Aurora Water Resources Planning A Pragmatic Approach for Incorporating Uncertainty

Transcription

1 Aurora Water Resources Planning A Pragmatic Approach for Incorporating Uncertainty Presented by Brian Fitzpatrick, Aurora Water Chip Paulson, MWH Americas, Inc. AWRA 2015 Spring Specialty Conference Water for Urban Areas: Managing Risks and Building Resiliency

2 Presentation Outline Introduction to Aurora, Colorado raw water system Water supply planning under uncertainty Tools for water resources analysis Strategies for planning The future ain t what it used to be. - Yogi Berra

3 INTRODUCTION TO AURORA, COLORADO AND THE INTEGRATED WATER MASTER PLAN When the well is dry, we know the worth of water. -Benjamin Franklin

4 City of Aurora, Colorado 3 rd largest city in the state for now Population 354,000 (2015) Home to Buckley Air Force Base and the Gateway to the Rockies! Aurora Colorado Springs

5 COLORADO RIVER BASIN 21,441 Homestake Reservoir 15,000 5,000 Turquoise Lake 2,721 VAIL Twin Lakes LEADVILLE Aurora Water Supply System FAIRPLAY 2,167 Jefferson Lake 49,651 Spinney Mountain Reservoir DENVER Rampart Reservoir Strontia Springs Reservoir Cheeseman Reservoir 4,688 Griswold WTP Quincy Reservoir Wemlinger WTP AURORA Aurora Reservoir 31,679 SOUTH PLATTE RIVER BASIN BUENA VISTA 3 river basins 9 reservoirs Water brought from up to 200 miles away Storage Capacity (Acre Feet) COLORADO SPRINGS ARKANSAS RIVER BASIN 10,000 9,117 PUEBLO Pueblo Reservoir ROCKY FORD Lake Meredith Total Storage Capacity 156,400AF

6 Water Supply Crisis 26% of System Storage

7 Aurora Water Conservation Program has reduced demands Xeriscaping Rebate programs Education and outreach

8 Aurora Water Drought Response Program new drought stage chart 100% Indoor Demand + 80% Outdoor Demand 100% Indoor Demand + 50% Outdoor Demand 100% Indoor Demand Only

9 Not all IWRPs are integrated in the same way Integrated across disciplines(e.g., hydrology, water quality, environmental) Integrated across geographies(e.g., watersheds, groundwater basins, entities) Integrated across system components (e.g., supply, water treatment, distribution, wastewater treatment) Integrated across agency departments (e.g., Planning, Engineering, Operations) When we try to pick out anything by itself, we find it attached to everything else in the universe. - John Muir

10 What is Integrated in the Aurora IWMP? System Components 6

11 AURORA WATER S APPROACH TO PLANNING UNDER UNCERTAINTY If anything is certain, it is that change is certain. The world we are planning for today will not exist tomorrow. Peter Drucker

12 Transition from Traditional Planning: Demand Supply System Conditions We don t know what we need to know to do it the old way

13 Demand is uncertain Aurora s 2070 demand forecasts vary by 38%

14 Supply is uncertain Colorado River flows show a decreasing trend Global climate models show hotter temperatures and range of precipitation changes by 2050

15 System Conditions are uncertain Risks, Threats and Vulnerabilities Aging Infrastructure Outages / Deferred Maintenance Water Administration (interstate compacts) Environmental Regulations Natural Hazards (wildfire, floods) Risk, like beauty, is in the eye of the beholder. - Dennis Mileti, Director of Natural Hazards Research Applications and Information Center

16 Scenario-or ensemble-based planning incorporates uncertainty Traditional Planning One target (one population forecast, one demand forecast, one hydrologic sequence) One solution (one set of projects, one implementation plan) Goal: Find the optimal solution to address the most likely potential future Scenario-or Ensemble-Based Planning Range of targets (variable demand forecasts, variable future hydrologic conditions) Range of potential solutions (Robust strategic plan, decision-tree approach) Goal: Find a robust solution(s) to address the broadest range of potential futures

17 Building Planning Scenarios for Aurora Water Building Blocks Descriptions Demand Forecasts Moderate Growth 95,300 ac-ft/yr in 2070 Fast Growth 130,200 ac-ft/yr in 2070 Hydrology Ensembles Current Climate 50 stochastic traces based on tree-ring reconstructions Hotter/Drier Climate 50 selectively drier traces based on GCM results Conservation Programs Current Current measures Expanded Additional cost-effective measures System Risks No Risks No failures or outages 9 Risks System component failures and yield reductions

