage and the water yield to downstream areas.
Impact of Climate Change (CC) in Himalaya
Glacier retreat in the Pho Chu sub-basin of Bhutan: The Luggye Glacier retreated by
160m per year from 1988 to 1993, resulting in a high growth rate of Lake Luggye Tso.
(ICIMOD, 2007)
Impact of Climate Change (CC) in Himalaya
Glacier retreat in the Pho Chu sub-basin of Bhutan: The Raphsthreng Glacier retreated
on average 35m per year from 1984 to 1998, but from 1988 to 1993 the retreat rate
was 60m per year.
(ICIMOD, 2007)
Bangladesh Profile and Coastal Region
Bangladesh is one of the
largest deltas in the world,
formed by a dense
network of the
distributaries of the rivers
Ganges, Brahmaputra, and
the Meghna, and more
than 230 major rivers and
their tributaries and
distributaries.
The total land area is 147,
570 sq km and consists
mostly of low, flat land.
Trans-boundary rivers
Bangladesh Profile and Coastal Region
• Bangladesh has a
population of 142.319
million people with an
average population density
of 964 inhabitants per
square kilometer (2011)
• Bangladesh is
predominantly agricultural,
with two thirds of the
population engaged in
farming activities
Trans-boundary rivers
Map of the combined drainage basins of the Brahmaputra, Ganges, and Meghna
Bangladesh Profile and Coastal Region
• In terms of climate,
Bangladesh is characterized by high temperatures, heavy
rainfall, high humidity, and fairly marked seasonal variations.
Although over half of Bangladesh is north of the Tropics, the
climate is characterized as tropical for most of the year
because of the effect of the Himalayan mountain chain, with a
warm, almost uniformly humid climate throughout most of
the year. There are three main seasons in Bangladesh:
i. A hot summer season,
ii. A hot and humid monsoon season,
iii. A cooler and drier winter.
(Huq and Ayers, 2008)
Coastal Region of Bangladesh
The physical geography of Bangladesh is varied and has an area
characterized by two distinctive features: a broad deltaic plain
subject to frequent flooding, and a small hilly region crossed by
swiftly flowing rivers
The country is sloping gently from the north to the south,
meeting the Bay of Bengal at the southern end
According to the coastal zone policy (CZP, 2005) of the
Government of Bangladesh, 19 districts out of 64 are in the
coastal zone covering a total of 147 sub districts (upazillas) of
the country
On the south is a highly irregular deltaic coastline
of about 580 kilometers, fissured by many rivers
and streams flowing into the Bay of Bengal
… this is the part of the country most threatened
from any changes in climate system and in turn
any of the changes in the water balances of the
river due to the melting of the Himalayan glaciers
About 1,106 km3 of water crosses the borders of
Bangladesh annually:
Total Rivers: 808
Transboundary Rivers: 58
COASTAL ZONES
The coastal zone covers
47,201 square kilometer
land area, which is 32
percent of total landmass
of the country (Islam,
2004)
Water area covers 370.4
km (200 nautical miles)
from the coastline
(UNCLOS, 1982; Article
57), estuaries and the
internal river water
This zone is divided into three parts:
Eastern coastal zone
Central coastal zone
Western coastal zone
Impact of CC in coastal region of Bangladesh
• Coastal areas in Bangladesh are on the ‘front line’ of
climate change, directly affected by storm surges, drainage
congestion, and sea level rise.
• Most of Bangladesh is less than ten meters above sea
level, with almost ten per cent of the country below 1 meter,
making it extremely vulnerable to increasing high tides.
• With sea levels expected to rise by an average of two to
three mm per year during the first part of this century, the
effects on the coastal areas will be severe, and include
erosion, coastal land subsistence, siltation of river estuaries,
reduced sedimentation, water logging, and saltwater
intrusion.
Sea Level Rise
World Bank (2000) has estimated that by the year 2030 and 2050 at
least 30 and 50 cm sea level will rise respectively
0 cm SLR
32 cm SLR
88 cm SLR
Impact of CC in coastal region of Bangladesh
• The coastal area of Bangladesh and the Bay of Bengal are
located at the tip of the northern Indian Ocean, which is
frequently hit by severe cyclonic storms, generating long
tidal waves that are aggravated by the shallow bay.
• Although Bangladesh now has good early warning
systems and cyclone shelters have been constructed along
much of the coast, infrastructure and livelihoods are still
threatened and severely affected, hampering further
development of the coastal areas.
• 30 districts were damaged by cyclone Sidr for example,
with the 11 districts closest to the coast damaged most
severely.
Cyclone and Storm Surge
IPCC (2007)
concludes that a 510% increase in
intensity (windspeed) would
contribute to
enhanced storm
surges and coastal
flooding
Impact of HGM in coastal region of Bangladesh
• If climate change does alter the rainfall pattern in the
Himalayas, the impacts could be felt in the downstream
countries-that is, India and Bangladesh.
• By and large, dry-season flow in the major Himalayan
rivers in a given year results from the monsoon rainfall
of the previous year.
• Catchments in Nepal supply about 70% of the dryseason flow of the Ganges River, and tributaries of the
Brahmaputra River originating in Bhutan supply about
15% of the total annual flow of that river.
Impact of HGM in coastal region of Bangladesh
• If climate change disrupts these resources and alters
mountain hydrological regimes, the effects will be felt
not only in the mountain core of Tropical Asia but also
downstream, in countries that depend on this water
resource.
• The extent of flooding is exacerbated by the
sediment loads brought by the three major Himalayan
rivers, coupled with a negligible flow gradient, which
increases congestion.
Way Forward
• Although uncertainties about the rate and magnitude
of climate change and potential impacts prevail, but
there is no question that climate change is gradually and
powerfully changing the ecological and socioeconomic
landscape, particularly in relation to water
• Implementation of international and national
initiatives and policy to build community resilience
• In transboundary water sharing issues, Joint
watershed management concept would be a sustainable
approach to reduce climate change vulnerabilities and
its impacts on common water resources
Thank you
for Patience Hearing