Coastal Drought and Water Supply in the Southeast

Transcription

1 Coastal Drought and Water Supply in the Southeast Jessica C. Whitehead, PhD. S.C. Sea Grant Consortium/N.C. Sea Grant 2010 Land Grant and Sea Grant National Water Conference 22 February 2010

2 Outline Coastal drought impacts Carolinas examples Considerations and tools for coastal water management (SC State Climatology Office 2007)

3 Coastal drought impacts: A story of salt water intrusion Mean tidal water levels Tidal range Reduced streamflow Precipitation Management actions

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5 Short Review Salinity Dynamics Riverine Flow Freshwater Saltwater Tidal Forcing water level, tidal range estuaries estuaries may never really be steady-state state systems; they may be trying to reach a balance they never achieve. Keith Dyer, from Estuaries A Physical Introduction (1997) (Conrads 2007)

6 Flows and Specific Conductance (Conrads 2010)

7 Salt water intrusion impacts Water management Well contamination Surface water intakes Treated effluent discharge (Hawes 2009)

8 Salt water intrusion impacts Ecological impacts Marsh vegetation River composition Commercially valuable species (SC DNR 2006)

9 SC Precipitation Annual Compared to Average Only 1 wet year Annual Avg (Mizzell 2008)

10 D R I E S T City of Charleston, SC Decadal Precipitation (Mizzell 2008) Year Amount of Rainfall W E T T E S T Year Amount of Rainfall

11 USGS/CISA Yadkin-Pee Dee Study 6 NC reservoirs control Pee Dee River streamflow to SC 3 water intakes along SC coast Area drought: saltwater moved upstream and limited freshwater supply Only freshwater portion of the ICW (Conrads 2007)

12 (Mizzell 2008)

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14 Flow Dynamics and Salinity Response Pee Dee River Pee Dee River Streamflows Municipal intake El Nino Specific conductance downstream of municipal intake (Conrads 2007)

15 Issues for water managers to consider Regulatory and political Reservoir re-licensing, interbasin transfers and allocations Deepening channels and harbors Management actions Timing withdrawals and releases around salinity intrusion events Increasing storage Blending higher and lower conductance sources

16 SC Drought Monitoring Tools and Applications Water Conservation Actions Drought Management Plan and Response Ordinance Inventory Dynamic Drought Index (Mizzell 2008)

17 Communicating Conservation Actions (Mizzell 2008)

18 Drought Response Plans and Ordinances (Mizzell 2008)

19 (Mizzell 2008)

20 (Mizzell 2008)

21 Existing Salinity Intrusion Models Pee Dee and Waccamaw Rivers and Atlantic Intracoastal Waterway Myrtle Beach Georgetown Lower Savannah River Estuary Beaufort Savannah Charleston (Conrads 2010)

22 (Conrads 2007, 2010) 2010 Land Grant and Sea Grant National Water Conference 22 February 2010 Pee Dee River and Atlantic Intracoastal Waterway Salinity Intrusion Model Decision Support System PRISM-DSS integrates: Historical database ANN models Model simulation controls 2D and 3D Visualization Optimization routine Simulation output Developed using Visual Basic and Excel Excel application easily disseminated

23 M2M Decision Support System Excel application Integrates Historical database River, marsh ANN models Model controls Streaming graphics Model simulation output (Conrads 2010)

24 Savannah Model Dissemination Simulation period and time step User set flows constant or percent of historical flow Harbor Water Levels Historical Flows and User-Input Flows (Conrads 2010)

25 Future Model-to-Marsh (M2M) 3D model predictions at USGS river gages used for input to the Marsh ANN models Pore-water salinity predictions interpolated to generate a 2D contour pore-water salinity grid Grid used as input to Marsh Succession Model Applications (Conrads 2010)

26 Assessing Salinity Intrusion Impacts Under Future Climatic and Sea Level Changes Four freshwater municipal intakes are in tidal waters. Will climate change increase salinity concentrations at these intakes? Collaboration between: USGS SC Water Science Center (Beaufort- Jasper Water and Sewer Authority) CISA Sea Grant (NOAA SARP) Advanced Data Mining (ADM) Myrtle Beach Georgetown Charleston Savannah Beaufort (Conrads 2010)

27 Preliminary Model Results: 7/1995 to 12/ Sea Level Rise (SLR) Frequency (days) of 2,000 µs/cm at intake: 7/ /2002: 99 d + I-ft SLR: 198 d + 2-ft SLR: 345 d Georgetown

28 Next Steps: Climate Scenario Design Climate impacts on hydrology Downscaled global climate model data Sea level rise projections Stakeholder workshops Previous project with stakeholder input informed model development Stakeholders identify other key scenario elements

29 Experimenting with user-friendly delivery (Yi 2009)

30 Summary Coastal drought: a salinity intrusion story Water management Ecological impacts SC, GA droughts demonstrated salinity intrusion problems Tools exist for communicating drought information Tools in development for future salinity intrusion

31 Special thanks to: Hope Mizzell, SC State Climatologist Paul Conrads, USGS Dan Tufford, Kirstin Dow, and Greg Carbone, CISA