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Managing water in a drier and more erratic MENA climate

RPCD Session – Arab Water WeekAmman, Jan 27, 2013

Hamed Assaf

January 27, 2013

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Key pointsClimate models project a warmer,

a drier and a more erratic MENA climate.

Deep uncertainties obscure these projections at the national and regional levels.

How to manage water resources under these deep uncertainties.

Key messagesJanuary 27, 2013

The wet will get wetter and the dry will get drier

January 27, 2013Source: NOAA Geophysical Fluid Dynamics Laboratory

Difference between the 2081-2100 average and the 1950-2000 average (A1B - GFDL CM2.1 model)

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January 27, 2013

Mecca 21.43°N

White Nile

20°N

Euphrates & Tigris40°N

Equator

Blue Nile

1950-2000 Precipitation

21st Precipitation Change

Inches of liquid water per year

30°N

10°N

Sanaa 15.35°N

Beirut 33.90°N

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Precipitation Change (15 GCMs for A1B1 Storyline)

(2080-2099) vs. (1980-1999)

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The North Atlantic Oscillation (NAO) January 27, 2013

The North Atlantic Oscillation (NAO)

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NAO+• Westerlies

shift to the north

• Wet winters in Europe, Canada and the USA.

• Dry winters in southern Europe, North Africa and Eastern Mediterranean.

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NAO-• Westerlies

shift south.

• Dry winter in Europe, Canada and the USA.

• Wet winter in southern Europe, North Africa and Eastern Mediterranean

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Climate change projections for the MENA Region

Northern Africa and the Eastern Mediterranean – including the headwaters of Tigris and Euphrates – will receive less precipitation.

The Nile headwaters – with less certainty in the Ethiopian highlands - are likely to receive more precipitation.

No or positive increase in precipitation is expected in the southern regions (e.g., Yemen, Oman & UAE).

Dry periods will increase in frequency and duration with significant impacts on rain-fed agriculture and grazing.

Extreme rainfall events will increase in severity and frequency.

Agricultural water demand will increase due to higher evaporation rates and longer growing seasons.

Snowpack will decline.

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Uncertainties in climate projectionsGCMs only project long-term trends at the

global level. They can not be used directly in short-term

forecasts at the national or regional levels.Downscaling – dynamic or statistical – is

applied to provide more reliable projections at the regional level.

Deep uncertainties still persist in the timing and distribution of climate change manifestations at the national and regional levels.

For example: there is a general agreement that the Eastern Mediterranean is going to undergo warming and drying, yet the amount and timing of precipitation reduction in a specific basin within Jordan or Lebanon can not be determined based on climate projections.

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Deep uncertainty?Deep uncertainty refers to the presence of one or more of the following elements with interrelated and/or unknown probabilities (Hallegate et al. 2012):

◦Multiple possible future worlds;◦Different views and values of these worlds; and

◦Different and highly interrelated responses.

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Sources of deep uncertainties in climate projections

GHG emissions uncertainties: dictated by socio-economic developments, technologies and policies.

Modeling uncertainties: result from limitations in the scientific understanding and modeling of the climate system.

Natural variability: relates to the chaotic nature of the climate system.

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In a region known of its data scarcity, it is quite challenging to reliably assess hydro-climatic variability.

January 27, 2013Source: World Bank (2007). Making the Most of Scarcity

Frequency decreases as more years preceding the base year are included. Overall frequency increased over the past few decades.

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Unrepresentative hydrologic analysis can be costly.

January 27, 2013Source: World Bank (2007). Making the Most of Scarcity

Dams were designed based on a wetter period. They did not fill for two decades and could not deliver planned irrigation allocations.

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Managing water under the deep uncertainty of climate change

Stationarity is false. The future can not be solely based on past patterns, especially if available record is short.

Knowledge of climatic changes improves as time progresses. Consequently solutions should be flexible enough to accommodate future changes.

Focus on robust rather than optimal solutions. Optimal solutions are only optimal if assumptions about future conditions are realized.

Robust solutions are flexible solutions that can be adapted – and are consequently less vulnerable - to changing conditions.

Involve the stakeholders and the public in managing water resources.

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Recent trends in decision making and planningThe rising prominence of climate change as a

development challenge has caused a shift in decision making and planning (from optimal to robust decision making)

Optimal approach: determine optimal solution based on most likely outcome or a set of outcomes each characterized by its probability of occurrence.

Robust approach: given the presence of deep uncertainty, identify plausible outcomes and most significant ones, and assess vulnerabilities and performances of solutions based on stakeholder-centered process. Reiterate as more information becomes available.

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Case Study: The Colorado River Basin Water Supply and Demand Study (Dec. 2012)

The Colorado River Basin stretches over 7 states and provides water supply to over 40 million people in addition to irrigation, hydroelectric generation, flood control and ecosystem services.

The study was commissioned by the US Bureau of Reclamation to explore options to address imbalances between water supply and water demand under changing climatic and socio-economic conditions.

The study employs a scenario-based simulation approach guided by input from stakeholders and the public to address high uncertainties in future water supply and demand.

January 27, 2013

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Case Study: The Colorado River Basin Water Supply and Demand Study (Dec. 2012)

Interventions were expressed as portfolios each composed of several options.

The portfolios were assessed in terms of cost, performance in meeting resource requirements and effectiveness in reducing system vulnerabilities.

The study did not recommended a specific course of action. It characterized portfolios as exploratory strategies to guide the process of addressing the system’s vulnerabilities emanating from imbalances between water supply and water demand.

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The Colorado River Basin Study Approach

January 27, 2013 Source: US Bureau of Reclamation (2012). “Colorado River Basin Water Supply and Demand Study

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Development of water supply and water demand scenarios

January 27, 2013 Source: US Bureau of Reclamation (2012). “Colorado River Basin Water Supply and Demand Study

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Development of options and strategies

Input was solicited from study participants, stakeholders and the public.

Options were categorized into: increase of water supply; reduce water demand, modify operations, and governance.

Options were characterized according to several criteria including: timing, cost, and technical feasibility.

Submitted options (150) were reformulated into representative options (30).

Alternative portfolios (sets of options) were formed to address imbalance between supply and demand.

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Formulation of portfolios

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C: Favors environmental protection and low energy consumption(GW desalination, reuse, & watershed management)

B: Low-risk strategy, proven technology & reliability (desalination, water reuse & conservation)

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Performance in reducing system’s vulnerabilities

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Cost

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World Bank’s Flagship Report “Adaptation to a changing climate in the Arab countries”Developed through a consultative process

involving Arab governments, stakeholders & experts.

Launched recently in Doha’s climate change conference.

Provides assessment of the impact of climate change on the Arab region and offers advice on adaptation strategies and options in key areas (health, water, agriculture, urban development and tourism).

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Key messages and policy options - Water

Climate change will aggravate the water supply and demand gap.

Integrate water resources management across water and nonwater sectors (agriculture, tourism & urban development).

Upgrade disaster risk management for floods and droughts.

Water demand-side management is important given the limited scope of securing newer water supplies.

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Key messages and policy options - Water

Improve water-use efficiency in agriculture.

Develop laws and guidelines supported by effective enforcements to protect water resources from pollution.

Enhance regional economic integration to facilitate water investment and virtual water trade.

Invest in research & development.Improve water governance

January 27, 2013