Appendix E2 - carrierzonetroutlakehydro.ca.previewc40.carrierzone.com/website/E2ESTA.pdf · flow,...

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Appendix E2 Erosion and Sediment Transport Assessment (Includes HEC-RAS Water Level Simulations)

(Hatch 2012a)

Horizon Hydro Inc. - Trout Lake River Hydro Project Appendix E

Erosion and Sediment Transport Assessment

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Project Report March 2012

Horizon Hydro Inc.

Trout Lake River Hydro Project

DISTRIBUTION Horizon Hydro Inc.

Larry King Ross Zhou

Appendix E Erosion and Sediment Transport Assessment

Table of Contents

1. Introduction ............................................................................................................................................ 5

2. Background ............................................................................................................................................. 5

3. Topographic Surveys ............................................................................................................................... 5

4. Sediment Data Collection ....................................................................................................................... 7

4.1 Ponar Sampling (River-Bottom Sediment) ....................................................................................... 7 4.2 Shovel Sampling (Shoreline Soils) .................................................................................................. 9 4.3 Laboratory Results ........................................................................................................................ 10

5. Water Level Simulations ........................................................................................................................ 10

5.1 Methodology ............................................................................................................................... 10 5.2 Development of HEC RAS Geometry Model ................................................................................ 11 5.3 Simulation Scenarios .................................................................................................................... 12 5.4 Results ......................................................................................................................................... 13

6. Erosion Assessment ............................................................................................................................... 16

6.1 Shoreline Erosion Assessment Methodology ................................................................................. 16 6.2 Sediment Transport Assessment Methodology .............................................................................. 16 6.3 Sediment Continuity .................................................................................................................... 17 6.4 Computing Transport Capacity ..................................................................................................... 17 6.5 Grain Size Distribution................................................................................................................. 19 6.6 Results of HEC-RAS Erosion Simulations ...................................................................................... 20 6.7 Results of Shoreline Erosion Assessment ....................................................................................... 20 6.8 Sediment Transport Analysis ........................................................................................................ 20

7. Reservoir Sedimentation Assessment ..................................................................................................... 23

8. Summary ............................................................................................................................................... 24

9. References: ............................................................................................................................................ 25



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Appendix A Head Pond Sediment/Soil Collections Appendix B HEC RAS Cross Sections



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List of Tables

Table 4.1 Petite Ponar Sampling .......................................................................................................... 9 Table 4.2 Shovel Sampling ................................................................................................................... 9 Table 4.3 Sample Analysis Summary .................................................................................................. 10 Table 5.1 Rating Table for Overflow Spillway at Big Falls .................................................................. 12 Table 5.2 Pre-Development Conditions Simulation Results ................................................................ 13 Table 5.3 Post-Development Conditions Simulation Results ............................................................... 14 Table 6.1 Estimated Peak Discharge for Trout Lake River at Big Falls ................................................. 21 Table 7.1 Shear Stresses Comparison ................................................................................................. 23

List of Figures

Figure 3.1 Location of Bathymetric and Water Level Surveys ................................................................ 6 Figure 4.1 Sediment Sampling Locations ............................................................................................... 7 Figure 4.2 Eastern Shore Erosion Area ................................................................................................... 8 Figure 4.3 Island Erosion Area ............................................................................................................... 8 Figure 5.1 Water Level Comparisons Between Pre- and Post-Development Conditions ....................... 15 Figure 5.2 Flow Velocity Comparisons ................................................................................................ 15 Figure 6.1 Hydrograph for Trout Lake River Above Big Falls ............................................................... 22



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Blank back



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1. Introduction Horizon Hydro Inc. (Horizon) submitted a Plan of Development in February of 2007 to the Ministry of Natural Resources (MNR) for the development of a 3.5-MW hydroelectric plant on Trout Lake River. Hatch Ltd. (Hatch) has been retained by Horizon to provide engineering services for the development of the plant. The plant will be located at Big Falls, Ontario, on Trout Lake River. Big Falls is located in the Kenora District of the Northwest Region of Ontario, Township of Gerry. Trout Lake River flows south out of Trout Lake and drains 2370 km2 at Big Falls.

This report addresses the following information requirements:

• simulation of pre- and post-project water levels and flow velocities at three flows (summer low flow, proposed turbine flow, and 2-yr event) using the HEC-RAS model

• analysis of shoreline erosion potential due to flow and wind generated waves, and

• analysis of sediment transport during the 2-yr flood event for the reach upstream of the proposed dam.

2. Background The drainage basin at Big Falls (2370 km2) has the presence of several lakes of which Trout Lake (376 km2) is the largest. The lakes comprise 29% of the total drainage basin area. The lake storage attenuates the peak runoff from precipitation events. The peak flow for the 2-yr flood event is 42 m3/s.

The basic scheme of the hydroelectric development is a run-of-river plant. Head-pond levels will be regulated by a fixed crest weir located just upstream of the crest of Big Falls. The overflow weir will have a crest elevation of 370.5 m. This provides an estimated weir height of about 5 m.

3. Topographic Surveys Initially, a LIDAR survey was undertaken in 2007 by Digital World Mapping to provide a detailed topographic map of the study area (i.e. shoreline contours/topography) within the proposed head pond reach, at the falls, and in the downstream reach. The readings provided an accuracy of 10 cm in elevation and 30 cm in the horizontal direction. Topographic and bathymetric survey information was then gathered at the site in the vicinity of the proposed dam and in the downstream reach during 2009 by Global Surveying Services. Trow Geomatics undertook a bathymetric survey in the head pond and the reach extending beyond the South Channel falls in 2010-2011 to provide information for the remainder of Trout Lake River project area. Nine river cross sections were surveyed in the 0.7 km upstream reach, and 26 cross sections were surveyed downstream. The location of the various sections is shown in Figure 3.1. The topographic data is based on UTM Zone 15 coordinates and NAD 83 CSRS datum.

THUNDER BAY, ONTARIO

SITE PLANSITE PLAN



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4. Sediment Data Collection To provide data for reservoir sedimentation and shoreline erosion analysis, sediment samples were collected in the head pond reach and below the falls during August 2010. Sampling locations area shown in Figure 4.1, while details of the sediment sampling program are reported in Appendix A. A summary of the main results is presented below.

4.1 Ponar Sampling (River-Bottom Sediment) In total, 12 petite ponar locations were sampled with 8 being successful in obtaining a sample.

Figure 4.1 Sediment Sampling Locations

Figure 4.1 shows the sampling locations. Sampling location P1 was located mid-channel in the head pond reach where flows from an upstream rapids had began to dissipate. Two attempts were made at the same location, with each resulting in a large piece of gravel jamming open the jaws of the ponar. The gravel was approximately 3 cm in diameter. Sed-1 was a mid-channel location farther



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downstream where flows had dissipated significantly, with velocity estimated at <0.1 m/s. A fine sediment sample was obtained at that site. Sed-2 was located mid-channel within a narrower portion of the pool above Big Falls rapids. Two sampling attempts were made, with the first hindered by a small stick jamming the jaws which resulted in the loss of the majority of the sample. The second attempt resulted in complete closure of the ponar and a sample retained. Location P2 was a mid-channel within the main flow path leading to the crest of Big Falls. No sample was collected, but as at P1, a few pieces of gravel were present within the ponar. Sed-3 was slightly east of the main flow path, where an upstream point creates a current break. A large sample of fine sediment was collected during the first attempt.

Downstream of Big Falls within the outlet area from the northern channel, there are two erosion areas: one on the eastern shore opposite the flow from the falls, (Figure 4.2) and the other located on the eastern shore of the island which separates the North and South Channels of Big Falls(Figure 4.3). A cross channel transect of four samples (Sed 4-7) were collected from one erosion area to the other, through a relatively deep pool with swirling currents. Locations 4,5,and 7 resulted in samples on the first attempt, while Location 6 took three attempts due to debris from fallen trees preventing the ponar from closing completely.

