1. Salinity Intrusion: Integrating Riverine and Coastal Forces Paul Conrads U. S. Geological Survey SC Water Science Center Columbia, SC NIDIS Carolinas Pilot Project Scoping Workshop July 31, 2012

2. Outline Conceptual model of salinity intrusion Conceptual model of salinity intrusion Look at some data Look at some data Drought and salinity intrusion Drought and salinity intrusion Coastal drought index and data resource Coastal drought index and data resource Summary Summary

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

4. Saltwater-Freshwater Interface High flows Low water levels Tidal Marshes Critter Communities

5. Saltwater-Freshwater Interface Low flows High water levels Tidal Marshes Critter Communities

6. Example of Data: Yadkin-Pee Dee Basin Freshwater Saltwater Riverine Flow Tidal Forcing mean water level, tidal range Flow: Pee Dee River at Pee Dee Water level and Tidal Range: Atlantic Intracoastal Waterway at Little River Inlet Specific conductance (salinity): Waccamaw River the Hagley Landing

7. Example of Data: Streamflow Freshwater Saltwater Riverine Flow Tidal Forcing mean water level, tidal range

8. Example of Data: Water level Freshwater Saltwater Riverine Flow Tidal Forcing mean water level, tidal range Two signals: Mean water level & Tidal Range Tide Range Mean Water Level

9. Water Level and Tidal Range

10. Pee Dee River Flows

11. Waccamaw River Specific Conductance

12. Flows and Specific Conductance

13. SPECIFIC CONDUCTANCE, UG/CM and FLOW, FT 3 /S GAGE HEIGHTS AND FILTERED GAGES HEIGHT, FEET Converging Conditions

14. Looking Inside the Black Box 3D response surfaces 3D response surfaces Surface created by model Surface created by model “Unseen” variables set to constant value “Unseen” variables set to constant value Manifestation of historical behavior of system Manifestation of historical behavior of system Insight to the process dynamics or physics Insight to the process dynamics or physics

15. What Conditions Cause Large Intrusions? High water Low water 3-D Response surface – Flow, Tidal Range, and Salinity Salinity > Flow > Tide range > Low Coastal Water Level High Coastal Water Level

16. Savannah River Riverine Flows Savannah River at Clyo Tidal Forcing Mean Water level Tidal Range Fort Pulaski Freshwater Saltwater Specific conductance I-95

17. Savannah River at I-95

18. Converging Conditions: Savannah River

19. Flow and Drought Index Very quick look at South Carolina Coast Weekly drought index for Marion County Plot with 7-day average flow & 7-day average specific conductance

20. Flow and Drought Index D4 D3 D2 D1 0-D0

21. Specific Conductance and Drought Index D4 D3 D2 D1 0-D0

22. Data Resource – USGS Real-time Network

23. USGS Coastal Carolina Real-time Network ~50 active gages: Parameters: water level, sp. cond., temperature, dissolved oxygen, turbidity, pH, and/velocity

24. Summary Salinity dynamics results of flow and coastal water interaction Salinity dynamics results of flow and coastal water interaction Salinity intrusion events caused by convergence of conditions Salinity intrusion events caused by convergence of conditions Potential of a salinity coastal drought index Potential of a salinity coastal drought index Real-time data networks available to support potential coastal drought index Real-time data networks available to support potential coastal drought index

25. Paul Conrads USGS South Carolina Science Center pconrads@usgs.gov

26. Fast Forward FERC Re-licensing

27. AIW/North End Salinity

28. Example of Data: Streamflow Freshwater Saltwater Riverine Flow Tidal Forcing water level, tidal range

30. Convergence of Conditions

31. Orbital Mechanics and Tide Range Neap TidesSpring Tides

32. Tidal Range and Specific Conductance

33. Water Level and Specific Conductance

34. Converging Conditions: South End – Waccamaw River