Corps of Engineers Approach to Potential Sea Level and Climate Change

Transcription

1 Corps of Engineers Approach to Potential Sea Level and Climate Change Heidi P. Moritz, PE (Portland District, Technical Lead) Henri Langlois, PE (Institute Water Resources, Planning Lead) Kate White, PhD, PE (Institute Water Resources, PM) Civil Works Technical Letter Team Airports Council International North America Operations & Technical Affairs Pre-Conference Seminar 16 October 2011 BUILDING STRONG US ARMY CORPS OF ENGINEERS

2 Key issues Outline Corps climate change approach Sea Level Change Civil Works Technical Letter Some notes on potential climate exposure for airports Ideas for future action / development

3 Mainstreaming climate change adaptation means that it will be considered at every step in the project life cycle for all USACE projects, both existing and planned to reduce vulnerabilities and enhance the resilience of our waterresource infrastructure. - USACE Policy Statement 3

4 Key Issues Nonstationarity past magnitudes, frequency, rates, and patterns will not apply. Robustness Provide a framework for the analysis and adaptation irrespective of any particular number or assumption; Get away from the climate change question. Combinations Cumulative and system effects are important though we often isolate them for analyses Connectivity of critical systems and infrastructure (transportation, electrical, communication); Where are weak links and thresholds? Time Planning horizon (50 years) vs adaptation horizon (100 years) Decision-making Strategic and tiered. What could go wrong? Be cautious of down-selecting prematurely. Consider level of consequences. Acceptance We have always dealt with uncertainty (physical, social, political)

5 USACE Climate Change Approach Actionable: build on best actionable science developed by the science agencies and other experts (e.g., NOAA, USGS, USN, UK) Diverse: involve multi-disciplinary, multiagency team, exploit their diverse perspectives (vertically and horizontally integrated) Parallel: focus effort by subareas to develop in parallel rather than sequentially Refined: learn through pilots, demonstrations, and peer review to refine and update knowledge and guidance

6 Consider what design and operational assumptions may be based on historical values? Climate change undermines a basic assumption that historically has facilitated management of water supplies, demands, and risks. resilience of protective structures potential future downtime due to wind and weather patterns design thresholds and maintenance dollars required potential magnitude, frequency, and area of flooding power and transport connectivity abilities Stationarity allows us to assume that the statistical properties of hydrologic variables in future time periods will be similar to past time periods 6

7 What do we know? What don t we know? What do the pilots tell us? Guidance 7

8 Sea Level is Changing Observed sea-level trends (NOAA), Coastal Vulnerability Index (USGS), USACE Projects, and Port Tonnage on map of Population Density (Census) BUILDING STRONG 8 Graphic: Gregg US ARMY Bertrand, CORPS CENWP, OF ENGINEERS Jacksonville District

9 CWTL team member: Steve Gill, NOAA

10 EC Incorporating Sea Level Change Considerations in Civil Works Programs Three estimates of future SLC must be calculated for all Civil Works Projects within the extent of estimated tidal influence: Extrapolated trend Modified NRC Curve I Modified NRC Curve III Requires creativity, skill, time, funds to evaluate options Current guidance assigns equal probability to each curve

