Responding to Challenges in Responding to Challenges in Assuring Resilient Water Assuring Resilient Water

Systems for TennesseeSystems for Tennessee

Tom WilbanksTom Wilbanks

Oak Ridge National LaboratoryOak Ridge National Laboratory

22d Tennessee Water Resources 22d Tennessee Water Resources SymposiumSymposium

Montgomery Bell State Park, TNMontgomery Bell State Park, TN

April 11, 2012April 11, 2012

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During Our Lifetimes, Water Has Changed from During Our Lifetimes, Water Has Changed from Being Something That We Could Largely Take for Being Something That We Could Largely Take for Granted to Being Something That Is Often Granted to Being Something That Is Often Surrounded by Risks and Uncertainties:Surrounded by Risks and Uncertainties:

• What does “resilience” mean for water systems?

• What are the main challenges that we face in Tennessee?

• What are the implications if we fail to meet these challenges?

• What kinds of responses make sense now to reduce current and future risks?

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What Does Resilience Mean for Water What Does Resilience Mean for Water Systems?Systems?

• Resilience means:

– Identifying vulnerabilities to multiple threats

– Taking action to reduce vulnerabilities (adaptation)

– Being prepared to respond in the event of a disruption

– Being prepared to recover from the disruption so that the systems are better than they were before

• Requires planning ahead and taking action at multiple scales

• Rooted in social dynamics of participative problem-solving

• Provides near-term benefits as well as longer-term risk reduction

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What Are the Main Challenges that We Face in What Are the Main Challenges that We Face in Tennessee?Tennessee?

• A very high likelihood of growing demands for water, associated with water requirements for economic and population growth in Tennessee

• A very high likelihood that conditions affecting water supplies will be changing in Tennessee, e.g., from climate change, with increasing risks of both seasonal droughts and episodic floods

• Uncertain availability in Tennessee of major public sector investments in order to improve water resource infrastructures

(…recent information from the current NCA process…)

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On the Demand Side, for Example:On the Demand Side, for Example:

• Population and economic growth, increased competition for water supplies (e.g., movement of the Sun Belt northward?)

Projected housing density for the conterminous US shown as (A) actual housing density in 2000; (B) modeled housing density in 2100 for base case; (C) for scenario A2, and (D) for scenario B1.

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On the Supply Side, Tennessee Will:On the Supply Side, Tennessee Will:

• Get warmer, with more and longer summer heat waves; increasing water consumption, evaporation/transpiration rates, and water temperatures

• Get drier in summers – seasonal pressures on reservoirs, leading to deeper and longer-lasting drawdowns

• See more of its precipitation falling in a smaller number of more extreme precipitation events – both more seasonal droughts and more flooding

• Be affected by more severe storm activity: tornadoes, rainfall from Gulf Coast hurricanes

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Annual and seasonal difference in temperature (°F) between 2041 and 2070 and between 1971 and 2000 derived from eight regional climate model simulations from the North American Regional Climate Change Assessment Program (NARCCAP).

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Mean change in annual number of days with a maximum temperature exceeding 95°F between 2041-2070 and 1971-2000.

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100150200250300350400450500550600

2010 2020 2030 2040 2050 2060W

ater

Yie

ld (m

m)

Predicted Southeast-wide 10-yr moving-mean annual water yield. The green area represents the range in predicted water yield over the four climate projections.

Mean trends predicted for 2010-2060 in mean annual water yield, normalized by 2001-2010 mean annual water yield. Hatched area represents locations where the predicted trend in water yield is statistically significant (p < 0.05).

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Mean change in annual number of days with precipitation exceeding 1 inch between 2041-2070 and 1971-2000

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Projections of the mean changes in the extreme Palmer Drought Severity Index (PDSI) for the 30-year period centered on 2050. (Figure is from Averyt et al. 2011 redrawn from Strezepek et al 2010). Approximate boundary of 100th meridian represented by blue line.

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Quantified risk to state GDP ($B) from 2010 to 2050 due to uncertainty in precipitation predictions. From Backus et al. (2010).

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The Water-Energy Nexus as an Example of The Water-Energy Nexus as an Example of Implications for Tennessee if our Water Systems Are Implications for Tennessee if our Water Systems Are Not Resilient:Not Resilient:

• Water availability and water temperature are salient issues for energy production in Tennessee, e.g.:

– Hydropower implications of seasonal droughts

– Effects of higher ambient water temperatures on power plant cooling, especially in summer

– Water requirements for shale gas production by hydraulic fracturing

– Water requirements for biofuels development

• In some cases, there are potentials to reduce water use sensitivities, e.g., by changing power plant cooling technologies

• At the same time, water systems need energy for water pumping and often for wastewater collection and treatment

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Four Major Assessment Reports in Late 2011 Have Examined Water Use for Electricity Generation, Related to Concerns about Climate Change: 

•Water Use for Electricity Generation and Other Sectors; Recent Changes (1985-2005) and Future Projections (2005-2030). EPRI Technical Report, November 2011

•Freshwater Use by U.S. Power Plants: Electricity’s Thirst for a Precious Resource, Energy and Water in a Warming World Initiative (EW3), Union of Concerned Scientists, November 2011

•Water for Energy: Future Water Needs for Electricity in the Intermountain West, Pacific Institute, November 2011

•Effects of Climate Change on Federal Hydropower, Oak Ridge National Laboratory for DOE, draft July 2011, final forthcoming  

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Water use for electricity generation and other sectors: Recent changes (1985-2005) and future projections (2005-2030), EPRI Technical Report, November 2011.

