representative photographs - new hampshire · 19\appendices\appendices.docx a-8 appendix a –...
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J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-1 Appendix A – Representative Photographs
Appendix A
Representative Photographs
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-2 Appendix A – Representative Photographs
Suncook River – Old Primary Channel
Looking upstream at cross-section 1
Looking downstream at cross-section 4
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-3 Appendix A – Representative Photographs
Suncook River – Old Primary Channel
Looking upstream at cross-section 5
Looking at left bank at cross-section 3
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-4 Appendix A – Representative Photographs
Suncook River – Avulsion – New Channel
Looking upstream at cross-section 1 above the avulsion
Looking downstream at cross-section 2 above avulsion
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-5 Appendix A – Representative Photographs
Suncook River – Avulsion – New Channel
Looking at right bank and at abandoned channel at cross-section 3
Looking upstream at cross-section 3
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-6 Appendix A – Representative Photographs
Suncook River – Avulsion – New Channel
Looking at left bank at cross-section 4
Looking upstream at cross-section 10
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-7 Appendix A – Representative Photographs
Suncook River – Old Side Channel
Looking upstream at side channel cross-section
Looking downstream at side channel cross-section
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-8 Appendix A – Representative Photographs
Suncook River – Confluence Area
Looking downstream at cross-section 2 above confluence with abandoned channel
Looking at right bank at the confluence of the abandoned and new channel
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-9 Appendix A – Representative Photographs
Suncook River – Confluence Area
Looking at sand deposit on right bank below confluence
Looking at left bank and at floodplain below Round Pond
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx A-10 Appendix A – Representative Photographs
Suncook River – Confluence Area
Looking downstream at cross-section 8
Looking at right bank between cross-section 3 and 4
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx B-1 Appendix B – Hydrological and Geomorphic Data
Appendix B
Hydrological and Geomorphic Data (PARISH Geomorphic)
B-2 Appendix B – Hydrological and Geomorphic Data
Figure C-1: Key to the locations of detailed field sites on the Suncook River, Epsom, NH.
B-3 Appendix B – Hydrological and Geomorphic Data
New Channel
�4
�2
0
2
4
6
8
10
12
14
16
18
0 20 40 60 80 100 120 140 160 180
Dep
th�(ft)
Width�(ft)
New�Channel�� Cross�section�1
Channel�Bed
0
5
10
15
20
25
0 50 100 150 200
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�2
Channel�Bed
B-4 Appendix B – Hydrological and Geomorphic Data
0
5
10
15
20
25
0 50 100 150 200
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�3
Channel�Bed
�2
0
2
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6
8
10
12
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)
New�Channel�� Cross�section�4
Channel�Bed
B-5 Appendix B – Hydrological and Geomorphic Data
0
2
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6
8
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12
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�5
Channel�Bed
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140 160 180
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�6
Channel�Bed