Figure 4.2 Eastern Shore Erosion Area Figure 4.3 Island Erosion Area

Sample Sed-8 was taken in an area where flows appeared to be slow due to fallen trees acting as a current break (area could be a deposition area for the eroded banks found upstream). Below the South Channel, Location P3 was attempted in an area which had more depth than the surround shallower bedrock substrate. Two attempts were made, which resulted in two samples of entirely (100%) small woody debris, consisting of small pieces of wood, bark and twigs, with no soil present. Location P4 took place on a shallower shoal downstream after the two channels reconnect and flow was uniform. Sparse aquatic vegetation was present on the shoal, which was subsequently determined to be primarily gravel after several attempts at obtaining a sample. Observations collected during the sampling are summarized in Table 4.1.



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Table 4.1 Petite Ponar Sampling

Sample ID Depth of Water (m)

Attempts Substrate Notes

P1 2.5 2 Coarse Gravel Gravel jammed jaws Sed 1 3 1 Fine Sands None Sed 2 3.5 2 Muck/Clay Twig in jaws P2 3 2 Gravel Hard packed gravel Sed3 2 1 Muck/Clay Soft substrate Sed 4 2.5 1 Clay Steep bank/erosion area Sed 5 0.5 1 Clay Just below water on steep

erosion area Sed 6 1.5 3 Clay Fallen trees from island due to

erosion Sed 7 4.5 1 Clay/Sand/Organic Deep hole Sed 8 2.5 2 Clay Trees creating current break P3 5 2 Woody Debris on

Bedrock No soil all woody debris

P4 2 2 Gravel Spare aquatic vegetation

4.2 Shovel Sampling (Shoreline Soils) Shovel sampling of shoreline soils occurred within the proposed inundation area. In total, 6 samples were collected located on the east and west shores opposite the areas where a successful Ponar sample was obtained. Samples were collected approximately 0.5 to 0.75 m elevation above the present water level. All sampling was performed directly above what appeared to be the regular bank-full condition. Table 4.2 notes the distance to water’s edge and describes the sample and associated vegetation community.

Table 4.2 Shovel Sampling

Sample ID

Distance from Water

(m)

Vegetation Community

Notes

Upper West 3 Black Spruce, Red Osier Dogwood

Boulders/cobble integrated in with soil

Upper East 2 Black Spruce, Horsetail, Golden Rod

Shallow soils, approx 30 cm to bedrock

Middle West 2 Sedges, Horsetail, Steep bank Middle East 1.5 Black Spruce, Red Osier

Dogwood Shallow soils, 30 cm to bedrock

Down West 1.5 Grasses and Sedges, Fallen Spruce

Steep bank

Down East 4 Sedges, Alders, Red Osier Dogwood

Gradual bank, back of bay, upstream from water gauge



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4.3 Laboratory Results In total, 14 samples were submitted to Hatch’s Niagara Falls geotechnical laboratory for organic percentage and grain size analysis. Table 4.3 illustrates both the total organic percentage and the grain size percentage. Grain size plots and the laboratory results can be found in Appendix A.

Table 4.3 Sample Analysis Summary

Sample ID Percent Organic Percentage of Material After Organic Removal % Fines % Sand % Gravel

Sed 1 2.23 6 94 Sed 2 2.39 9 90 1 Sed 3 30.99 78 22 Sed 4 5.14 99 1 Sed 5 3.06 98 2 Sed 6 12.76 94 6 Sed 7 10.44 59 41 Sed 8 5.09 93 7 Upper West 19.78 93 7 Upper East 4.92 96 4 Middle West 3.81 99 1 Middle East 6.64 94 6 Down West 2.98 90 6 4 Down East 5.20 97 3

5. Water Level Simulations 5.1 Methodology

The U.S. Army Corps of Engineers' River Analysis System (HEC-RAS) was used to perform water surface profile analysis for the study reach to evaluate the changes in water levels upstream of the plant. The HEC-RAS is a one-dimensional river hydraulics package. The model is capable of modeling water surface profiles for steady gradually varied flow. The system can handle a single river reach, a dendritic system, or a full network of channels. The model can simulate subcritical, supercritical and mixed flow regime water surface profiles.

The basic computational procedure is based on the solution of the one -dimensional energy equation. Energy losses are evaluated by friction (Manning's equation) and contraction/expansion (coefficient multiplied by the change in velocity head). The momentum equation is utilized in situations where the water surface profile is rapidly varied. These situations include mixed flow regime calculation (i.e., hydraulic jumps), hydraulics of bridges and evaluating profiles at river confluences (stream junctions).

The effects of various obstructions such as, culverts, weirs, spillways and other structures in the flood plain may be considered in the computations. The model is also used for assessing the change in



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water surface profiles due to changes on the flow control structures of a river or channel improvements.

Water surface levels are computed from one cross section to the next by solving the Energy equation with an iterative procedure called the standard step method. The Energy equation is written as follows:

Where:

Y1,Y2 = depth of water at cross sections

Z1, Z2 = elevation of the main channel inverts

V1,V2 = average flow velocities (total discharge/total flow area)

α1,α2 = velocity weighting coefficients

g = gravitational acceleration

he = energy head loss

The energy head loss (he) between two cross sections is comprised of friction losses and contraction or expansion losses. The equation for the energy head loss is as follows:

Where:

L = discharge weighted reach length

Sf = representative friction slope between two sections

C = expansion or contraction loss coefficient

The river reach roughness coefficient used in the model was based on field observations and the suggested range corresponding the river channel conditions in Open Channel Hydraulics (Chow, 1959). For the reach, the coefficient was taken as 0.035 for the main channel and 0.075 for the floodplain.

The water surface profile analysis provides some of the basic hydraulic parameters for sediment transport assessment (that will be discussed in the following sections).

5.2 Development of HEC RAS Geometry Model The geo-referenced cross sections were imported into a HEC RAS model. Nine surveyed sections were input in the 0.7 km reach. In areas where the river cross sections did not provide sufficient

Y ZVg

Y ZVg

he2 22 2

2

1 11 1

2

2 2+ + = + + +

α α

h LS CVg

Vge f= + −

α α2 22

1 12

2 2



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elevation, the sections were extended using the LiDAR mapping. Roughness coefficients of 0.035 and 0.075 were used for the channel and overbank areas, respectively. The roughness coefficients were derived from a calibrated HEC RAS run on a portion of Trout Lake River below Big Falls.

The water surface elevations coinciding with the proposed dam and spillway were used as the downstream boundary condition. A weir coefficient of 1.7 was used for the 64-m broad crested overflow spillway. The rating curve for the spillway is shown in Table 5.1.

Table 5.1 Rating Table for Overflow Spillway at Big Falls

*Flow over weir (assuming plant is shut down)

5.3 Simulation Scenarios The following scenarios were simulated:

Pre-development:

1. Summer low flow (mean of August): 16.8 m3/s

2. Rated turbine flow: 24.5 m3/s

3. 2-year flood flow: 42 m3/s


For pre-development modeling, the downstream boundary conditions used were critical depth due to the existence of the falls which will lead to critical at the end of the modeled reach.

Post-development:

1. Summer low flow (mean of August): 16.8 m3/s

2. Rated turbine flow: 24.5 m3/s



For the post-development simulations, the downstream boundary conditions used was the weir rating curve (Table 5.1) as the dam would be in place at that time.

The purpose of simulating the pre-development and post-development conditions for the same flow rate is to compare the water level and associated hydraulic parameters.

Total River Flow (m3/s)

Water Surface Elevation

(m) 24.5 368.77

34.0* 369.41 42.0* 369.47 60.0* 369.61

117.0* 369.94



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The study reach was represented by 20 cross sections. Nine of the cross sections were obtained based on field survey data. The surveyed data was entered into the HEC-RAS model. Eleven additional cross sections in the head pond are used in the model. These cross sections were obtained based on available topographical information of the study area. There are water level observations during the field survey undertaken by Trow in 2011. The edge of water was used as a guide to estimate the depth of water inside the river channel. T he bottom elevation of the river was then estimated.

5.4 Results The HEC-RAS model was run for both the pre-development and the post-development conditions for three flow rates as described in Section 5.2 and 5.3.

