Baird Claytor Hydroelectric Project Sedimentation Study

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Claytor Hydroelectric ProjectClaytor Hydroelectric ProjectSedimentation StudySedimentation Study

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Overview

I. Project Description

II. Objectives

III. Relicensing Relevance

IV. Project Tasks

V. Project Schedule

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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

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I. General Area - Claytor Watershed

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I. Claytor Lake

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I. New River to Hwy 460 Bridge, Glen Lyn

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II. Objectives1. Update surface area and storage volume curves,

2. Determine areas of sediment accumulation,

3. Determine sediment accumulation rate during existing and new license terms,

4. Determine flow modification impacts on downstream sediment dynamics, including;

1. assessment of how altered sediment dynamics affect downstream channel morphology,

2. Identify how physical changes have impacted beneficial uses,

3. and characterize attenuation in sediment impacts from Claytor Dam to Rte. 460 Bridge at Glen Lyn.

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II. Objectives, contd.5. 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.

6. Identify the sources of sediments discharging into the reservoir.

7. Investigate methods to prevent/reduce reservoir sedimentation impacts.

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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.

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IV. Project Tasks

Directly follow Objectives and Sedimentation Study Plan

Developed during the scoping and study plan drafting phase of the Claytor ILP process.

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Objective 1 Tasks

Update surface area and storage volume curves

1. Review existing curves

2. Develop new area/volume data

3. Develop new area/volume curves

4. Determine changes in area/volume

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Updated Bathymetric Data Analyses

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Smith Mountain Lake Reservoir Capacity Estimates

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Storage Capacity (1,000's acft)

Ele

vatio

n (f

t, N

VG

D)

AEP - 1964

AEP - 2006

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Objective 2 Tasks Determine areas of

sediment accumulation Compare existing and

updated storage-volume curves

Determine at what elevation storage losses occur

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Storage Capacity (1,000's acft)

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vatio

n (N

GV

D)

-600 -400 -200 0 200 400 600

1964 to 2006 Volume Change (1,000's acft)

1964

2006

Change per contour

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Task 3: Sedimentation Changes

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Generate “shoaling” maps to illustrate potential areas where sediment may be exposed at various water levels

• Upper Pool Limit

• Lower Pool Limit

• Other conditions ?

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Objective 3 Tasks

Determine sediment accumulation rate during existing and new license terms

1. Existing rates calculated from results of Objectives 2 and 6.

2. Future rates - develop hydrodynamic reservoir sedimentation model.

3. Model calibration & validation.4. Conduct sedimentation simulations

1. Existing conditions2. Future scenarios

Land use change Climatic variability / change

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Model Validation and Calibration

1. Model calibrated to measured reservoir currents

1. ADCP – spring, summer1. five units deployed,2. measure currents in all directions,3. exact location and logistics TBD

2. Reservoir levels

3. Watershed inputs (Obj. 6)

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Hydrodynamic Reservoir Model

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Hydrodynamic Reservoir Model

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Sedimentation scenarios

1. Future watershed alternatives (Obj. 6)

2. Coordination with shoreline erosion wave climate, boat traffic, etc

3. Climatic variability1. Observed period of record

1. Typical2. Extremes

4. Redistribution of sediments

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Objective 4 Tasks

Determine flow modification impacts on downstream sediment dynamics, including;

1. assessment of how altered sediment dynamics affect downstream channel morphology,

1. Standard federal methods (USGS, USFS, COE)2. Conduct field survey of river sedimentation

1. Geomorphic river condition survey2. River habitat survey3. Hydraulic and sediment transport survey

3. Determine hydrodynamic and sediment flux regime4. Characterize fluvial processes5. Characterize morphologic response

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Geomorphic survey

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Geologic controls on fluvial system