B-6 Appendix B – Hydrological and Geomorphic Data
0
2
4
6
8
10
12
0 50 100 150 200 250
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�7
Channel�Bed
0
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10
15
20
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0 50 100 150 200 250
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�8
Channel�Bed
B-7 Appendix B – Hydrological and Geomorphic Data
0
2
4
6
8
10
12
14
16
0 20 40 60 80 100 120 140 160 180 200
Dep
th�(ft)
Width�(ft)New�Channel�� Cross�section�9
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12
0 20 40 60 80 100 120 140 160 180 200
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New�Channel�� Cross�section�10
Series1
B-8 Appendix B – Hydrological and Geomorphic Data
FLUVIAL GEOMORPHOLOGY SUMMARYSuncook RiverSite Location: New Channel Number of cross-sections: 10 Date of Survey: July 9th, 2007
Controlling Factors
Upstream Drainage Area: 407 km2 Geology / Soils: alluvial
Modifying Factors
Surrounding Land Use: forest/gravel pit General Riparian Vegetation: forest Existing Channel Disturbances: dams on the old primary and secondary channels Woody Debris: major
Cross-Sectional Characteristics
Range AverageBankfull Width (ft) 141.66 - 233.70 187.77 Bankfull Depth (ft) 0.58 - 17.38 1.00 Width / Depth 12.34 - 28.34 19.06 Entrenchment (ft) 151.50 - 325.96 22.06 Entrenchment Ratio 1.00 - 2.01 1.28 Manning's n 0.035
Bank Characteristics
Range Average Bank Height (ft) 6.07 - 36.09 11.16 Bank Angle (degrees) 0 - 63.3 27.49 Root Depth (inches) 0.0 - 15.75 2.4 Root Density (1=Low - 5=High) 1 - 4 2.1 Protected by vegetation (%) 0 - 100 21.8 Amount of undercut (inches) 0.0 - 11.81 0.85 Banks with undercuts (%) 21%
Bank Materials Torvane values (kg/cm2)S,Cl 1.46 S, Si, Cl,P 0.81 S,Si,Cl 2.00 Cl 2.50 S 0.63
SubstratParticle
Hydraul
EmbeddSub-pav
ParticlePebble C
Field ObXs 1 Boulbanks butXs 2 Largbank) Xs 6 left bbank, nonXs 8 fast
Xs 10 end
te CharacterisShape (inch
ic Roughnes
dedness (%) vement
Sizes (cm) Counts
bservations der riffle, rivet channel doee gravel/cobb
bank highly vene near watert moving wated of pit area, s
B-9 Ap
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XYZ
ss (cm) MaximuMedian Minimum
Cl 22 Si 1Vfs 10 Fs 11 Ms 3.5Cs 16 Vcs 4.2
D10 D50 D90
er appears to es not appear ble mid chann
egetated on tor on left side. er, gravel barsignificant wo
ppendix B – H
Range1.18 - 27.160.39 - 20.080.39 - 14.96
m 0 - 51.180 - 13.78
m 0 - 1.970 - 100
1.969E-050.11 inches1.66 inches
begin to unrato be over w
nel bar diverti
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Hydrological a
Average6 4.18 3.36 2.2
11.5 3.1 0.4 52.2
P 8.80.3937 "0.59" 1.0.7874"1.18" 8.61.57" 1.1.97" 6B dr. 0.5
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ng density at t
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B-10 Appendix B – Hydrological and Geomorphic Data
Old Primary Channel
�3
�2
�1
0
1
2
3
4
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)
Old�Primary�Channel�� Cross�section�1
Channel�bedBankfull
�1
0
1
2
3
4
5
0 10 20 30 40 50 60 70 80 90
Dep
th�(ft)
Width�(ft)
Old�Primary�Channel�� Cross�section�2
Channel�Bed
Bankfull
B-11 Appendix B – Hydrological and Geomorphic Data
�1
0
1
2
3
4
5
6
7
8
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)Old�Primary��Channel�� Cross�section�3
Channel�BedBankfull
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)Old��Primary�Channel�� Cross�section�4
Channel�Bed
Bankfull
B-12 Appendix B – Hydrological and Geomorphic Data
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140 160 180
Dep
th�(m
)
Width�(m)Old��Primary�Channel�� Cross�section�5