18 Building Planning Scenarios for Aurora Water Baseline Plus Fast Growth Scenarios Hot and Fast Hot Baseline Building Blocks Demand Forecasts Moderate Growth X X Fast Growth X X Hydrology Ensembles Current Climate X X Hotter/Drier Climate X X Conservation Programs Current Expanded X X X X System Risks No Risks X X X X 9 Risks X X X X

19 Aurora s scenario approach Not too simple, not too complex 1 Future All Combos Aurora: 2 demand forecasts 2 conservation programs 100 hydrologic sequences (50 traces x 2 climates) 9 system risks

20 TOOLS, METHODS AND A FEW RESULTS We are drowning in data but starving for understanding. - Marcia McNutt, USGS Director

21 We have complex data management and modeling systems Baseline Conditions Performance Metrics Historical Climate Change Paleo Hydrology Generation Identified Risks 5x IWMP SQL Database Data Management System (DMS) Preprocessing? New Functionality CRAM System Model Demand Generation Results Processing & Analysis Aurora Modeling System

22 We have adopted multiple metrics to assess system performance How often do shortages occur? How severe are the shortages? How long are the shortages? How deep is the worst shortage? All these replace the traditional firm yield (100% reliability)

23 Metrics are calculated based on total reservoir system storage Resilience How Long Vulnerability How Bad Reliability How Often

24 Specific metrics and performance goals for Aurora Water system Performance Metric Total Demand Reliability Definition Probability of meeting full customer demands Assumed Demands to Be Met Total system demands Acceptability Threshold (80%) Minimum Short- Year Supply Reduced Demand Reliability Storage Reliability Minimum supply as a percent of total demand Indoor demands 0.60 (60%) Probability of meeting Reduced system 1.0 (100%) reduced customer demands based on demands with drought drought response response watering stages restrictions Probability of being above the thresholds for the following storage levels at the beginning of any particular month: Severely Dry (Stage I) 100% Indoor + 80% Outdoor Extremely Dry (Stage II) Emergency Conditions (Stage III) 100% Indoor + 50% Outdoor 0.80 (80%) 0.95 (95%) 100% Indoor only 0.99 (99%)

25 Sample Results Water Needs by Scenario Year in which Critical Gap Begins for All Planning Scenarios and a Range of Hydrologic Acceptability Goals

26 Sample Results -Effect of System Risks on Water Needs

27 Dual Metric Performance Plots Stage 1 Storage Reliability vs Minimum Supply Baseline Plus Scenario - Moderate Growth - Current Hydrology Fast & Hot Scenario - Fast Growth - Hotter/Drier Hydrology

28 STRATEGIES FOR PLANNING Everyone has a plan til they get punched in the mouth. Mike Tyson

29 Planning Strategies Flexibility and Storage No Regrets Strategies -Short-term actions that preserve long-term options Flexibility Diversified portfolios Storage Existing System Efficiencies Reuse New Supplies Conservation Agricultural Water Leases

30 Assessment of Projects and Portfolios Acceptable Range using Metrics Acceptability Threshold Acceptability Threshold Acceptability Threshold 4 Scenarios for Baseline conditions -No scenarios have acceptable performance Add projects in Portfolio #1-1 scenario has acceptable performance Add projects in Portfolio #2-3 scenarios have acceptable performance

31 It s all about tradeoffs Water managers will have to make tough choices Increased System Reliability (Fewer Restrictions) Low Cost of Service (Lower Rates) We can help by quantifying the tradeoffs

32 The Critical Integrator - Consensus Without it, nothing will get done Getting there is often more difficult than solving the technical problems The right process assures all voices are heard

33 Where we are on the journey of water resources planning under uncertainty Development of System Model and DMS DONE Selection of Metrics DONE Vulnerability Assessment DONE Water Needs Assessment DONE Evaluation of Potential Solutions IN PROGRESS Selection of Portfolio(s) COMING SOON

34 In Summary Make choices about what to integrate Embrace the uncertainty Percent of Traces Meeting Acceptability Threshold Reduced Supply-Reliability STO-Severely Dry-Reliability Minimum Supply Total Supply-Reliability Hydrologic Acceptability Threshold Annual Demand (1,000 ac-ft) Planning Gap Critical Gap Year Annual Demand Demand Level for Critical Gap Demand Level for Planning Gap Get a big computer we have the tools Quantify the policy choices

35 THANK YOU! Prediction is difficult, especially about the future. Yogi Berra

36 Determining Water Needs Percent of Traces Meeting Acceptability Threshold 100% Reduced Supply-Reliability STO-Severely Dry-Reliability Minimum Supply Total Supply-Reliability 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 150 Hydrologic Acceptability Threshold Annual Demand (1,000 ac-ft) Year Annual Demand Demand Level for Critical Gap Demand Level for Planning Gap Critical Gap Planning Gap

37 Determining Water Needs