Transcript IWRM as a Tool for Adaptation to Climate Change IMPACT

IWRM as a Tool for Adaptation
to Climate Change
Impacts on Water Use
Sectors and Impact Assessment
Techniques
OUTLINE
Impacts of climate change on water resources
Projected climate changes by region
Impacts climate change on selected sectors
Approaches of Climate Change Impact, Adaptation and
Vulnerability (CCIAV) Assessment
 Climate change scenarios
 Water resources and climate change
 Modelling of water resources systems.
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Projected change in hydro
meteorological variables
 Based on 15 Global
Circulation Models (GCMs)
 SRES A1B scenario
 Four variables:
― precipitation
― evaporation
― soil moisture
― runoff
 Annual mean changes for
2080–2099 relative to
1980–1999
 Regions where models
agree on the sign of
change are stippled.
Inferences
 Heightened water scarcities in several
semi-arid and arid regions including
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Mediterranean Basin
Western USA
Southern Africa
North-eastern Brazil.
 Precipitation is expected to increase at
high latitudes (e.g. northern Europe) and in
some subtropical regions.
Projected change spatial patterns of
precipitation intensity and dry days
Precipitation intensity
Dry days
 Based on 9 GCMs
 SRES A1B scenario
 Changes in spatial pattern of
―precipitation intensity
―dry days
 Annual mean changes for 2080–2099 relative to 1980–1999
 Stippling: at least 5 out of 9 models concur denoting that
change is significant
Projected changes by region
Africa:
• Water scarcity conditions in northern and southern Africa
• More precipitation in Eastern and western Africa
• Nile Delta expected to be impacted by rising sea levels.
Asia:
• Reduce precipitation in the headwaters of the Euphrates and
Tigris
• Winter precipitation to decrease over the Indian
subcontinent, and monsoon rain events to intensify
• Maximum and minimum monthly flows of Mekong expected
to increase and decrease, respectively
• Decline of glaciers is expected to continue reducing water
supplies to large populations.
Projected changes by region
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Australia and New Zealand:
• Runoff in the Darling Basin expected to decline
• Drought frequency to increase in the eastern Australia
Europe:
• Mean annual precipitation to increase in Northern
Europe and decrease further south
• Mediterranean and some parts of central and Eastern
Europe to be more prone to droughts
• Flood risk expected to increase in Eastern and Northern
Europe and the Atlantic coast.
Projected changes by region
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Latin America:
• Number of wet days expected to increase over parts of
south-eastern South America and central Amazonia
• Extreme dry seasons to become more frequent in
Central America
• Glaciers are expected to continue the observed
declining trend.
North America:
• Climate change to constrain already over-allocated
water resources, especially in the semi-arid western USA
• Water levels to drop in the Great Lakes
• Shrinkage of glaciers to continue.
Major water resources systems and sectors
to be impacted by climate change
 Systems and sectors connected to human
development and environment:
•Urban infrastructure: water supply and sanitation,
urban drainage and solids
•Water related natural disasters: floods, droughts,
landslide and avalanche
•Rural development: agriculture, food security,
livelihoods and environment
•Energy: demand and production (hydropower)
•Transportation: navigation
•Health: Human and animals
•Environment: system sustainability in wetlands,
water quality, forest burn, etc.
Impacts of CC on food production
Biophysical
Socio-economic
Physiological effects on crops,
pasture, forests, livestock (quantity,
quality)
Changes in land, soil, water
resources (quantity, quality)
Increased weed and pest
challenges
Shifts in spatial and temporal
distribution of impacts
Sea level rise, changes to ocean
salinity and acidity
Sea temperature rise causing fish to
inhabit different ranges.
Decline in yields and production
Reduced marginal GDP from
agriculture
Fluctuations in world market
prices
Changes in geographical
distribution of trade regimes
Increased number of people at
risk of hunger and food
insecurity
Migration and civil unrest.
Agriculture
 Possible positive impacts because of increased CO2
concentrations and length of growing season
 Strongly dependent on water (amount and timing):
• Rain-fed agriculture: precipitation
• Irrigated agriculture: water supply
 Examples:
• Warly snowmelt > water shortage in summer
• Insufficient treated wastewater used for irrigation > water-born
diseases
• Too much precipitation: direct damage to crops, soil erosion
• Too little precipitation: direct damage to crops
 Strong regional and local differences: those least able
to cope (smallholder farmers in marginal areas) will be
affected hardest.
Fisheries
 Increased stress on fish populations:
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Higher temperatures > less oxygen available
Increased oxygen demand
Deteriorated water quality
Reduced flows
 Other human impacts probably greater:
• Overfishing
• Flood mitigation
• Water abstractions
 Lake Tanganyika: reduced primary productivity due to
decreased depth of thermocline.
Impacts of CC on water supply
 Further reduction of water for drinking and hygiene
 Lowering efficiency of sewerage systems > more microorganisms in raw water supply
 Increased concentration of pollutants (less dilution)
 More overflows in sewerage systems with increased
precipitation > spread of waterborne diseases
 Increased salinity water resources.
Impacts of CC on health
Mediating process
Health outcome
Direct effects
Change in the frequency or intensity of
extreme weather events (e.g. storms,
hurricanes, cyclones)
Deaths, injuries, psychological
disorders; damage to public health
infrastructure
Indirect effects
Changed local ecology of water borne
and food borne infective agents
Changed incidence of diarrhoeal and
other infectious diseases
Changed food productivity through
changes in climate and associated
pests and diseases
Malnutrition and hunger
Sea level rise with population
displacement and damage to
infrastructure
Increased risk of infectious diseases
and psychological disorders
Social, economic and demographic
dislocation through effects on
economy, infrastructure and resource
supply.