Channel�BedBankfull
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100 120 140 160 180 200
Dep
th�(ft)
Width�(ft)Old�Primary�Channel�� Cross�section�6
Channel�bedBankfull
B-13 Appendix B – Hydrological and Geomorphic Data
FLUVIAL GEOMORPHOLOGY SUMMARYSuncook Old Primary ChannelSite Location: Old Primary channel west of Bear Island Length surveyed: NANumber of cross-sections: 6Date of Survey: 10-Jul-07 Controlling Factors
Upstream Drainage Area: 407 km2 Geology / Soils: bedrock (predominant)
Modifying Factors
Surrounding Land Use: forest/scrub/farm General Riparian Vegetation: forest/scrub Existing Channel Disturbances: Bridge upstream of avulsion, dams on both old channels
Woody Debris:
Cross-Sectional Characteristics
Range Average Bankfull Width (ft) 78.29 - 0.00 91.14 Bankfull Depth (ft) 2.12 - 3.67 2.86 Width / Depth 22.21 - 41.25 32.56 Entrenchment (m) 121.76 - 162.38 135.15 Entrenchment Ratio 1.32 - 1.75 1.51 Manning's n 0.035
Bank Characteristics
Range Average
Bank Height (inches) 3.281 - 6.562 0.541 Bank Angle (degrees) 7.5 - 50 22.625 Root Depth (inches) 0.8 - 3.979 2.1 Root Density (1=Low - 5=High) 2 - 3 2.5 Protected by vegetation (%) 60 - 100 82.5 Amount of undercut (inches) 0.0 - 59.055 5.052 Banks with undercuts (%) Bank Materials Torvane values (kg/cm2) S, Org 3.19 Cbl, Org, Bedrock 4.00 Org 2.00 S, Cl, Org 3.00
B-14 Appendix B – Hydrological and Geomorphic Data
Substrate Characteristics Particle Shape (inches) Range Average X 0.394 - 13.386 5.2 Y 0.394 - 10.630 3.8 Z 0.394 - 7.087 2.5
Hydraulic Roughness (inches) Maximum 9.843 - 37.0078 20.9 Median 1.969 - 9.8425 5.0 Minimum 0 - 1.969 0.8 Embeddedness (%) 20 - 50 26.0 Sub-pavement Cl 0 P 16.6666667 Si 16.666667 0.3937 " 0 Vfs 0 0.59" 0 Fs 16.666667 0.7874" 0
Ms 16.666667 1.18" 0Cs 16.666667 1.57" 0Vcs 16.666667 1.97" 0
Bdr. 0 Particle Sizes (inches
Pebble Counts D10 0.196 inchesD50 6.93 inches D90 24.22 inches
Field Observations xs 3 muskrat in pool, large erratic, pool bottom made up of cobble and boulders xs 4 cobble boulder bottomxs 6 leaves in bottom of stream very silty
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Cla
yS
iltV
FS FS MS
CS
VC
Spe
bble
sFG M
GM
GC
GC
GV
CG
VC
G SC
SC LC LC SB
SB
MB LB
VLB
VLB
Cum
ulat
ive
Perc
ent
Tota
l Per
cent
Particle Size (cm)
Substrate Size Distribution -
Total %Cumulative %
B-15 Appendix B – Hydrological and Geomorphic Data
Old Side Channel
Side�Channel���Cross�section�1
0
1
2
3
4
5
6
0 10 20 30 40 50 60
Width�(ft)
Depth�(f
Channel�BedBankfull
B-16 Appendix B – Hydrological and Geomorphic Data
FLUVIAL GEOMORPHOLOGY SUMMARYOld Side Channel
Site Location: Old Side Channel Number of cross-sections: 1Date of Survey: July 9th, 2007
Controlling Factors
Upstream Drainage Area: 407 km2 Geology / Soils: alluvial
Modifying Factors
Surrounding Land Use: forest/gravel pit General Riparian Vegetation: forest Existing Channel Disturbances: dams on the old primary and secondary channels
Woody Debris: minor
Cross-Sectional Characteristics
Range AverageBankfull Width (ft) 55.4Bankfull Depth (ft) 4.81Width / Depth 11.51Entrenchment (ft) 105.0Entrenchment Ratio 1.9Manning's n .035
Bank Characteristics
Bank Height (ft) 1.15 Bank Angle (degrees) 53 Root Depth (inches) 23.5 Root Density (1=Low - 5=High) 3 Protected by vegetation (%) 100 Amount of undercut (inches) 7 Banks with undercuts (%) 21
Bank Materials Torvane values (kg/cm2)S,Cl 2.77
Substrate Characteristics
Particle Shape (cm) Range Average X 5-24 15.3 Y 2-16 8.0 Z 4-10 7.7
Hydraulic Roughness (cm) Maximum 84 Median 36 Minimum 5
B-17 Appendix B – Hydrological and Geomorphic Data
Embeddedness (%) 15 Sub-pavement cl 0 P 0 si 0 0.3937 " 0 vfs 0 0.59" 0 fs 0 0.7874" 0
