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.

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

• 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

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

Precipitation intensity Dry days

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 -2-

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 -3-

 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 challengesShifts in spatial and temporal distribution of impactsSea level rise, changes to ocean salinity and aciditySea temperature rise causing fish to inhabit different ranges.

Decline in yields and productionReduced marginal GDP from agricultureFluctuations in world market pricesChanges in geographical distribution of trade regimesIncreased number of people at risk of hunger and food insecurityMigration 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:• 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 micro-organisms 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 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

Climate changescenarios

Biophysical impacts

Socioeconomic impacts

Autonomousadaptation Integration

Vulnerability

Purposeful adaptations

Baseline Scenarios• Population• GNP• Technology

• Institutions• Environment

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 GCMto 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.