Table 5.2 summarize the simulation results for the Pre-development conditions. The results of post-development was presented in Table 5.3.

Table 5.2 Pre-Development Conditions Simulation Results

Cross Section

Bed EL

Q=16.8 m3/s Q = 24.5 m3/s Q = 34 m3/s Q = 42 m3/s Q = 60 m3/s Q = 117 m3/s Water

EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

1788 367.6 368.75 0.3 368.88 0.39 369.04 0.49 369.15 0.55 369.38 0.68 369.97 0.97 1743 368.2 368.57 1.74 368.65 1.97 368.75 2.2 368.82 2.35 368.97 2.64 369.37 3.29 1608 366.3 366.7 1.46 366.91 1.32 367.13 1.33 367.28 1.37 367.58 1.48 368.31 1.8 1434 365.2 366.53 0.66 366.73 0.82 366.93 1 367.07 1.11 367.35 1.36 368.02 1.96 1234 365.3 366.45 0.55 366.63 0.69 366.82 0.83 366.95 0.94 367.21 1.14 367.83 1.65 1029 365.7 366.25 1.04 366.39 1.18 366.54 1.34 366.64 1.45 366.85 1.69 367.34 2.27 942 365.25 366.14 0.71 366.26 0.9 366.39 1.11 366.48 1.25 366.65 1.55 367.04 2.32 877 365.6 365.89 1.51 365.95 1.72 366.03 1.93 366.08 2.06 366.2 2.32 366.5 2.89 792 364.8 365.18 0.55 365.3 0.6 365.43 0.65 365.53 0.68 365.74 0.75 366.31 0.89 727 363.74 365.15 0.42 365.25 0.54 365.38 0.66 365.48 0.74 365.68 0.88 366.23 1.18 671 362.18 365.13 0.5 365.22 0.7 365.33 0.93 365.4 1.09 365.56 1.45 365.92 2.39 600 363.34 365.13 0.32 365.22 0.43 365.32 0.56 365.4 0.64 365.56 0.81 365.97 1.23 538 360.64 365.13 0.07 365.22 0.1 365.33 0.13 365.41 0.16 365.58 0.21 366.02 0.37 476 361.7 365.13 0.08 365.22 0.11 365.33 0.15 365.41 0.18 365.58 0.24 366.02 0.41 362 362.04 365.13 0.14 365.22 0.2 365.33 0.27 365.4 0.31 365.57 0.42 365.99 0.69 230 361.42 365.13 0.12 365.22 0.17 365.33 0.22 365.4 0.26 365.56 0.35 365.98 0.58 141 360.11 365.13 0.07 365.22 0.1 365.33 0.13 365.4 0.15 365.56 0.21 365.98 0.36 82 361.53 365.13 0.11 365.22 0.15 365.32 0.2 365.4 0.24 365.56 0.33 365.97 0.55 20 361.53 365.13 0.11 365.22 0.15 365.32 0.2 365.4 0.24 365.55 0.33 365.96 0.55 0 364.8 365.01 1.44 365.07 1.63 365.14 1.82 365.19 1.94 365.29 2.19 365.56 2.71



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Table 5.3 Post-Development Conditions Simulation Results

Cross Section

Bed EL

Q=16.8 m3/s Q = 24.5 m3/s Q = 34 m3/s Q = 42 m3/s Q = 60 m3/s Q = 117 m3/s

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

Water EL (m)

Vel. (m/s)

1788 367.60 368.75 0.30 368.88 0.39 369.46 0.37 369.54 0.43 369.72 0.56 370.22 0.88 1743 368.20 368.62 1.47 368.69 1.81 369.41 0.93 369.47 1.08 369.62 1.38 369.99 2.1 1608 366.30 368.69 0.22 368.78 0.30 369.42 0.34 369.49 0.4 369.65 0.55 370.04 0.96 1434 365.20 368.68 0.22 368.78 0.32 369.42 0.37 369.48 0.45 369.63 0.62 369.99 1.1 1234 365.30 368.68 0.17 368.78 0.25 369.42 0.29 369.48 0.35 369.62 0.48 369.98 0.85 1029 365.70 368.68 0.18 368.77 0.25 369.41 0.29 369.47 0.35 369.61 0.47 369.95 0.85 942 365.25 368.68 0.17 368.77 0.24 369.41 0.28 369.47 0.34 369.61 0.47 369.94 0.85 877 365.60 368.68 0.11 368.77 0.16 369.41 0.19 369.47 0.22 369.61 0.31 369.95 0.55 792 364.80 368.68 0.05 368.77 0.07 369.41 0.08 369.47 0.1 369.62 0.14 369.96 0.25 727 363.74 368.68 0.07 368.77 0.10 369.41 0.12 369.47 0.14 369.62 0.19 369.96 0.35 671 362.18 368.68 0.14 368.77 0.20 369.41 0.24 369.47 0.29 369.61 0.41 369.94 0.74 600 363.34 368.68 0.07 368.77 0.10 369.41 0.12 369.47 0.15 369.61 0.2 369.95 0.37 538 360.64 368.68 0.03 368.77 0.04 369.41 0.06 369.47 0.07 369.61 0.1 369.95 0.18 476 361.70 368.68 0.03 368.77 0.05 369.41 0.06 369.47 0.07 369.61 0.1 369.95 0.18 362 362.04 368.68 0.05 368.77 0.07 369.41 0.09 369.47 0.1 369.61 0.15 369.95 0.27 230 361.42 368.68 0.04 368.77 0.05 369.41 0.07 369.47 0.08 369.61 0.11 369.95 0.21 141 360.11 368.68 0.03 368.77 0.04 369.41 0.05 369.47 0.06 369.61 0.09 369.95 0.17 82 361.53 368.68 0.04 368.77 0.06 369.41 0.07 369.47 0.09 369.61 0.12 369.94 0.23 20 361.53 368.68 0.04 368.77 0.06 369.41 0.07 369.47 0.09 369.61 0.12 369.94 0.23 0 364.80 368.68 0.07 368.77 0.10 369.41 0.12 369.47 0.14 369.61 0.19 369.94 0.35

Comparing Tables 5.2 and 5.3, it is evident that the major change is that the water level will be increased from natural flow conditions by the dam’s flow regulation. Because of the changes in water levels and volume in the upstream reservoir, flow velocities are significantly lower. The lower flow velocities lead to lower shear forces acting on the banks and bottom of the upstream river. Therefore, the erosion potential due to shear force is substantially reduced (this will be discussed in the following sediment and erosion sections).

The pre- and post-project water levels along the reach are shown in Figure 5.1, while the pre- and post-project flow velocities are compared in Figure 5.2.



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Figure 5.1 Water Level Comparisons Between Pre- and Post-Development Conditions

Figure 5.2 Flow Velocity Comparisons

358

360

362

364

366

368

370

372

0 500 1000 1500 2000

Wat

er L

evel

(m)

Distance (m)

Water Level Pre Q=16.8

Bed

Pre Q=24.5

Pre Q=42

Pre Q=117

Post Q=16.8

Post Q=24.5

Post Q=42

Post Q=117

0

0.5

1

1.5

2

2.5

3

3.5

0 500 1000 1500 2000

Vel

ocit

y (m

/s)

Distance (m)

Flow Velocity

Pre Q=16.8

Pre Q=24.5

Pre Q=42

Pre Q=117

Post Q=16.8

Post Q=24.5

Post Q=42

Post Q=117



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6. Erosion Assessment

The assessment of erosion potential in the upstream reach takes into account two different mechanisms: shoreline erosion/change due to wave actions, and the shear force induced erosion on the river’s shoreline due to flow velocity. Section 6.1 describes the methodology for assessing shoreline erosion potential. Section 6.2 presents the evaluation of shear force erosion using the HEC-RAS model.

6.1 Shoreline Erosion Assessment Methodology Shoreline erosion is mainly caused by wave action induced downcutting of the shoreline. The downcutting is related to shear stress generated by waves. Bonnefille (1992) and Sayah (2006) showed that the shear velocity generated by wave can be expressed as:

2.2sinh

/

Where is shear velocity (m/s), H is the wave height (m), T is the wave period (seconds), � is the kinematic viscosity of water, k is the wave number given by k = 2� /L, d is depth of water (m) and L is the wave length (m).