ms 0 1.18" 0cs 0 1.57" 0vcs 0 1.97" 0
Bdr. 100 Particle Sizes (cm)
Pebble CountsD10 .049 D50 4.79 D90 102.39
Substrate Size Distribution -
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
< .0
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3.19
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9.59
9.6-
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9
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9.6
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Particle Size (cm)
Tota
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20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Cum
ulat
ive
Perc
Total %
Cumulative %
B-18 Appendix B – Hydrological and Geomorphic Data
Confluence Area
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Dep
th�(ft)
Width�(ft)
Confluence�Area� Cross�section�1
Channel�bed
Bankfull
�1
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1
2
3
4
5
6
7
8
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)
Confluence�Area� Cross�section�2
Channel�Bed
Bankfull
B-19 Appendix B – Hydrological and Geomorphic Data
�1
0
1
2
3
4
5
6
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)Confluence�Area� Cross�section�3
Channel�BedBankfull
�3
�2
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0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)
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Channel�bedBankfull
B-20 Appendix B – Hydrological and Geomorphic Data
�1
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)Confluence�Area�� Cross�section�5
Channel�BedBankfull
�2
�1
0
1
2
3
4
5
0 20 40 60 80 100 120 140
Dep
th�(ft)
Width�(ft)Confluence�Area�� Cross�section�6
Top�of�BankWater
B-21 Appendix B – Hydrological and Geomorphic Data
�2
�1
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)Confluence�Area�� Cross�section�7
Channel�BedBankfull
�3
�2
�1
0
1
2
3
4
5
0 20 40 60 80 100 120 140 160
Dep
th�(ft)
Width�(ft)
Confluence�Area�� Cross�section�8
Channel�BedBankfull
B-22 Appendix B – Hydrological and Geomorphic Data
�4
�3
�2
�1
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160 180
Dep
th�(ft)
Width�(ft)Confluence�Area�� Cross�section�9
Top�of�BankWater
B-23 Appendix B – Hydrological and Geomorphic Data
FLUVIAL GEOMORPHOLOGY SUMMARY Suncook River
Site Location: Confluence of old and new channels Number of cross-sections: 9 Date of Survey: July 9 2007 Controlling FactorsUpstream Drainage Area: 407 km2 Geology / Soils: alluvial Modifying Factors
Surrounding Land Use: forest General Riparian Vegetation: forest Existing Channel Disturbances: Dams on Old Primary and Side channels Woody Debris: Major
Cross-Sectional Characteristics
Range Average Bankfull Width (ft) 61.13 - 132.32 102.44 Bankfull Depth (ft) 1.20 - 5.79 3.14 Width / Depth 14.14 - 71.43 38.81 Entrenchment (ft) 0.00 - 132.32 92.19 Entrenchment Ratio 1.00 - 1.00 1.00 Manning's n 0.035
Bank Characteristics
Range Average Bank Height (ft) 0.34 - 9.84 5.66 Bank Angle (degrees) 1 - 90 21.34 Root Depth (inches) 0.00 - 11.81 3.43 Root Density (1=Low - 5=High) 1 - 4 2.2 Protected by vegetation (%) 0 - 90 45.7 Amount of undercut (inches) 0.00 - 1.18 0.11 Banks with undercuts (%) 21%
Bank Materials Torvane values (kg/cm2) VFS, Cl 0.88 Cl, S, Org 2.30 Cl,S,Cbl, Org 1.07 VFS,FS,MS,Cl 0.66 Cl, FS 0.54 Substrate Characteristics Particle Shape (cm) Range Average
X 0.39 - 5.51 0.89 Y 0.39 - 2.76 0.61 Z 0.2 - 2.76 0.51
Hydraulic Roughness (cm) Maximum 11.81 - 35.83 9.38
B-24 Appendix B – Hydrological and Geomorphic Data
Median 15.75 - 15.75 6.20 Minimum 0 - 0 0.00 Embeddedness (%) 1 - 100 154.09 Sub-pavement Cl 3.125 P 11.25 Si 0 0.3937 " 0 Vfs 0 0.59" 0 Fs 10 0.7874" 1.25