11 Relative Sea Level Rise (ft) Strategic and Tiered Decision-Making Based on Potential Risk of Sea Level Change Draft Establish strategic decision context Is this a small or large project? Existing or new project? What are the business line and mission areas impacted? How might these change under the high SLC curve? Are there system or cumulative effects possible? Is there potential for negative or maladaption impacts? What is the potential for significant or catastrophic consequences? (life safety, property, critical infrastructure, ecosystems) Does the project encourage public and private investment that will influence future risk? Who should be involved in the evaluation of input and potential impacts? Final Decision and Review Point Small project, no significant or system consequences. Large project, significant or system consequences. Strategic development investments, (e.g. major port expansion or flood risk reduction system upgrades), shapes future long term community development. First Decision and Review Point - Who should be involved? - How much analysis time is required? - What is the expected level of effort? Tier 1: Project Area Vulnerability to SLC Planning Steps 1 and 2 Identify problems and opportunities Inventory and forecast conditions Using high SLC curve, define future affected area and conditions which impact project. Establish impacted area for 3 epochs (20, 50, 100 years). When in the planning horizon are impacts expected to be realized? Bracket SLC within overall loading parameters. Assess coastal vulnerability index (CVI). Identify to what extent decisions made now preclude or define future actions. Using inventory and forecast methods to summarize critical infrastructure, weak links, thresholds. 40% of study area inundated; main transportation and evacuation routes impacted 25% of study area inundated; sanitary lift stations and gravity storm drainage significantly impacted 5% of study area inundated; gravity storm drainage impacted at high tide Coastal Vulnerability Index (CVI) is a function of 6 input parameters: geomorphology, coastal slope, relative SLC, shoreline erosion/accretion, mean tide range, and mean wave height. (USGS, 2000) Intermediate Decision and Review Point Using Results from Project Area Vulnerability Assessment Tier 3: Alternative Selection Considering SLC Planning Steps 5 and 6 Note that the horizontal axis is SLR and alternative viability is tied to a projected magnitude of SLC rather than a point in time. Compare Alternatives and Make a Recommendation Reassess adequacy of measures to address problems and opportunities and planning objectives. Are residual risks manageable and does a plan exist to manage them? Is the strategy sustainable? Are resources available for the system to remain viable? How do the alternatives compare given the defined performance metrics? What can go wrong, how can it happen, what are the consequences, how likely is it? Does implementation of this strategy preclude future decisions or opportunities? Small project area, SLC provides relatively small contribution within overall loading, CVI is low, robust thresholds, minimal critical infrastructure Qualitative SLC analysis; limited quantitative analysis Tier 2: Alternative Development Considering SLC Planning Steps 3 and 4 Formulate and Evaluate Alternatives Develop measures to address Problems & Opportunities with consideration of project area vulnerability to SLC. Evaluate measure adaptability to SLC. - Develop qualitative and quantitative performance metrics. - Evaluate frequency impacts from SLC. Are impacts extreme event driven or overall process driven? - Define measure stability and performance mode sensitivity to SLC. - Assess how inundation, erosion, wave attack may change with SLC. Combine measures into alternatives that are resilient to SLC over the planning horizon. Implementation strategies range between anticipatory, reactive, adaptive, and combinations of the three. Establish start and finish points at which alternatives remain viable and determine if alternatives are adaptable at the end of the planning period. Large project area, SLC provides significant contribution to overall loading, CVI is high, weak thresholds, significant critical infrastructure Significant quantitative SLC analysis required Given the potential SLC, is protection or retreat likely to be a more viable and sustainable option? Indicator value (e.g. sea level rise) Decision point based on best estimate Recorded values of indicator Tipping points: thresholds, lead times and decision points Date of review Threshold value of indicator when intervention is needed Predicted values of indicator based on rate of change Lead time for planning and construction Source: United Kingdom Climate Impacts Program Ti m e

12 Inventory and Forecast Conditions Storm Damage Reduction Magnitude and frequency changes in without project condition damages High SLC Footprint Expand data gathering to include: inundation footprint of high SLC curve critical resources (e.g. public works facilities; hospitals) Evaluate sensitivity of study area to SLC using both qualitative and quantitative analyses Baseline SLC Footprint CWTL Team members: Matt Schrader and Tom Smith

13 Stability and Performance Design Conditions H s = 4m Tp = 8 sec Water Level = 2m Armor Layer (5.3 ton) Crest Elevation 6.6m 1 2 Toe Armor (1.4 ton) -2m Underlayer (0.53 ton) Bedding Stability of a project could be influenced by cross section design or project layout characteristics. CWTL team member: John Headland

14 Future storm tides will reach higher elevations than past storms and will do so more frequently impacting both flooding and structural loading. Isabel, Sept 2003 Dr. David Kriebel, USNA 14

15 Potential Strategies of Approach for Alternatives Anticipatory Strategy Implements features now; for example, increases design parameters for engineered features Adaptive Management Strategy Uses sequential decisions and implementation based on new knowledge; implementation prior to SLC impacts. Requires advance planning to maintain the ability to adapt. Reactive Strategy Can be planned or ad-hoc, but in either case no actions would be implemented until the impacts of SLC begin PROJECT DESIGN SLC IMPACTS YEAR 50 ANTICIPATORY STRATEGY ADAPTIVE MANAGEMENT STRATEGY REACTIVE STRATEGY ADAPTIVE MANAGEMENT STRATEGY CWTL Team Members: Brian Harper, Matt Schrader, Tom Smith

16 United States Ports: Addressing the Adaptation Challenge, Mr. Mike Savonis

17 Increasing severity of climate impacts Infrastructure planned and built with past climate and weather in mind may not be adequate for future resilience and operation. United States Ports: Addressing the Adaptation Challenge, Mr. Mike Savonis

18 LaGuardia International Airport

19 United States Ports: Addressing the Adaptation Challenge, Mr. Mike Savonis

20 Water Level Elevation (ft, MLLW) Projected Extreme Water Level Excursions to 2100 Willet Point, New York (relative to present day MLLW ( NTDE) extreme low high low ft MLLW extreme high sea level change ft MLLW ft MLLW New Datum High Sea Level Change = +5.5 ft 4 2 New Datum Low Sea Level Change = +0.9 ft ft MLLW ft MLLW -3.7 ft MLLW Existing Low SLR High SLR Notes: (1) By 2110 NOAA will have updated the tidal datum 19-year epoch updates to keep pace. These plots as intended to show the adjustment relative to present day MLLW ( NTDE). (2) The extreme water level elevations shown do not include open coast extreme storm surge or wave run-up. CWTL Team Member: Steve Gill

