Claytor Hydroelectric Project Sedimentation Study

1. Claytor Hydroelectric ProjectSedimentation Study

2. Baird Overview I. Project Description II. Objectives III. Relicensing Relevance IV. Project Tasks V. Project Schedule

3. Baird I. Project Description The proposed tasks are specifically designed to meet the objectives of the Sedimentation Study Plan for Claytor Lake and the integrated licensing process. They include; • bathymetric analyses, • watershed sedimentation models, • watershed, river, and reservoir field surveys, • reservoir sedimentation models, • literature reviews

4. I. General Area - Claytor Watershed

5. I. Claytor Lake

6. I. New River to Hwy 460 Bridge, Glen Lyn

7. II. Objectives • Update surface area and storage volume curves, • Determine areas of sediment accumulation, • Determine sediment accumulation rate during existing and new license terms, • Determine flow modification impacts on downstream sediment dynamics, including; • assessment of how altered sediment dynamics affect downstream channel morphology, • Identify how physical changes have impacted beneficial uses, • and characterize attenuation in sediment impacts from Claytor Dam to Rte. 460 Bridge at Glen Lyn.

8. II. Objectives, contd. • Identify the extent of problems associated with the accumulation of sediments within the reservoir and downstream of the dam, including impacts on recreation, the fisheries, and aesthetics. • Identify the sources of sediments discharging into the reservoir. • Investigate methods to prevent/reduce reservoir sedimentation impacts.

9. III. Project Re-licensing Relevance Sedimentation within the project reservoir and downstream river can have a significant impact on recreational uses, shoreline development, and project generation. Identification of where sediment accumulation may be most pronounced will provide information relative to the development of potential control measures, if needed.

10. Baird IV. Project Tasks • Directly follow Objectives and Sedimentation Study Plan • Developed during the scoping and study plan drafting phase of the Claytor ILP process.

11. Objective 1 Tasks Update surface area and storage volume curves • Review existing curves • Develop new area/volume data • Develop new area/volume curves • Determine changes in area/volume

12. Updated Bathymetric Data Analyses

14. Objective 2 Tasks • Determine areas of sediment accumulation • Compare existing and updated storage-volume curves • Determine at what elevation storage losses occur

15. Task 3: Sedimentation Changes

16. Generate “shoaling” maps to illustrate potential areas where sediment may be exposed at various water levels • Upper Pool Limit • Lower Pool Limit • Other conditions ?

17. Objective 3 Tasks Determine sediment accumulation rate during existing and new license terms • Existing rates calculated from results of Objectives 2 and 6. • Future rates - develop hydrodynamic reservoir sedimentation model. • Model calibration & validation. • Conduct sedimentation simulations • Existing conditions • Future scenarios • Land use change • Climatic variability / change

18. Model Validation and Calibration • Model calibrated to measured reservoir currents • ADCP – spring, summer • five units deployed, • measure currents in all directions, • exact location and logistics TBD • Reservoir levels • Watershed inputs (Obj. 6)

19. Hydrodynamic Reservoir Model

20. Hydrodynamic Reservoir Model

21. Sedimentation scenarios • Future watershed alternatives (Obj. 6) • Coordination with shoreline erosion • wave climate, boat traffic, etc • Climatic variability • Observed period of record • Typical • Extremes • Redistribution of sediments

22. Objective 4 Tasks Determine flow modification impacts on downstream sediment dynamics, including; • assessment of how altered sediment dynamics affect downstream channel morphology, • Standard federal methods (USGS, USFS, COE) • Conduct field survey of river sedimentation • Geomorphic river condition survey • River habitat survey • Hydraulic and sediment transport survey • Determine hydrodynamic and sediment flux regime • Characterize fluvial processes • Characterize morphologic response

23. Geomorphic survey

24. Geologic controls on fluvial system Alluvial River Geologic Control w/significant Tributary Geologic River

25. Geomorphic survey • Sites • Hydraulic controls • Access • Existing surveys • Other studies • IFIM • Erosion • Water quality • Field reconnaissance • Width, Depth, Area • Slope, Length • Sinuosity

26. < Upstream - - - - - - - - - - - - - - - - - - - - Downstream > Example of typical morphological results

27. Example of typical habitat results For illustrative purposes only, actual habitat survey methods and results may be coordinated with other studies.

28. Hydraulics & stability • Number of methods • Hydraulic analyses • WIN-XSPRO • SIAM (U.S. Corps of Engineers) Sediment Impact Assessment Model • Stability analyses • WIN XSPRO • Channel Stability Tool • SIAM (U.S. Corps of Engineers)

29. Hydraulics

30. Channel Stability

31. Objective 4 Tasks Determine flow modification impacts on downstream sediment dynamics, including; • assessment of how altered sediment dynamics affect downstream channel morphology, • Identify how physical changes impact beneficial uses, • Literature review • Incorporate results from other studies • Summarize results from VDEQ

32. Objective 4 Tasks Determine flow modification impacts on downstream sediment dynamics, including; • assessment of how altered sediment dynamics affect downstream channel morphology, • Identify how physical changes have impacted beneficial uses, • and characterize attenuation in sediment impacts from Claytor Dam to Rte. 460 Bridge at Glen Lyn. • Develop mapping of field survey data • Construct sediment flux/property profiles for along river transect • Construct river morphologic profiles along river transect

33. Morphologic controls Alluvial River Geologic Control w/significant Tributary Geologic River

34. Downstream sedimentation features • Deposition patterns • Bars • Mid-channel • Point bars • Pool Deposition • Island

35. Downstream Impacts

36. Changes in Sediment sizes & frequency

37. Objective 5 Tasks Identify the extent of problems associated with the accumulation of sediments within the reservoir and downstream of the dam, including impacts on recreation, the fisheries, and aesthetics. • Literature review • Review relevant, local media sources • Review results from similar re-licensing projects • Incorporate results from other Claytor studies • Summarize results from VDEQ

38. Sedimentation Impacts http://www.focl.org/NewFiles/siltation.jpg http://www.focl.org/NewFiles/drawdownatpark.jpg http://www.focl.org/NewFiles/creaoldtack.jpg

39. Objective 6 Tasks Identify the sources of sediments discharging into the reservoir. • Develop watershed sedimentation model • Future development scenarios • Impervious surfaces • Climate change / variability • Upstream dams - Buck & Byllesby, Fries • Characterize erosion from upland sources • Develop watershed sediment budget • Summarize sources by type, frequency, and magnitude. • Identify “hot-spots” of erosion and sediment yield within the project area.

44. Development and impervious surfaces

45. Appalachian climatic variability – precipitation and streamflowrainfall energy

46. Sediment sources – Influence of dams

47. Objective 6 – modeling dam influences

48. Objective 6 – Erosion vs. Sedimentation

49. Objective 6 – Spatial modeling

50. Objective 6 – example results