Ms 23.125 1.18" 8.125 Cs 37.5 1.57" 3.875 Vcs 0 1.97" 1.75
Bdr. 0 Particle Sizes (cm)
Pebble Counts D10 0.00 inches D50 0.23 inches D90 1.81 inches
Field Observations
xs 1 right banks natural bank is exposed with only a .5 m amount of sand on top, Terrestrial plants under water on right bank xs 3 old channel one pool like here, saw 6" catfish xs 4 LB no growth on all of the gravel part of the bank, normal topsoil appears about 2 vertical m up from in RB growth of plants in water, poison ivy growing through sand xs 6 no roughness indicators, except 1 lump of clay. LB is a deposit burying tree roots
xs 7 valley wall is bank of rand pond, beyond the pond edge next to river, valley wall is over 100m
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Cla
yS
iltV
FS FS MS
CS
VC
Spe
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sFG M
GM
GC
GC
GV
CG
VC
G SC
SC LC LC SB
SB
MB LB
VLB
VLB
Cum
ulat
ive
Perc
ent
Tota
l Per
cent
Particle Size (cm)
Substrate Size Distribution -
Total %
B-25 Appendix B – Hydrological and Geomorphic Data
Short Falls Area
Short�Falls�Area���Cross�section�1
�1
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160
Width�(ft)
Depth�(f
Channel�BedBankfull
Short Falls Area - Cross-section 2
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600
Width (ft)
Dep
th (f
Cross-Section 2
Bankfull
B-26 Appendix B – Hydrological and Geomorphic Data
Reference Reach
�1
0
1
2
3
4
5
6
0 10 20 30 40 50 60 70 80 90
Dep
th�(ft)
Width�(ft)Reference�Reach�� Cross�section�1
Channel�bed
Bankfull
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100
Dep
th�(ft)
Width�(ft)Reference�Reach�� Cross�section�2
Channel�Bed
Bankfull
B-27 Appendix B – Hydrological and Geomorphic Data
�4
�2
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Dep
th�(ft)
Width�(ft)
Reference�Reach�� Cross�section�3
Channel�bed
Bankfull
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80 90 100
Dep
th�(ft)
Width�(ft)Reference�Reach�� Cross�section�4
Channel�bed
Bankfull
B-28 Appendix B – Hydrological and Geomorphic Data
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Dep
th�(ft)
Width�(ft)
Reference�Reach�� Cross�section�5
Channel�bed
Bankfull
B-29 Appendix B – Hydrological and Geomorphic Data
FLUVIAL GEOMORPHOLOGY SUMMARY
Suncook Reference Reach Site Location: Reference Length surveyed: 0 Ft Number of cross-sections: 5Date of Survey:10-Jul-07 Modifying Factors
Surrounding Land Use: forest/agricultural General Riparian Vegetation: forest Existing Channel Disturbances:
Woody Debris:
Cross-Sectional Characteristics
Range Average Bankfull Width (ft) 77.17 - 110.78 91.87 Bankfull Depth (ft) 2.25 - 8.95 4.74 Width / Depth 12.38 - 34.27 23.30 Entrenchment (ft) 116.54 - 150.15 136.49 Entrenchment Ratio 1.36 - 1.66 1.49 Manning's n
Bank Characteristics
Range Average Bank Height (ft) 3.28 - 6.56 4.51 Bank Angle (degrees) 7.5 - 50 22.625 Root Depth (inches) 0.8 - 3.94 2.1 Root Density (1=Low - 5=High) 2 - 3 2.5 Protected by vegetation (%) 60 - 100 82.5 Amount of undercut (inches) 0.0 - 59.06 5.052 Banks with undercuts (%) 21%
Bank Materials Torvane values (kg/cm2) S, Org 3.19 Cbl, Org, Bedrock 4.00 Org 2.00 S, Cl, Org 3.00 0 Substrate Characteristics Particle Shape (inches) Range Average X 0.39 - 13.39 5.2 Y 0.39 - 10.63 3.8 Z 0.39 - 7.09 2.5
Hydraulic Roughness (inches) Maximum 9.84 - 37.01 20.9
J:\51892.00\reports\Dra19\Appendices\Append
EmbeddSub-pav
Particle
aft_Final_Report_May_ices.docx
MedMini
dedness (%) vement
Cl 0Si 16Vfs 0Fs 1Ms 1Cs 1Vcs
Sizes (cm)
D10 D50 D90
B-30 Ap
dianmum
6.6706.67
16.67 16.67 16.67
ppendix B – H
1.97 - 90 - 1.9720 - 50