21 Monthly Extreme above STND (ft) LaGuardia Airport New York using The Battery Tide Station Flood Threshold at +6.7 ft above MSL or ft above Station Datum Projections use NRCIII Sea Level Rise Scenario Recurrence Intervals for High Tide Events Flood Threshold MSL trend Monthly High Tides Previous MSL Trend 1 month 2 month 1 yr 5 yr 10 yr 50 yr Years from present CWTL Team Member: Dr. Dave Kriebel

22 Conceptual Ideas for Infrastructure Planning Identify cumulative and extreme events (frequency and magnitude) Accept uncertainty; don t attach approach to a specific number or theory Utilize estimated upper bounds to identify vulnerability and risk Define greater framework (time, spatial, system) Determine the strategic importance of impacts Know your system Elevations, weak links, thresholds Key economic, life safety, operation issues Assess connectivity and potential for cumulative or system effects Develop graduated levels of response; potential range of actions Identify items which are adaptable as well as items which are not Develop a reasonable timeline Don t prematurely down-select alternatives Acknowledge potential risk. What could go wrong? Develop plan which monitors new developments and can make adjustments

23 Summary of Corps of Engineers Approach Climate is changing, especially impacting weather extremes Coastal policies and guidance ahead of hydrology Collaborative efforts with other agencies help to identify long-tem and short-term user needs, and to develop consistent guidance Integrating adaptation and mitigation supports a portfolio management approach with mix of near-term and longterm actions Recent research about climate change and ecosystems encourages us to think in new ways Adaptation pilot projects increase our understanding and help ID gaps and areas where new guidance may be needed 23

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25 Additional Slides

26 SLC Civil Works Technical Letter Utilize national interdisciplinary team within Corps and include outside agency experts, addressing full range of Corps missions and project types Convey to the field the level of detail required as a function of project type, planning horizon, and potential consequences Identify the potential for adaptation throughout project life or project phasing Develop a road map that lays out the engineering and planning procedure for full range of projects Develop region-by-region information and examples Include tools that can be used to address sensitivity and communicate risk 2

27 Modified from: Extent of Resources at Risk (A Technical Review of Coastal Projects: Shore Protection, Navigation and Ecosystem Restoration for North Atlantic Division (Spring 2009) Inventory and Forecast Conditions (hypothetical example of qualitative/quantitative analysis) Critical Resources Residential/Commercial Structures Density of Resource Medium Risk to Resource from SLC Low Environment and Habitat High Medium Infrastructure (roads, water/sewer lines, etc.) Critical Facilities (police, fire, etc.) Medium Low Low Low Evacuation Routes High Medium Recreation High Low CWTL Team members: Matt Schrader and Tom Smith

28 Source: Transport Infrastructure and Network Adaptation to climate Change: Issues and Strategies for Ports, Mr. Philippe Crist, September

29 San Francisco and Oakland Airports

30 Monthly Extreme above STND (ft) San Francisco International Airport (SFO) using San Fracisco Tide Gage Flood Threshold at +5.4 ft above MSL or ft above Station Datum Projections use NRCIII Sea Level Scenario Recurrence Intervals for High Tide Events Flood Threshold Previous Future 14 MSL Trend 1 month 13 2 month 12 1 yr 5 yr Monthly High Tides yr 50 yr 9 MSL trend Years from present CWTL Team Members:

31 USACE Mission Areas Affected by SLC Navigation Breakwaters and Jetties Harbors Navigation Channels and Ocean Disposal Sites Coastal Storm Damage Reduction Beach fills Shoreline protection structures Flood Damage Reduction Dams, levees, floodwalls Water Supply Ecosystem Restoration Emergency Response Recreation

32 SLC CWTL is part of an integrated programmatic effort - some elements are shown here IPET/HPDC Lessons Learned Implementation Team (FY06 ) Responses to Climate Change (FY10-14) Global Change Sustainability (FY11-20) Nationwide Datum Standard EC, ER, EM, Comprehensive Evaluation of Project Datums Engineer Circular Sea-Level Change CWTL Comprehensive Evaluation of Projects With Respect to Sea Level Change

33 Note that the horizontal axis is SLR and alternative viability is tied to a projected magnitude of SLC rather than a point in time. This figure is based on a United Kingdom approach to evaluating alternatives against the RSLR.