Wide range of public health
consequences: mental health and
nutritional impairment, infectious
diseases, civil strife.
Impacts of CC on energy sector
 Temperature increase leading to increased energy
demand and less availability of cooling water
 Energy system highly dependent on hydropower, i.e. on
water availability
 Periods of low flow can create conflicts with other
users.
Impacts of CC on transportation
 Water links with transportation
• Use of drainage systems for navigation
• Drainage interface with the design of transportation
infrastructure networks
 Implications of climate change
• Reduction in the flow quantity or its distribution over
the year shall result in reduced river levels
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Big boats cannot be used thus more boats are required for the
same loads, increasing cost, energy use and emissions
• Increase in the rainfall intensity can severely damage
the transportation infrastructure due to exposure to
higher flooding than the infrastructure is designed for.
IWRM as a Tool for Adaptation
to Climate Change
IMPACT ASSESSMENT TECHNIQUES
CCIAV assessment approaches (Frameworks)
 Impact assessment
 Adaptation assessment
 Vulnerability assessment
 Integrated assessment
 Risk management.
CCIAV: Climate Change Impact, Adaptation and Vulnerability
Characteristics of CCIAV assessment approaches*
Source: Climate Change 2007: Impacts, Adaptation and Vulnerability.
General Impact Assessment Approach
Baseline Scenarios
• Population
• Institutions
• GNP
• Environment
• Technology
Climate change
scenarios
Biophysical impacts
Socioeconomic impacts
Autonomous
adaptation
Integration
Vulnerability
Purposeful adaptations
The 7-step assessment framework of IPCC
1. Define problem
2. Select method
3. Test method/sensitivity
4. Select scenarios
5. Assess biophysical/socio-economic impacts
6. Assess autonomous adjustments
7. Evaluate adaptation strategies.
Three types of climate change scenarios
• Scenarios based on outputs from GCMs
• Synthetic scenarios
• Analogue scenarios.
General Circulation Models (GCMs)
 Computer applications designed to simulate the Earth’s
climate system for the purpose of projecting potential
climate scenarios
 Range in complexity from simple energy balance models to
3D General Circulation Models (GCM)
 The state-of-the-art in climate modeling is represented by
the Atmosphere-Ocean GCM (AOGCM).
Types of GCM runs
 Equilibrium:
• Both current and future climates are assumed to be in state
of equilibrium
• Simulations are executed assuming doubling or quadrupling
of GHGs concentrations
• Low computation cost, yet unrealistic.
 Transient:
• Future climate is simulated assuming a steady increase in
CO2
• Costly to run and needs a warming period to avoid
underestimating the earlier stage after present.
Advantages/disadvantages of using GCM
to generate climate scenarios
 Advantages:
• Produces globally consistent estimates of larger number
of key climate variables (e.g. temperature, precipitation,
pressure, wind, humidity, solar radiation) for projected
changes in GHGs based on scientifically credible
approach
 Disadvantages:
• Simulations of current regional climate often inaccurate
• Geographic and temporal scale not fine enough for many
impact assessments
• May not represent the full range of potential climate
changes in a region.
Dynamic downscaling
Dynamic
downscaling is
done by nesting
a fine-scale
climate model in
a coarse-scale
model
Synthetic scenarios
 Based on combined incremental changes in meteorological
variables such as (temperature, precipitation)
 Can be based on synthetic records created from combining
baseline data with temperature changes, e.g. +2oC, and
precipitation changes, e.g. 10%
 Changes in meteorological variables are assumed to be
annually uniform; few studies introduced temporal and
spatial variability into synthetic scenarios.
Advantages/disadvantages of synthetic
scenarios
 Advantages:
• Inexpensive, easy to apply and comprehensible by policy makers
and stakeholders
• Represent wide spectrum of potential climate changes
• Identify sensitivity of given sectors to changes in specific
meteorological variables.
 Disadvantages
• Assumption of uniform change of meteorological variables over
large areas may produce scenarios that are not physically possible.
• May not be consistent with estimates of changes in average global
climate
• Synthetic meteorological variables may not be internally
consistent with each other, e.g. increased precipitation is
expected to be associated with increased clouds and humidity.
Analogue scenarios
 Temporal analogue scenarios based on using past warm climates
as scenarios of future climate
 Spatial analogue scenarios based on using contemporary
climates in other locations as scenarios of future climate in
study areas
IPCC has made recommendation against using the analogue
scenarios since temporal analogues of global warming were not
caused by anthropogenic emissions of greenhouse gases and that
no valid basis exists that spatial analogues are likely to be
similar to those in the future.
Water resources and climate change
 Assessment of impact of climate change on water resources
and identification of adaptation strategies requires
consideration of both its biophysical and socioeconomic
aspects.
 Integrated water resources management (IWRM) provides an
ideal platform to carry out these tasks.
Water resources system incorporates
natural and human-made components
Source: UNFCCC Handbook on Vulnerability and Adaptation Assessment.
Modeling of water resources systems
 Two general types: optimization and simulation models
 Simulation models are suitable for scenario-based climate
impact assessment studies.