IMPLICATIONS OF GLOBAL ENVIRONMENTAL CHANGE FOR FLOOD-PRONE AREAS IN THE

EASTERN HIMALAYAN REGION

Ahsan Uddin Ahmed

Bangladesh Unnayan Parishad (BUP)

GECAFS-IGP-APN Project Launching Meeting, Kathmandu, 29-30 June 2006

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

The Eastern Himalayan [i.e., Ganges-Brahmaputra-Meghna (GBM)] River Systems in South Asia

GBM River Systems

Spreading over five countries: Bhutan, China, India, Nepal, and Bangladesh

The three basins cover an area of 1.75 Million square kilometers

The second largest outfall after the Amazon System

Perennial Rivers

Average annual flow: 1360 Billion cubic meters

Contributed to the development of the largest delta on earth

These river systems support agriculture-based livelihoods of about 650 Million people in South Asia

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

THE HK HIMALAYAS

GBM Rivers are strongly influenced by SW-Monsoon

Monsoon generates ‘too much water’

There is water scarcity during the dry winter season (‘too little water’)

High spatial and temporal variability in water availability throughout the GBM region cause problems

Floods

Ag. Droughts

Salinity Ingress along the coast

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Over 80% of rainfall occurs during June – September

The River Systems cannot drain

Riverbank overtopping and flood

Catastrophic floods

In India (Bihar, West Bengal, Assam)

In Nepal (Terai region)

In Bangladesh

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Concerns of GEC

Global Climate Change

Acid Rain

Asian Brown Cloud

Urbanization

Globalization

Other local factors

Population dynamics

Dynamics in geo-physical systems

Social and economic aspects

Climate change

Sea level rise

Precipitation

River water levels

Unprotected area: bank overflow

Sedimentation in floodplains

Protected area: risk of

flooding Bed levels

Maximum river flow

Runoff

Water logging

Impacts on flood

>> : Increase expected << : Reduction expected

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>> Backwater effect

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Too much water in monsoon

monsoon

Ahmed et al., 1998

Extent of Change:

There will be a general rise in surface average temperature: 1.3°C by 2030s; 2.6°C by 2070s.

Monsoon rainfall will increase by 7% by 2050s and 11% by 2080s.

Number of rainy days in the region will increase by about 20 days.

More catastrophic floods

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Courtesy: IITM

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Months

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Observed

CTL

GHG (2041-60)

Courtesy: IITM

Models such as HadCM project wetter monsoon over the South Asian Region. Wetter monsoon means higher amounts of water being available.

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Climate change

Sea level rise

Precipitation

River water levels

Unprotected area: bank overflow

Sedimentation in floodplains

Protected area: risk of

flooding Bed levels

Maximum river flow

Runoff

Water logging

Impacts on flood

>> : Increase expected << : Reduction expected

>>

>>

>>

>>

>> >>

>> >> >>

>>

>>

>> Backwater effect

>>

>>

Too much water in monsoon monsoon

Global Warming will also cause rise in sea level. Along the coastal rivers, where discharge requirement is even higher than the floodplains in general, a combination of se level rise and sea level will increase flood vulnerability.

Ahmed et al., 1998

Since mid-1970s, Bangladesh has enhanced its capacity to deal with moderate (once in a twenty-year flood) floods. Such a coping was made possible by building embankments. However, flood controlling structures are not so effective to offer protection against catastrophic floods.

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Choudhury et al., 2003

Level of inundation in Dhaka city

Trapped in floodwaters

?

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications for urban areas

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

IMPLICATIONS OF FLOODS: HUMAN DIMENSIONS

Immediate Effects

• Temporary Displacement

• Drowning and Snake-bites

• Loss of Income & Economic Opportunities

• Non-availability of Potable Water

• Suffering from Water-borne Diseases

• Lack of Cooking Energy

• Inability to Purchase Consumable Items

Problems Faced by Women and

Children

Price hike

Lack of Supply of Commodities

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

IMPLICATIONS OF FLOODS: HUMAN DIMENSIONS

Long Term Effects• Crop Failure and Food Security• Energy Security • Rehabilitation• Disruption of Services

EducationTransportationHealth CareEnvironmental ServicesSecurity

Problems Faced by Women and

Children

Price hike

Lack of Supply of Commodities

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting

THANK YOU

In the dry season, reduced river flows give rise to salinity ingress along the coastal rivers

Currently, over 15 million people in Bangladesh alone are forced to drink saline water

Implications of GEC for Flood-prone Areas in the Eastern Himalayan Region GECAFS-IGP-APN Project Launching Meeting