The shear stress is then:

Where � is the τ is the shear stress (N/m2, or kg/m2). Using the calculated wave shear force, the potential for erosion can be assessed by the comparison of the shear force induced by the wave and the bank material’s resistance to the shear forces. If the shear force is higher than the shoreline’s resistance, erosion will be expected. If however the shoreline’s resistance is higher, no erosion is expected.

It must be pointed out that the potential for shoreline erosion by wave action will stop when equilibrium conditions are reached; that is, when the profile of the shoreline reaches a balanced condition. At that point, active erosion will stop until some additional changes occur, which affect the balance between the erosion and resistance forces.

In the above noted assessment, the wave characteristics are calculated by standard wave estimation methods described by the coastal engineering manual (USACE, 2010).

The results of the assessment for wave induced shoreline erosion are presented in Section 9.

6.2 Sediment Transport Assessment Methodology One of the primary concerns in power plant operation is the physical changes in the river channel that occur following dam construction. Sediment transport following dam operation can cause bed aggradation in upstream reservoir and degradation in downstream channel, which in turn can result in significant environmental consequences and jeopardize fish habitat. Therefore, an assessment of sediment transport potential is needed.



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The sediment transport assessment aims at the estimation of the flow capacity to pick up the sediments stored behind the dam and the potential of water to transport the sediment into the downstream river reach.

Once a soil particle erodes, it becomes part of the flow and may be transported a few millimetres or hundreds of kilometres. The distance is dependent upon the sediment transport capacity of the flow. Factors controlling sediment transport capacity can be grouped into three categories: fluid properties, sediment characteristics and hydraulic parameters associated with the flow path. As a particle travels, it may be considered to be either bed load, suspended load or wash load. The classification can change as it travels depending on the fluid, sediment, and especially hydraulic conditions.

The new version of HEC-RAS (version 4.1) has added sediment transport capability which can be used to evaluate sediment erosion and transport.

6.3 Sediment Continuity HEC-RAS sediment routing routines solve the sediment continuity equation also known as the Exner equation:

( )x

Qt

B sp ∂

∂−=

∂∂

−ηλ1

Where:

B = channel width

η = channel elevation

λp = active layer porosity

t = time

x = distance

Qs = transported sediment load.

This equation simply states that the change of sediment volume in a control volume is equal to the difference between the inflowing and outflowing loads.

6.4 Computing Transport Capacity The right side of the continuity equation is the sediment gradient across the control volume comparing the sediment inflow with the sediment outflow. Sediment inflow is simply the sediment entering the control volume from the upstream control volume(s) and any local sources (lateral sediment inflows). The maximum amount of sediment that can leave the control volume, is a function of the amount of sediment that the water can move. This is referred to as the sediment transport capacity, and it is computed for each control volume for each bed mixing time step.

Acker and White (1973) sediment transport capacity equations were used in the simulation. The sediment mobility number Fgr is expressed as:



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n

si

si

n

gr

dDa

Vsgd

uF

−

−=

1

log32)1(

Where:

u = shear velocity

g = gravitational acceleration

dsi = mean particle size

s = specific gravity of sediment

V = average flow velocity

a = model coefficient

D = depth of water

n = model parameter.

In the model, sediment will be grouped by grain size, and therefore, the model requires sediment size distribution as an input parameter. The HEC-RAS model calculates the transport capacity for each grain size class. The actual transport capacity for a site will be the weighted transport capacity by the percentage of sediment as follows:

i

n

iic TT ∑

=

=1

β

Where:

Tc = total transport capacity

n = number of grain size classes

βi = is the percentage of the active layer composed of material in grain size class i

Ti = the transport potential computed for the material in grain size class i.

When the sediment capacity of a flow condition is higher than the actual sediment load the flow carries, erosion will occur. HEC-RAS follows the approach of the work of Parthenaides (1962) to calculate erosion. When the critical shear is exceeded, particle erosion begins as individual particle or flocs are removed, one at a time, at a rate that is approximately a linear function of shear. When the mass erosion shear is exceeded, the bed starts to erode in multi-particle chunks or clods. This process, referred to as mass erosion or mass wasting, occurs at a higher rate than particle erosion, and it can also be approximated with a linear function of the bed shear. The equation to calculate erosion rate is:



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−=

1

c

b

e

Mdtdm

ττ

Where:

m = mass of material in the water column

T = time

Τb = bed shear stress

Τc = critical shear stress for erosion

M = empirical erosion rate for particle scour.

When the sediment load in the water column is higher than the sediment transport capacity, deposition will occur. The temporal constraint on deposition is the limiter based on the simplest and most robust theory. There is a well established theory for how fast particles can drop out of the water column and deposit fall velocity. By comparing the vertical distance, a particle has to travel to reach the bed surface and the vertical distance a particle travels in a time step, HEC-RAS will determine what percentage of the sediment surplus can actually deposit in a given control volume in a given time step. A deposition efficiency coefficient is calculated for each grain class (i):

)()(iD

tiVCe

sd

∆=

Where:

Cd = the deposition efficiency coefficient

Vs(i) = the fall velocity for grain size class i

∆t = the time step, and

De(i) = the effective depth of the water column over grain class i is transported.

Once the surplus or deficit in sediment rate is determined, a final deposition or erosion mass is computed. This mass is added to or subtracted from the control column by changing the cross section station/elevation points. The mass is converted into a volume and this change in volume is effectively spread over an upstream and downstream wedge which allows the height of the wedge to be computed.

6.5 Grain Size Distribution Sediment sampling of the Trout Lake River was taken at three locations within the 0.7 km reach. The location of the sampling points is shown in Figure 4.1. The grain size distribution for each sample is shown in Appendix A.



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6.6 Results of HEC-RAS Erosion Simulations The river reach was analyzed for sediment transport during the 2-yr flood. It was assumed that during the flood, 24 m3/s would be directed through the plant turbine and bypass structure. The remaining flow would pass over the uncontrolled spillway.

The peak water surface elevation during the event was 370.86 m over the entire study reach. Velocities ranged from a low of 0.05 m/s at Sections 2 and 3 to a high of 0.11 m/s at Section 8 during the peak discharge. These velocities are quite low because the dam causes the flow cross section to be very wide.

The results for the 2-yr flood event showed almost no change to the cross sections for either of the transport functions. The Yang transport function showed that the bed invert increased by less than 0.001 m at Section 6. The invert at the remaining sections were unchanged. There was no change to the cross section invert elevations when the Ackers and White function was used.

6.7 Results of Shoreline Erosion Assessment The wave characteristics are calculated for different design event up to the 1:100-yr waves. The wave characteristics are calculated using the wind speed provided by Ontario Building Code (2006) for Kenora area.

The study reach is narrow ( about 100 m wide) and the water is shallow (about 7 m deep in the reservoir). The river is not straight and the maximum distance for wind fetch is about 300 m. Therefore the wind waves generated are small. The 1:100-yr wave height is about 0.25 m. The corresponding wave induced shear stress is about 0.06 N/m2, which is quite low. The shoreline material would not have significant erosion because of the low eroding force. Grain sizes distribution show for the upstream area were surveyed and presented in Appendix A (Samples 1, 2 and 3). The samples shown that the banks consist of significant amount of clay which increases the erosion resistance (the critical shear stress is about 3 to 7 N/m2 >0.6 N/ m2 at the site).

It shall be pointed out that there will be some erosion around the shoreline occurring during the initial fill up period due to the higher water level which leads to the wetting of the dry banks and weaken the soil resistance. During the initial period, the loosing soils at weak spots will be eroded. This erosion activities will not last for long time. The banks will stabilize and the bank profile will reach equilibrium conditions.

It is concluded that the shoreline erosion will not be a significant problem in the long term operation.

6.8 Sediment Transport Analysis The sediment transport module with the HEC RAS model was used to determine the impact that the 2-yr flood has at each cross section. A lognormal fit to the maximum flow data at the Trout Lake River gauge at Big Falls resulted in the peak discharges shown in Table 6.1. The 2-yr flood peak is 42 m3/s.

