Metro Water District Climate Utility Resiliency Study

Transcription

1 Metro Water District Climate Utility Resiliency Study Danny Johnson Manager Metropolitan North Georgia Water Planning District October 5, 2016

2 Outline Metro N. GA Water Planning District Overview Goals of Utility Climate Resiliency Study Potential Future Climate Scenarios Methodology and Findings for Vulnerability Analysis: Water Demand Impacts Water Supply Impacts Water Quality Impacts Watersheds: Flooding / Pollutant Loading Infrastructure Adaptation Summary

3 Regional Water Resources Plans Water Supply & Water Conservation Plan Wastewater Management Plan Watershed Management Plan

4 Regional Water Resources Plans Metro Water District develops regional plans Local governments responsible for implementing plans Georgia EPD approves plans and enforces implementation via permits

5 Goals of Utility Climate Resiliency Study Produce a plan for the District that can be used to guide future planning efforts Assess potential vulnerability of water resources and related infrastructure given potential climate conditions in the future: Not Predictive: The purpose was NOT to predict future climate conditions or the likelihood that certain conditions could occur. Readiness: The purpose WAS to identify potential climate conditions that, if they do occur, could create specific risks.

6 Representative Summary of Climate Scenarios 5 representative scenarios of possible future climate conditions based on GCMs HOT/DRY HOT/WET 1 additional scenario developed by extending historic records through WARM/DRY WARM/WET

7 Future Climate Scenarios: Methodology Climate Model Scenario Methodology: Delta method Adjusting 50 year historical record ( ) to reflect 2050 projections for each ensemble Maintains observed climate patterns, change factors based on modeled vs. modeled relative changes (reduces bias) End result is 5 sets of 50 year adjusted historical climate records

8 Annual Average Temperature ('F) Future Climate Scenarios: Annual Temperature Central Tendency 2050 Hot/Dry 2050 Hot/Wet 2050 Warm/Dry 2050 Warm/Wet 2050 Historical Trend Historical Observed Also have daily data to assist with looking at seasonal trends Range of Annual Temperature Change: 1 to 7 ºF Year

9 AnnualPrecipitation (in) Future Climate Scenarios: Annual Precipitation Central Tendency 2050 Hot/Dry 2050 Hot/Wet 2050 Warm/Dry 2050 Warm/Wet 2050 Historical Trend Historical Observed Range of Annual Precipitation Change: -2 to +11 in/yr Year

10 WATER DEMAND IMPACTS

11 Water Demand (MGD) Analysis of Water Demands: DeKalb, Fulton and Gwinnett Counties as Proxy Level 1 Drought Restrictions Level 4 Drought Restrictions GA Water Stewardship Act Economic Recession Dry Periods Wet Periods

12 Water Demand: Sensitivity to Climate via Multivariate Regression

13 Potential Impacts of Climate Variability: Per Capita Water Use (by 2050)* * Average increase, with all other factors unchanged.

14 WATER SUPPLY IMPACTS

15 Future Climate Scenarios: Droughts Key Message: Tendency toward increased drought conditions Summary of Mann-Kendall Drought Analysis: Atlanta, Projection Avg PDSI Avg Drought Condition Avg PDSI Avg Drought Condition Historical Observed ( ) near normal Central Tendency incipient dry mild drought Hot/Dry mild drought extreme drought Warm/Dry incipient dry mild drought Hot/Wet near normal incipient dry Warm/Wet 0.24 near normal 0.21 near normal Up to Extreme Drought Severe Drought Moderate Drought Mild Drought Incipient Drought Near Normal Incipient Wet Wet Spell Unusual Wet Spell Very Wet Spell Extreme Wet Spell 2050 to 2100 Palmer Index

16 Methods to Evaluate: Water Supply Vulnerability Reservoir County Storage Volume (BG) Drainage Area (sq.mi.) Percent watershed developed Estimated Average Flow (cfs) Dog River Reservoir Douglas Randy Poynter Reservoir Rockdale Long Branch Reservoir Henry Gardner Reservoir Henry Upper Towiliga Reservoir Henry Estimate the potential impacts of future climate scenarios on Reservoir Firm Yield Use a range of physical/hydrologic features to examine specific indicators of risk Identify the types of climate trends that could create risk

17 FIRM YIELD (MGD) Relationship Between Precipitation and Yield 35 Potential Impacts of Climate Trends on Firm Yield Dog River Randy Poynter Gardner Long Branch Cole/Tawiliga Central Tendancy Hot Dry Hot Wet Warm Dry Warm Wet Trend Projection Historic

18 WATER QUALITY IMPACTS

19 Methods to Evaluate: Water Quality Vulnerability Select Watersheds Simulate DO: Existing GA DOSAG Models

20 Water Quality Modeling Results: Water Temperature

21 Water Quality Modeling Results: Dissolved Oxygen

22 WATERSHEDS: FLOODING / POLLUTANT LOADING

23 Methods to Evaluate: Flooding Vulnerability Land Use Flint River Watershed 268 sq. mi. Yellow River Watershed 127 sq. mi. Residential 35% 60% Agriculture 14% 1% Commercial/ Industrial 8% 18% Forest 24% 8% Other 18% 13%

24 Percent Change in Rainfall Depth Projected Percent Changes in ARI Depths 15% 12% 10% 5% 0% 4% 2% 4% 4% 0% 2% 9% 5% 7% 8% 5% 7% 6% 0% 2% 5% 2% 8% 2% 5% 10% 3% 6% 8% 3% 5% 1% 9% 4% 1% 6% -2% -2% -1% -5% 1-day 2-day 3-day 4-day 1-day 2-day 3-day 4-day 1-day 2-day 3-day 4-day -4% 5-year recurrence 10-year recurrence 25-year recurrence Hot/Dry Median Warm/Wet

25 Estimated Changes in Peak Streamflows

26 INFRASTRUCTURE & ADAPTATION

27 Water Facilities Risk Scorecard Example: Wastewater Treatment Plants

28 Example of Adaptation Recommendations

29 Summary Most Severe Climate Impacts: Hot/Dry scenario Most Specific Infrastructure Risks: Hot/Wet scenario Near-term recommendations include: Establish climate tracking protocols and identify trigger levels for adaptive measures. Incorporating preemptive adaptation measures Green infrastructure Drought Management Plans

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