P0.39370.59"0.7874"1.18"1.57"1.97"Bdr.
Pebbleinchesinchesinches
Hydrological a
9.84 5.07 0.8
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0" 0
0000
Counts
and Geomorp
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phic Data
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-1 Appendix C – Geomorphic Analysis
Appendix C
Geomorphic Analysis
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-2 Appendix C – Geomorphic Analysis
Bankfull Discharge Estimates
Old Primary Channel, Bankfull Discharge Estimates
0
200
400
600
800
1000
1200
1400
1600
1800
XS-Ref-1 XS-Ref-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10
Cross-Section
cfs
)
BrownlieManning'sCowanStricklerL,W, and MLimerinosBrayGriffithsEffective QSELECTED BANKFULL DISHARGE = 2-yearRegional Curve1.25 -yearAverage
Old Side Channel, Bankfull Discharge Estimates
0
200
400
600
800
1000
1200
1400
XS-Ref-1 XS-Ref-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10
Cross-Section
cfs
)
BrownlieManning'sCowanStricklerL,W, and MLimerinosBrayGriffithsEffective QSELECTED BANKFULL DISHARGE = 2-yearRegional Curve1.25 -yearAverage
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Confluence Area, Bankfull Discharge Estimates
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Cross-Section
cfs
)
BrownlieManning'sCowanStricklerL,W, and MLimerinosBrayGriffithsEffective QSELECTED BANKFULL DISHARGE = 2-yearRegional Curve1.25 -yearAverage
Short Falls Area, Bankfull Discharge Estimates
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XS-Ref-1 XS-Ref-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10
Cross-Section
cfs
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BrownlieManning'sCowanStricklerL,W, and MLimerinosBrayGriffithsEffective QSELECTED BANKFULL DISHARGE = 2-yearRegional Curve1.25 -yearAverage
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-4 Appendix C – Geomorphic Analysis
Reference Reach, Bankfull Discharge Estimates
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Cross-Section
cfs
BrownlieManning'sCowanStricklerL,W, and MLimerinosBrayGriffithsEffective QSELECTED BANKFULL DISHARGE = 2-yearRegional Curve1.25 -yearAverage
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-5 Appendix C – Geomorphic Analysis
Hydraulic Geometry
Old Primary Channel- Hydraulic Geometry
0102030405060708090
100110120130140150160170180190200210220230240250260270280290300310320330340350360
XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
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Old Primary Channel - Hydraulic Geometry
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Bankfull Depth (ft)Hydralic Bankfull Depth (ft)Hydraulic Radius (ft)
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-6 Appendix C – Geomorphic Analysis
Old Side Channel - Hydraulic Geometry
0102030405060708090
100110120130140150160170180190200
XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
Wet Perim (ft)Bankfull Area (sft)Banfull Width (ft)W/D Ratio
Old Side Channel - Hydraulic Geometry
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Bankfull Depth (ft)Hydralic Bankfull Depth (ft)Hydraulic Radius (ft)
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-7 Appendix C – Geomorphic Analysis
Confluence - Hydraulic Geometry
0102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360370380390400410420430440450460470480490500510520
XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
Wet Perim (ft)Bankfull Area (sft)Banfull Width (ft)W/D Ratio
Confluance - Hydraulic Geometry
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Bankfull Depth (ft)Hydralic Bankfull Depth (ft)Hydraulic Radius (ft)