The 2-yr flood was chosen for the sediment transport simulation because 2-yr flood has been considered as the ‘channel forming’ discharge by geo-morphologists meaning that it is related to erosion activities for natural rivers.



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Table 6.1 Estimated Peak Discharge for Trout Lake River at Big Falls

The input hydrograph for the HEC RAS quasi unsteady flow was determined by researching the daily hydrographs for the Water Survey of Canada gauge Trout Lake River Above Big Falls (05QC003) at Big Falls. A storm from May 30, 2010 to June 23, 2010, seemed like a single-storm event. The hydrograph for this event is shown in Figure 6.1. The peak discharge for this event was about 53 m3/s. The hydrograph was adjusted to the peak discharge (42 m3/s) for the 2-yr event.

The sediment transport analysis was set up to run for both the Ackers and White and the Yang transport functions. The Exner 5 sorting method and the Ruby fall velocity method was specified. The upstream boundary condition at Section 9 was set to the equilibrium load. The maximum erosion depth was limited to 1.5 m across the entire length of the section.

Return Period (yrs)

Peak Discharge (m3/s)

2 42 5 60 10 73 20 86



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Figure 6.1 Hydrograph for Trout Lake River Above Big Falls

FIGURE 6.1 0

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5/26/2010 5/31/2010 6/5/2010 6/10/2010 6/15/2010 6/20/2010 6/25/2010

Dis

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ms)

HYDROGRAPH FOR TROUT LAKE RIVER ABOVE BIG FALLS

Actual Event



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7. Reservoir Sedimentation Assessment To evaluate the potential of the reservoir sedimentation due to the construction of the dam, the HEC-RAS model was run for the design flow conditions under various flow rates. The flow rates examined include the 1.5-yr (34.4 m3/s) flow, the 2-yr flow (42.0 m3/s) and the 5-yr flood (60.0 m3/s). The resulting shear stress corresponding to these flow rates are summarized in Table 7.1.

Table 7.1 Shear Stresses Comparison

Cross Section

Shear Stress (Pa)

Q=34.4 m3/s Q=42.0 m3/s Q=60.0 m3/s

Pre- Post Pre- Post- Pre- Post- 1788 2.53 1.32 3.13 1.77 4.49 2.87 1743 72.41 9.4 78.68 12.35 91.12 19.09 1608 22.44 0.82 22.28 1.16 23.32 2.09 1434 9.8 0.79 11.77 1.12 16.26 2.05 1234 7.03 0.49 8.49 0.71 11.8 1.3 1029 22.45 0.49 25.18 0.7 31.37 1.26 942 13.92 0.47 17.17 0.68 24.9 1.25 877 61.6 0.21 67.23 0.31 78.81 0.56 792 5.87 0.04 6.15 0.06 6.75 0.12 727 5.32 0.07 6.46 0.11 7.47 0.2 671 8.52 0.25 11.72 0.35 17.72 0.68 600 3.48 0.08 4.49 0.11 6.85 0.22 538 0.13 0.02 0.18 0.02 0.33 0.05 476 0.21 0.02 0.29 0.03 0.5 0.05 362 0.65 0.04 0.89 0.05 1.51 0.1 230 0.36 0.02 0.47 0.03 0.78 0.05 141 0.14 0.01 0.19 0.02 0.34 0.04 82 0.35 0.03 0.48 0.04 0.83 0.07 20 0.35 0.03 0.48 0.04 0.83 0.08 0 57.22 0.1 62.42 0.15 73.5 0.28

Maa et. al. (2008) conducted a sediment deposition study for very fine material and they concluded that the critical deposition shear stress for suspended fine sediment is approximately 0.042 Pa. Using their results, it can be seen from Table 7.1 that the shear stress for the rated flow will be lower than the critical deposition shear stress near the dam (except for the two most upstream cross sections. It means that deposition of suspended will occur in the head pond at locations near the dam for the rated flow. For the 2-yr flood, the deposition zone is smaller, but deposition will occur in the area near the dam. For the 5-yr flood, it is evident that the suspended sediment deposition will only occur at a few locations but no deposition will occur for the majority of the reach.



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It is concluded from the above analysis that reservoir deposition of suspended sediment will occur under normal flow and moderate flood conditions. When a significant flood (equal to or higher than the 5-yr flood) occur, the suspended sediment will be carried downstream.

8. Summary It is concluded based on the above assessment that:

1. The construction of the dam will lead to changes on both the hydraulic conditions and the sediment transport process on the upstream head-pond area. The flow velocities will become much lower than pre-developed conditions and the depth of water will be significantly increased. As a result of these changes, sediment carrying capacity of the flow will become smaller.

a) The HEC-RAS model simulations show that the depth of water under typical flow conditions (e.g., rated turbine flow) changes from about 1 m to more than 9 m deep in the head-pond area. This leads to a significant reduction in flow velocity(an order of magnitude slower).

b) The shear stress reductions in the head-pond area are more significant. Under normal flow conditions, the fine sediment in suspension will be deposited in the reservoir. Only during high flows (i.e. >2-yr flood) will the fine sediment be carried downstream.

2. Some erosion of the shoreline will occur during the initial reservoir fill and operating period due to wetting of the bank soils and changes in water levels. Measures to maintain soil stability along the new edge of water include retaining woody vegetation root systems and shrubs. After the initial shoreline erosion period, the process will be stabilized since the potential for wave generated shear stress within the head-pond area is small, in combination with natural regeneration of shoreline vegetation (herbaceous and woody shrubs). In conclusion, erosion of shorelines will not be a long-term problem.

The proposed run-of-river operational regime for the facility will result in some fluctuations of head-pond water level (mostly upward) in response to larger hydrologic events, but no rapid fluctuation of water levels is anticipated. These changes in water levels in the head pond will be in response to seasonal and episodic natural events, and are unlikely to result in significant erosion of the shoreline within the head ponds.

It is recommended that a sediment monitoring program be established to evaluate the long-term variations of the sediment movement.



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9. References: Bonnefille, R., 1992, Cours d’ hydraulique maritime, 3éme edn, Masson

Maa, J. P-Y, Kwon, J. Hwang, K-N and Ha, H-K, 2008, Critical Bed Shear Stress for Cohesive Sediment Deposition Under Stead Flows, Journal of Hydrologic Engineering, ASCE December, 2008

Sayah, S., 2006, Efficiency of brushwood fences in shore protection against wind-wave induced erosion, Thesis, PRÉSENTÉE à LA FACULTÉ ENVIRONNEMENT NATUREL, ARCHITECTURAL ET CONSTRUIT, Institut des infrastructures, des ressources et de l'environnement

USACE, 2010, Coastal Engineering Manual, U. S. Army Corps of Engineers

USACE, 2008, HEC-RAS River Analysis System Hydraulic Reference Manual, U. S. Army Corps of Engineers, Hydrologic Engineering Center



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Appendix A

Head Pond Sediment/Soil Collections

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#60

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#16

UPPER PP EAST 0 4 96


1.00

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H327203.201.03, Rev. 0

© Hatch 2012/04

Appendix B HEC RAS Cross Sections

B-1

Appendix B HEC RAS Cross Sections

HEC-RAS Cross Sections (listed from Upstream to Downstream) are plotted in the following figures.