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Water supply stresses due to demands for electricity generation and other sectors: Recent changes (1995-2005) and future projections (2050-2030), EPRI Technical Report, November 2011)

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Where power plants drive water supply stress

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Electricity demand for each water-related activity including groundwater pumping, treatment and end-use, and transmission (top-left). Electricity generation by source and their CO2 equivalent (bottom –left). Water supply delivered to the agriculture and municipal and industrial sectors (top-right), and water supply delivered by source

and the equivalent CO2 electricity equivalent for that level of generation.

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Role that shale gas plays in the coterminous U.S

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What Kinds of Responses Make Sense Now to What Kinds of Responses Make Sense Now to Reduce Current and Future Risks?Reduce Current and Future Risks?

• Reducing water consumption per capita/per unit of GDP

– Increasing water use efficiency

– Making more use of recycled water

– Reducing water consumption requirements for economic services, e.g., electricity generation

• Adding flexibility and responsiveness to water supply systems

– Increasing water storage capacity and other system redundancies

– Planning for shortages

– Increasing adaptive capacity through more flexible management

• Best management practices

• Robust and adaptive decision-making processes and institutions (e.g., removing obstacles…)

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For Examples of Innovative Water System For Examples of Innovative Water System Management, We Can Look at Some US Cities:Management, We Can Look at Some US Cities:

• Often focused on inadequate systems for handling wastewater and stormwater, examples include Philadelphia, New York’s PlaNYC, Milwaukee, Tucson, Portland, and Seattle

• For example, Philadelphia’s “Green City, Clean Waters” program is a 25-year commitment to convert more than 1/3 of the city’s impervious land cover to green facilities, along with stream corridor restoration and preservation

• Being implemented through leveraged funding from the development community as a part of every new development project

• Has catalyzed a Model Neighborhood program to encourage community participation in greening the city

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What Kinds of Responses Make Sense Now to What Kinds of Responses Make Sense Now to Reduce Current and Future Risks?Reduce Current and Future Risks?

• Some particular issues:

– Implications of surface water scarcity for groundwater withdrawals

– Implications for water quality as well as water quantity, including water system connections with changes of exposures to diseases due to climate change

– Responses to increased risks of episodic flooding:• Evaluate design standards for water and drainage systems

• Review policies for floodplain development and protection

– Potentials to improve watershed management

– Potentials for collaborative regional water system planning to address multiple stresses

– Potentials to desalinize brackish waters

What Does This Imply For Water Resource What Does This Imply For Water Resource Management in Tennessee?Management in Tennessee?

• Not yet a reason for alarm – but a call for sensible thinking about risk

– Trends toward greater variability in precipitation• In the magnitude of precipitation, especially its concentration in a

smaller number of heavy precipitation events

• In the seasonality of precipitation

– Increased water demand associated with higher temperatures and heat waves – intensifying competition for water among users

– Especially changes in extremes and/or extreme events

• A reason to look at the many possible adaptations that have been identified

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What Should We Be Doing? (I):What Should We Be Doing? (I):• Adopting risk management approaches as a strategy for

preparing ourselves for an uncertain future

– Considering a range of possible future conditions in adaptation planning

– Identifying adaptation options that would reduce vulnerabilities

– Implementing adaptations that make sense now: usually those that offer co-benefits for other objectives

– Becoming more adaptive in planning for the future

• Contingency planning for relative severe impacts

• Monitoring and research strategies to be better prepared

• Removing institutional obstacles to flexible responses to changes and surprises – test through exercises?

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What Should We Be Doing? (II):What Should We Be Doing? (II):

• Strengthening partnerships across all branches and scales of government, economic sectors, and other parts of U.S. society

– Recognizing that no one party is best at meeting every need

– Drawing on what each party does best

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Related to Broader Efforts to Promote Related to Broader Efforts to Promote Sustainable Social, Economic, and Sustainable Social, Economic, and Environmental Development in Tennessee:Environmental Development in Tennessee:

• A “Tennessee Sustainability Initiative” emerging

• A partnership involving ORNL, Vanderbilt, UT, a number of Nashville business leaders, and others

• We would be interested in establishing a link with the Tennessee AWRA

• The coordinator is Ben Preston, ORNL; the lead for the water supply/demand topic is Dan Larsen, University of Memphis, advised by George Hornberger, Vanderbilt University, and others