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-8 Appendix C – Geomorphic Analysis
Short Falls - Hydraulic Geometry
0200400600800
1000120014001600180020002200240026002800300032003400360038004000420044004600
XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
Wet Perim (ft)Bankfull Area (sft)Banfull Width (ft)W/D Ratio
Short Falls - Hydraulic Geomoetry
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Bankfull Depth (ft)Hydralic Bankfull Depth (ft)Hydraulic Radius (ft)
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-9 Appendix C – Geomorphic Analysis
Reference Reach - Hydraulic Geometry
0102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360370380390400410420430440450460470480490500510520530
XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
Wet Perim (ft)Bankfull Area (sft)Banfull Width (ft)W/D Ratio
Reference Reach - Hydraulic Geometry
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XS-REF-1 XS-REF-2 XS-1 XS-2 XS-3 XS-4 XS-5 XS-6 XS-7 XS-8 XS-9 XS-10 XS-tmplt-1 XS-tmplt-2
Bankfull Depth (ft)Hydralic Bankfull Depth (ft)Hydraulic Radius (ft)
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx C-10 Appendix C – Geomorphic Analysis
Regional Curves
From: NHDES and NHDOT (2005), Guidelines for Naturalized River Channel Design and Bank Stabilization
J:\51892.00\reports\Draft_Final_Report_May_19\Appendices\Appendices.docx Appendix D – Whittkop (2008)
Appendix D
Whittkop (2008)
Suncook River Long Term Observations
DEPARTMENT OF CHEMISTRY AND GEOLOGY 242 TRAFTON SCIENCE CENTER N · MANKATO, MN 56001
PHONE 507-389-1963 (V) · 800-627-3529 OR 711 (MRS/TTY) · FAX 507-389-5625 An Affirmative Action/Equal Opportunity University.
To: David Wunsch, State Geologist Rick Chormann, Senior Hydrologist, NHGS, NHDES Steve Couture, Rivers Coordinator, NHDES Peter J. Walker, VHB
From: Chad Wittkop Date: February 24, 2008
RE: Suncook River long-term observations
I write to share my long-term observations of the new channel of the Suncook River in Epsom, New Hampshire. This document is intended to serve as an addendum to the Northeastern GSA field guide published in spring 2007, which described the basic geology of the site and outlined the causes of the avulsion. Since assembling the field guide, I have made two more trips to the site—one during the Northeastern GSA field trip in March 2007, and another more extensive examination over several days in late July 2007.
During the more recent visit, a student assistant and I collected new differential GPS data to record changes in the position of the new channel. Additional comparisons were made using digital photos, field relationships, and anecdotal accounts of Epsom residents. I have also recently received 1-foot contours and May 2007 orthophotos courtesy of Mr. Couture and the Town of Epsom, and have begun incorporating these valuable data in my ongoing analysis.
Results of my long term observations are grouped into themes below.
I. Erosion and the New Channel
Differential GPS data were collected in May and June of 2006 in effort to map the position of the new channel. Among the features documented at the time were positions of banks, areas of avulsion-related erosion, and knickpoints. Using GIS, I compared the location of the 2006 features with new GPS data collected in July 2007. This analysis shows:
� Portions of the new channel have migrated laterally a minimum of 150 feet to the south-southeast. Examination of three sets of digital photos taken from the same vantage in May 2006, March 2007, and July 2007 clearly show this erosion, the bulk of which appears to have taken place between March 2007 and July 2007 (Figures 1 & 2).