Figure B.1 The Upstream End Cross Section

Figure B.2 The Section Cross Section

100 120 140 160 180 200 220366

368

370

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Trout Lake River-withHydraulics P lan: PostydraulicsA 3/ 26/2012

River = TROUT LAKE RIVER Reach = UPPER RS = 18 Water Levels along the River

Station (m)

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n (m

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WS 100 Yr Prop

WS 100 Yr Exst

WS 5 Yr Prop

WS 2 Yr Prop

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WS 2 Yr Exst

WS 1.5 Yr Exst

WS Rated Exst

WS Rated Prop

WS Feb 2011

WS LF Prop

WS LF Exst

WS Nov 2011

Ground

Bank Sta

.075 .035 .075

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WS Rated Prop

WS Rated Exst

WS LF Prop

WS Feb 2011

WS LF Exst

WS Nov 2011

Ground

Bank Sta

.075 .035 .075

B-2

Figure B.3 The Third Cross Section

Figure B.4 The Fourth Cross Section

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Ground

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WS 1.5 Yr Exst

WS Rated Exst

WS Feb 2011

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Ground

Bank Sta

.075 .035 .075

B-3

Figure B.5 The Fifth Cross Section

Figure B.6 The Sixth Cross Section

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WS Feb 2011

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Ground

Bank Sta

.075 .035 .075

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WS 5 Yr Exst

WS 2 Yr Exst

WS 1.5 Yr Exst

WS Rated Exst

WS Feb 2011

WS LF Exst

WS Nov 2011

Ground

Bank Sta

.075 .035 .075

B-4

Figure B.7 The Seventh Cross Section

Figure B.8 The Eighth Cross Section

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WS 5 Yr Exst

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WS Feb 2011

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WS Nov 2011

Ground

Bank Sta

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WS 5 Yr Exst

WS 2 Yr Exst

WS 1.5 Yr Exst

WS Rated Exst

WS Feb 2011

WS LF Exst

WS Nov 2011

Ground

Bank Sta

.075 .035 .075

B-5

Figure B.9 The Ninth Cross Section

Figure B.10 The Tenth Cross Section

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WS 100 Yr Exst

WS 5 Yr Exst

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WS 1.5 Yr Exst

WS Rated Exst

WS Feb 2011

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WS Nov 2011

Ground

Bank Sta

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WS 5 Yr Exst

WS 2 Yr Exst

WS 1.5 Yr Exst

WS Rated Exst

WS Feb 2011

WS LF Exst

WS Nov 2011

Ground

Bank Sta

.075 .035 .075

B-6

Figure B.11 The Eleventh Cross Section

Figure B.12 The Twelfth Cross Section

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WS 5 Yr Exst

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WS Rated Exst

WS Feb 2011

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Ground

Bank Sta

.075 .035 .075

B-7

Figure B.13 The Thirteenth Cross Section

Figure B.14 The Fourteenth Cross Section

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WS Feb 2011

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Ground

Bank Sta

.075 .035 .075

B-8

Figure B.15 The Fifteenth Cross Section

Figure B.16 The Sixteenth Cross Section

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B-9

Figure B.17 The Seventeenth Cross Section

Figure B.18 The Eighteenth Cross Section

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B-10

Figure 19 The Nineteenth Cross Section

Figure B.20 The Last Cross Section (at the dam)

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Trout Lake River-withHydraulics P lan: PostydraulicsA 3/ 26/2012 River = TROUT LAKE RIVER Reach = UPPER RS = .1 20 meters upstream of centerline of dam Water Levels along the River

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River = TROUT LAKE RIVER Reach = UPPER RS = .01 Water Levels along the River

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.035

Horizon Hydro Inc.

Calibration of the HEC-RAS Model


327203.201.18 Rev. 0

March 5, 2013

Horizon Hydro Inc. - Trout Lake River Hydro Project Calibration of the HEC RAS Model

H327203.201.18, Rev. 0 Page 1

© Hatch 2013 All rights reserved, including all rights relating to the use of this document or its contents.

Project Report

March 5, 2013 Horizon Hydro Inc.



H327203.201.18, Rev. 0 Page 2


Calibration of the HEC RAS Model

Table of Contents

1. Introduction ........................................................................................................................................... 3

2. Development of the HEC RAS Geometry Model ................................................................................ 3

3. Calibration ............................................................................................................................................. 3

3.1 Approach ....................................................................................................................................... 3 3.2 Methodology ................................................................................................................................. 4 3.3 Results for Feb 2011 .................................................................................................................... 4 3.4 Results for November 2011 .......................................................................................................... 5

4. Simulated Flow Scenarios ................................................................................................................... 5

4.1 Existing Conditions ....................................................................................................................... 5 4.2 Post-Project .................................................................................................................................. 6

5. Summary of Results ............................................................................................................................. 6

List of Tables Table 1 February 2011 Calibration ............................................................................................................ 4Table 2 November 2011 Calibration .......................................................................................................... 5Table 3 Discharges .................................................................................................................................... 5 List of Figures Figure 1 Schematic of HEC RAS Cross Section Locations Appendix A Existing Conditions Table 4 Existing Conditions, Low Flow Discharge of 16.8 cms Table 5 Existing Conditions, Plant Flow Discharge of 24.5 cms Table 6 Existing Conditions, 1.5 year Flood Discharge of 34.45 cms Table 7 Existing Conditions, 2 year Flood Discharge of 42 cms Table 8 Existing Conditions, 5 year Flood Discharge of 60 cms Table 9 Existing Conditions, 100 year Flood Discharge of 117 cms Appendix B Post Project Conditions Table 10 Post Project, Low Flow Discharge of 16.8 cms Table 11 Post Project, Plant Flow Discharge of 24.5 cms Table 12 Post Project, 1.5 year Flood Discharge of 34.45 cms Table 13 Post Project, 2 year Flood Discharge of 42 cms Table 14 Post Project, 5 year Flood Discharge of 60 cms Table 15 Post Project, 100 year Flood Discharge of 117 cms Appendix C Photographs


H327203.201.18, Rev. 0 Page 3


1. Introduction The proposed Trout Lake River Hydro site is situated on the Canadian Shield along Trout Lake River and downstream of Trout Lake and Little Trout Lake. The dam for the hydro site is situated upstream of Big Falls.

A one-dimensional hydraulic model of the Trout Lake River in the vicinity of the proposed development was used to assess pre- and post development impacts on water surface elevation and average sectional velocity. This report documents and presents the calibration procedure and sensitivity tests conducted to validate the model.

A general description of the project can be found in the Feasibility Report for the Trout Lake River Hydro Project (H327203.201.06)

2. Development of the HEC RAS Geometry Model Nine geo-referenced cross sections were surveyed between February 15 and February 18 of 2011. Water surface elevations at the cross section were recorded during the survey. The cross sections were used to create a one-dimensional numerical model within the HEC RAS software tool. The cross sections were within 0.7 stream kilometres of the proposed dam. In areas where the river cross sections did not provide sufficient overbank detail, the sections were extended using topographic data collected via LiDAR techniques. See Figure 1 for a schematic of the cross-section locations along the river. Aerial photos of the river are shown in Appendix C.

The model was extended an additional 1.1 km upstream of the nine sections using LiDAR mapping. The LiDAR mapping was used for the geometry of the overbank areas. The channel bottom was estimated and based on aerial photography and an iterative desktop procedure involving adjustment of the channel bottom (with an assumed Manning’s roughness coefficient) to match simulated to recorded water levels (see next section for details). The channel bottom was not field surveyed due to safety concerns.

3. Calibration 3.1 Approach

The one-dimensional numerical model was used to compute and compare water surface elevations for pre- and post-project conditions. Where channel bathymetry was available, the channel roughness was calibrated to a measured flow and water surface elevation (February 2011). In areas where no bathymetry was available, a reasonable channel roughness was assumed and the channel bathymetry was adjusted so the calculated water surface elevation would agree with the measured flow and water surface elevation (November 2011).

In the river reach where no bathymetry was available, the model was calibrated to three channel roughness values by adjusting the channel bathymetry. Roughness values of


H327203.201.18, Rev. 0 Page 4


0.03, 0.035 and 0.04 were selected in order to test the sensitivity of the channel geometry and channel roughness during post-project conditions.

3.2 Methodology The portion of the stream from location of the proposed dam to a point 0.7 km upstream was calibrated to the surveyed water surface elevations of February 2011. A discharge of about 18 m3/s was measured at a nearby gauge. Channel roughness coefficients were adjusted in order to meet the measured water surface elevations of February 2011. The overbank roughness was estimated at 0.07. A channel roughness of 0.035 provided a fair match to the measured water levels.

A second set of water surface elevations was acquired November 17, 2011 from a point 0.7 km from the proposed dam to a point 1.1 km upstream of the initial point. A flow of 8.2 m3/s was measured at the nearby gauge.