Geologic Control

w/significantTributary

Alluvial River

Geologic River

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Geomorphic survey1. Sites

1. Hydraulic controls2. Access3. Existing surveys4. Other studies

1. IFIM2. Erosion3. Water quality

2. Field reconnaissance1. Width, Depth, Area2. Slope, Length3. Sinuosity

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06/19/99

Cattle Trail

Cattle Trail

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Example of typical morphological results

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Freq. Cattle Infreq. Cattle Forest

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th D

epth

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< Upstream - - - - - - - - - - - - - - - - - - - - Downstream >

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Example of typical habitat results

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

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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)

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Hydraulics

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Channel Stability

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Objective 4 Tasks

Determine flow modification impacts on downstream sediment dynamics, including;

1. assessment of how altered sediment dynamics affect downstream channel morphology,

2. Identify how physical changes impact beneficial uses,1. Literature review2. Incorporate results from other studies3. Summarize results from VDEQ

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Objective 4 Tasks

Determine flow modification impacts on downstream sediment dynamics, including;

1. assessment of how altered sediment dynamics affect downstream channel morphology,

2. Identify how physical changes have impacted beneficial uses,3. and characterize attenuation in sediment impacts from

Claytor Dam to Rte. 460 Bridge at Glen Lyn.1. Develop mapping of field survey data2. Construct sediment flux/property profiles for along river

transect3. Construct river morphologic profiles along river transect

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Morphologic controls

Geologic Control

w/significantTributary

Alluvial River

Geologic River

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Downstream sedimentation features

Deposition patterns

• Bars

•Mid-channel

•Point bars

• Pool Deposition

• Island

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Downstream Impacts

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Changes in Sediment sizes & frequency

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Bed

rock

Sediment Size (mm)

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cy

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10%

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Site B (control)

Site A (OHV)

Site AB(downstream)

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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.

1. Literature review2. Review relevant, local media sources3. Review results from similar re-licensing projects4. Incorporate results from other Claytor studies5. Summarize results from VDEQ

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Sedimentation Impacts

http://www.focl.org/NewFiles/drawdownatpark.jpg

http://www.focl.org/NewFiles/creaoldtack.jpg

http://www.focl.org/NewFiles/siltation.jpg

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Objective 6 Tasks

Identify the sources of sediments discharging into the reservoir.

1. Develop watershed sedimentation model1. Future development scenarios2. Impervious surfaces3. Climate change / variability4. Upstream dams - Buck & Byllesby, Fries

2. Characterize erosion from upland sources3. Develop watershed sediment budget4. Summarize sources by type, frequency, and magnitude.5. Identify “hot-spots” of erosion and sediment yield

within the project area.

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Development and impervious surfaces

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Appalachian climatic variability – precipitation and streamflow

rainfall energy

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Sediment sources – Influence of dams

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Objective 6 – modeling dam influences

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Objective 6 – Erosion vs. Sedimentation

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Objective 6 – Spatial modeling

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Objective 6 – example results

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Objective 7 Tasks

Investigate methods to prevent/reduce reservoir sedimentation impacts

1. Evaluate existing sediment control measures.

2. Identify potential measures that may be adopted to reduce future sedimentation.

3. Preserve watershed resources1. Soil resources2. Aquatic ecosystems3. Reservoir longevity

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settling area with filtration

Area Reduction

broad based dip

culvert removal

Out-sloping roads

D.O

. – d

itch

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V. Sedimentation Study Schedule

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Sedimentation Study Schedule

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III. Reporting

Pre-Project Meeting in January Two interim progress reports – tentatively

scheduled for May and November, 2007. Draft final report (~Jan., 2008). Final report (~ April/May, 2008)

1. Bound

2. Digital

3. DVD’s with all data, models, results, etc.

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? Q U E S T I O N S ?? Q U E S T I O N S ?

Claytor Hydroelectric ProjectClaytor Hydroelectric Project  

Sedimentation StudySedimentation Study    

Application for New LicenseApplication for New License  

FERC Project No. 739FERC Project No. 739