Since the channel bottom geometry and the roughness for the upstream sections were not known, a channel roughness coefficient was selected and the channel bottom elevation was adjusted until the modeled water surface elevation (WSEL) closely matched the measured WSEL recorded on November 17, 2011.

A channel roughness of 0.035 was initially selected as this value matched the calibrated channel coefficient for the lower portion of Trout Lake River (proposed dam to Section 9). Another model of a section of the Trout Lake River below Big Falls had also been calibrated to a channel roughness of 0.035.

3.3 Results for Feb 2011 The river reach from the proposed dam to a point 0.7 km upstream was calibrated to the February 2011 WSEL. A comparison of the modeled water surface elevations to the observed elevation are given in Table 1. A roughness coefficient of 0.035 was used in the calibration.

Table 1 February 2011 Calibration

Section

Observed WSEL

(m)

HEC RAS WSEL

(m)

Difference

(m) 0.01 365.02 0.1 365.14 1 365.06 365.14 0.08 2 365.11 365.14 0.03 3 365.12 365.14 0.02 4 365.12 365.14 0.02 5 365.17 365.14 -0.03 6 365.24 365.15 -0.09 7 365.29 365.14 -0.15 8 365.48 365.15 -0.33 9 365.50 365.16 -0.34


H327203.201.18, Rev. 0 Page 5


3.4 Results for November 2011 The river reach from a point 0.7 km upstream of the proposed dam to the end of the study reach was calibrated to the November 2011 WSEL. A comparison of the modeled water surface elevations to the observed elevations are given in Table 2.

Table 2 November 2011 Calibration

Section

Observed WSEL

(m)

Roughness n=0.03

Roughness n=0.035

Roughness n=0.043

HEC RAS WSEL

(m)

Diff. (m)

HEC RAS WSEL

(m)

Diff. (m)

HEC RAS WSEL

(m)

Diff. (m)

10 364.96 365.02 0.06 365.03 0.07 365.03 0.07 11 365.80 365.80 0.0 365.80 0.00 365.80 0.0 12 365.92 365.93 0.01 365.96 0.04 365.97 0.05 13 366.06 366.06 0.0 366.03 -0.03 366.06 0.0 14 366.15 366.19 0.04 366.13 -0.02 366.19 0.04 15 366.18 366.23 0.05 366.19 0.01 366.23 0.05 16 366.55 366.53 -0.02 366.53 -0.02 366.53 -0.02 17 368.51 368.49 -0.02 368.49 -0.02 368.53 0.02 18 368.51 368.60 0.09 368.57 0.06 368.59 0.08

4. Simulated Flow Scenarios 4.1 Existing Conditions

Pre-development water surface elevations were estimated for six flows. The flows are listed in Table 3.

Table 3 Discharges

Event Discharge (m3/s)

Low Flow 16.8 Turbine Rated 24.5 1.5 Yr 34.4 2 Yr 42 5 Yr 60 100 Yr 117

The water surface elevations for the above discharges are given in Appendix A (Tables 4 through 9). Each table shows the water surface elevations for the three roughness coefficients. The variation in the roughness coefficients only pertains to Sections 10 through 18.

Differences in the water surface elevation at each section were noted for the three roughness coefficients. A maximum difference of 0.10 m occurred for the low flow discharge at Section 13. The difference generally increased as the discharge increased. A maximum difference of 0.26 m occurred at Section 13 for the 100-yr event.


H327203.201.18, Rev. 0 Page 6


4.2 Post-Project Post-project water levels were run for the same six flows. The water surface elevations are given in Appendix B (Tables 10 through 15). Each table shows the water surface elevations for the three roughness coefficients.

The water surface profiles show that most of the sections are in the backwater of the proposed dam. Section 16 at a discharge of 16.8 m3/s shows the water levels are essentially the same for the three channel roughness values. Similar results were found for the other five flows.

5. Summary of Results The following results were determined from the analysis.

1. The lower reach of Trout Lake River (Sections 1 through 9) was calibrated to the February 2011 discharge. A channel roughness of 0.035 was determined.

2. The upper reach of Trout Lake River was calibrated to the November 2011 water levels for three different roughness values by adjusting the channel section bathymetry for each roughness. This exercise resulted in three channel geometries for the upper reach of the river.

3. At a given flow in the pre-development condition, the model showed that differences in the water levels resulted from the three channel geometries. The maximum difference in water level at a cross section was 0.10 m (Section 13) at a low flow discharge of 16.8 m3/s and 0.26 m (Section 13) at the 100-yr discharge of 117 m3/s.

4. At a given flow in post-project conditions, the model showed that there was very little difference in the water levels at a cross section from the proposed dam to Section 16 for the three channel geometries. Upstream of Section 16, the maximum difference in water level was 0.10 (Section 18) m at a discharge of 16.8 m3/s and 0.10 m (Section 17) at a discharge of 117 m3/s.

5. Water surface elevations were determined for post project conditions for six discharges. Almost no variation in the water surface elevations for the three roughness coefficients were found at each section for a given discharge. Since most of the modeled reach of the river is in the backwater of the proposed dam, these results can be expected

:


H327203.201.18, Rev. 0 Page 7


Figures


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Figure 1 – Schematic of Model Cross Section Locations


H327203.201.18, Rev. 0 Page 9


APPENDIX A EXISTING CONDITIONS


H327203.201.18, Rev. 0 Page 10


Table 4 – Existing Conditions, Low Flow Discharge of 16.8 cms

Section

Water Surface Elevations for Low Flow Discharge of 16.8 cms

Geometry for n = 0.03



0.01 365.01 365.01 365.01 0.1 365.13 365.13 365.13 1 365.13 365.13 365.13 2 365.13 365.13 365.13 3 365.13 365.13 365.13 4 365.13 365.13 365.13 5 365.13 365.13 365.13 6 365.13 365.13 365.13 7 365.13 365.13 365.13 8 365.13 365.13 365.13 9 365.15 365.15 365.15 10 365.18 365.18 365.18 11 365.89 365.89 365.89 12 366.10 366.14 366.15 13 366.18 366.25 366.28 14 366.39 366.39 366.43 15 366.47 366.49 366.50 16 366.65 366.68 366.65 17 368.61 368.58 368.66 18 368.78 368.75 368.77


H327203.201.18, Rev. 0 Page 11


Table 5 – Existing Conditions, Plant Flow Discharge of 24.5 cms

Section

Water Surface Elevations for Plant Flow Discharge of 24.5 cms




0.01 365.07 365.07 365.07 0.1 365.22 365.22 365.22 1 365.22 365.22 365.22 2 365.22 365.22 365.22 3 365.22 365.22 365.22 4 365.22 365.22 365.22 5 365.22 365.22 365.22 6 365.22 365.22 365.22 7 365.22 365.22 365.22 8 365.22 365.22 365.22 9 365.25 365.25 365.25 10 365.29 365.30 365.30 11 365.95 365.95 365.95 12 366.21 366.26 366.28 13 366.30 366.39 366.44 14 366.54 366.58 366.62 15 366.65 366.68 366.70 16 366.81 366.89 366.86 17 368.69 368.65 368.65 18 368.92 368.88 368.89


H327203.201.18, Rev. 0 Page 12


Table 6 – Existing Conditions, 1.5 year Flood Discharge of 34.45 cms

Section

Water Surface Elevations for 1.5 Year Flood Discharge of 34.4 cms




0.01 365.14 365.14 365.14 0.1 365.32 365.32 365.32 1 365.32 365.32 365.32 2 365.33 365.33 365.33 3 365.33 365.33 365.33 4 365.33 365.33 365.33 5 365.33 365.33 365.33 6 365.33 365.33 365.33 7 365.32 365.32 365.32 8 365.33 365.33 365.33 9 365.38 365.38 365.38 10 365.43 365.43 365.43 11 366.03 366.03 366.03 12 366.34 366.39 366.42 13 366.44 366.54 366.60 14 366.71 366.77 366.82 15 366.84 366.90 366.92 16 367.02 367.11 367.10 17 368.79 368.75 368.75 18 369.07 369.04 369.05


H327203.201.18, Rev. 0 Page 13


Table 7 – Existing Conditions, 2 year Flood Discharge of 42 cms

Section

Water Surface Elevations for 2 Year Flood Discharge of 42 cms




0.01 365.19 365.19 365.19 0.1 365.40 365.40 365.40 1 365.40 365.40 365.40 2 365.40 365.40 365.40 3 365.40 365.40 365.40 4 365.40 365.40 365.40 5 365.41 365.41 365.41 6 365.41 365.41 365.41 7 365.40 365.40 365.40 8 365.40 365.40 365.40 9 365.48 365.48 365.48 10 365.52 365.53 365.53 11 366.08 366.08 366.08 12 366.42 366.48 366.51 13 366.54 366.64 366.71 14 366.83 366.89 366.95 15 366.97 367.03 367.07 16 367.16 367.26 367.26 17 368.86 368.82 368.82 18 369.18 369.15 369.16


H327203.201.18, Rev. 0 Page 14



Section





0.01 365.29 365.29 365.29 0.1 365.55 365.55 365.55 1 365.56 365.56 365.56 2 365.56 365.56 365.56 3 365.56 365.56 365.56 4 365.57 365.57 365.57 5 365.58 365.58 365.58 6 365.58 365.58 365.58 7 365.56 365.56 365.56 8 365.56 365.56 365.56 9 365.68 365.68 365.68 10 365.73 365.74 365.74 11 366.20 366.20 366.20 12 366.58 366.65 366.70 13 366.73 366.85 366.93 14 367.08 367.15 367.22 15 367.23 367.32 367.37 16 367.44 367.55 367.58 17 369.01 368.97 368.97 18 369.41 369.38 369.39


H327203.201.18, Rev. 0 Page 15



Section Water Surface Elevations for 100 Year Flood Discharge of 117 cms




0.01 365.56 365.56 365.56 0.1 365.96 365.96 365.96 1 365.97 365.97 365.97 2 365.98 365.98 365.98 3 365.98 365.98 365.98 4 365.99 365.99 365.99 5 366.02 366.02 366.02 6 366.02 366.02 366.02 7 365.97 365.97 365.97 8 365.92 365.92 365.92 9 366.23 366.23 366.23 10 366.30 366.31 366.31 11 366.50 366.50 366.50 12 366.94 367.04 367.13 13 367.18 367.34 367.44 14 367.66 367.76 367.86 15 367.86 367.97 368.07 16 368.13 368.28 368.34 17 369.41 369.37 369.37 18 370.00 369.97 369.98


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APPENDIX B POST PROJECT CONDITIONS


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Table 10 – Post Project, Low Flow Discharge of 16.8 cms

Section

Water Surface Elevations for Low Flow Discharge of 16.8 cms




0.01 368.68 368.68 368.68 0.1 368.68 368.68 368.68 1 368.68 368.68 368.68 2 368.68 368.68 368.68 3 368.68 368.68 368.68 4 368.68 368.68 368.68 5 368.68 368.68 368.68 6 368.68 368.68 368.68 7 368.68 368.68 368.68 8 368.68 368.68 368.68 9 368.68 368.68 368.68 10 368.68 368.68 368.68 11 368.68 368.68 368.68 12 368.68 368.68 368.68 13 368.68 368.68 368.68 14 368.68 368.68 368.68 15 368.68 368.68 368.68 16 368.68 368.69 368.68 17 368.61 368.62 368.68 18 368.78 368.75 368.68


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Table 11 – Post Project, Plant Flow Discharge of 24.5 cms

Section

Water Surface Elevations for Plant Flow Discharge of 24.5 cms




0.01 368.77 368.77 368.77 0.1 368.77 368.77 368.77 1 368.77 368.77 368.77 2 368.77 368.77 368.77 3 368.77 368.77 368.77 4 368.77 368.77 368.77 5 368.77 368.77 368.77 6 368.77 368.77 368.77 7 368.77 368.77 368.77 8 368.77 368.77 368.77 9 368.77 368.77 368.77 10 368.77 368.77 368.77 11 368.77 368.77 368.77 12 368.77 368.77 368.77 13 368.77 368.77 368.77 14 368.77 368.77 368.78 15 368.78 368.78 368.78 16 368.78 368.78 368.78 17 368.69 368.69 368.70 18 368.92 368.88 368.89


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Table 12 – Post Project, 1.5 year Flood Discharge of 34.45 cms

Section

Water Surface Elevations for 1.5 Year Flood Discharge of 34.4 cms




0.01 369.36 369.36 369.36 0.1 369.36 369.36 369.36 1 369.36 369.36 369.36 2 369.36 369.36 369.36 3 369.36 369.36 369.36 4 369.36 369.36 369.36 5 369.36 369.36 369.36 6 369.36 369.36 369.36 7 369.36 369.36 369.36 8 369.36 369.36 369.36 9 369.36 369.36 369.36 10 369.36 369.36 369.36 11 369.36 369.36 369.36 12 369.36 369.36 369.36 13 369.36 369.36 369.36 14 369.36 369.37 369.37 15 369.37 369.37 369.37 16 369.37 369.37 369.38 17 369.35 369.36 369.36 18 369.41 369.41 369.42


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Table 13 - Post Project, 2 year Flood Discharge of 42 cms

Section





0.01 369.43 369.43 369.43 0.1 369.43 369.43 369.43 1 369.43 369.43 369.43 2 369.43 369.43 369.43 3 369.43 369.43 369.43 4 369.43 369.43 369.43 5 369.43 369.43 369.43 6 369.43 369.43 369.43 7 369.43 369.43 369.43 8 369.43 369.43 369.43 9 369.43 369.43 369.43 10 369.43 369.43 369.43 11 369.43 369.43 369.43 12 369.43 369.43 369.43 13 369.43 369.43 369.43 14 369.44 369.44 369.44 15 369.44 369.44 369.44 16 369.45 369.45 369.45 17 369.42 369.43 369.44 18 369.49 369.50 369.51


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Table 14 – Post Project, 5 year Flood Discharge of 60 cms

Section





0.01 369.59 369.59 369.59 0.1 369.59 369.59 369.59 1 369.59 369.59 369.59 2 369.59 369.59 369.59 3 369.59 369.59 369.59 4 369.59 369.59 369.59 5 369.59 369.59 369.59 6 369.59 369.59 369.59 7 369.59 369.59 369.59 8 369.59 369.59 369.59 9 369.60 369.60 369.60 10 369.60 369.60 369.60 11 369.59 369.59 369.59 12 369.59 369.59 369.59 13 369.59 369.60 369.60 14 369.60 369.60 369.61 15 369.60 369.61 369.62 16 369.62 369.63 369.63 17 369.57 369.60 369.61 18 369.69 369.70 369.72


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Table 15 – Post Project, 100 year Flood Discharge of 117 cms

Section





0.01 369.97 369.97 369.97 0.1 369.97 369.97 369.97 1 369.97 369.97 369.97 2 369.98 369.98 369.98 3 369.98 369.98 369.98 4 369.98 369.98 369.98 5 369.98 369.98 369.98 6 369.98 369.98 369.98 7 369.97 369.97 369.97 8 369.97 369.97 369.97 9 369.99 369.99 369.99 10 369.99 369.99 369.99 11 369.98 369.98 369.98 12 369.97 369.97 369.98 13 369.98 369.98 369.99 14 370.00 370.01 370.02 15 370.01 370.02 370.04 16 370.05 370.07 370.09 17 369.96 370.02 370.06 18 370.20 370.24 370.27


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APPENDIX C PHOTOGRAPHS


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Trout Lake River between Sections 5 and 14. The flow is from right to left.

8

9

10

11

12

13

14 5


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Looking Upstream at Sections 16 Through 18. Section 16 is at the base of the rapids

and Section 17 is at the upstream end of the rapids

Suite 500, 4342 Queen Street Niagara Falls, Ontario, Canada L2E 7J7 Tel 905 374 5200 Fax 905 374 1157

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