� Lateral migration of the new channel to the southwest has eroded up to 80 feet of a gravel ridge near the capture point of the old channel.
� Digital elevation models derived from the 1-foot contour data developed by Eastern Topographics allow incision in the new channel to be quantified (Figure 3). At the capture point of the new channel, 14 feet of incision has occurred between the thalweg of the former channel and the water surface of the new channel. In the center of the new channel, 24 feet of incision has occurred between the former wetland surface and the new channel water surface.
� As a result of the incision described above, severe headcutting and associated bank failures have developed upstream of the capture point. Significant bank failures have occurred as far as 2,500 feet upstream from the new channel capture point.
Chad Wittkop February 24, 2008 Suncook Long-Term Observations Page 2
� Headcuts are also progressing upstream in tributaries whose base-levels were altered by the incision. A knickpoint on a small tributary of the Suncook, Leighton Brook, migrated upstream over 300 feet between May 2006 and July 2007. Similar incision displaced granite cribbing on the railroad grade crossing the Little Suncook River, which is only 1000 feet downstream from the Route 4 bridge.
� Incision upstream of the capture point has exposed boulders identified as local bedrock (Rangeley formation; Peter Thompson, personal communication). The presence of bedrock may inhibit further incision, but unrestricted lateral erosion could allow the channel to bypass bedrock knobs and allow a new cycle of incision. The topography of the bedrock surface in this area is unknown, and geophysical surveys and/or drilling would be required to examine this issue in depth.
� Upstream of Route 4, residents have reported subtler changes in the river and a lower water table, which are likely related to the increased gradient and drop in base level associated with the avulsion. Owners and residents of the Epsom Valley campground north of Route 4 report that since the avulsion the river level is lower and has become flashier. In the campground, portions of bank have failed resulting in the loss of several mature white pine trees, and the water level in an oxbow pond has dropped as much as 3 feet.
II. Depositional Features Severe aggradation (channel filling), is evident from the new channel south to Short Falls. In 2006 I estimated as much as 150,000 cubic yards of sediment was introduced to the Suncook as a result of the avulsion. I have not had a chance to refine this estimate, but the significant post-avulsion erosion described above is providing a continued supply of sediment downstream of the avulsion site. Impacts of this deposition include:
� Comparison of 2005 aerial photos and 2007 GPS data reveals a delta building into the north end of Round Pond near the Epsom well house (Figure 4). As much as 125 feet of open water has been filled with delta sediment. Two outlet channels have developed at the southeastern corner of Round Pond, and likely contain significant discharge during flood events.
� Aggradation to bankfull height in portions of the reach between the southern tip of Bear Island and a series of tight meanders above Short Falls. An active cutoff channel is developing in the area, and will likely overtake the previous channel, which is superelevated (main channel bed is higher than the cutoff) relative to the cutoff (Figure 4). If it completes, the cutoff will abandon an additional 1,700 feet of channel for a new course that is approximately 700 feet long.
III. Stratigraphy of the New Channel
Ongoing incision in the new channel reveals a clearer picture of the stratigraphy of Pleistocene and Holocene deposits in the avulsion area. These sediments were initially described in the 2007 field guide, but a more coherent synthesis of this stratigraphy is offered below (Figure 5).
� A silty glacial till was observed in deeply incised-portions of the channel near the capture point. The sediment contained cobble-sized clasts in a silty, dark gray matrix. In New Hampshire, this type of sediment is often described as an “Illinoian” (i.e. old) till but no age relationship is implied here beyond its relative stratigraphic position.
� Glacial lake sediments occur stratigraphically above the till. Additional exposure of deformed, silty glacial lake beds near the capture point suggests an overall coarsening upward sequence in
Chad Wittkop February 24, 2008 Suncook Long-Term Observations Page 3
the sediments exposed there, from silt to fine sand to sand and gravel, with the coarsest sediment occurring in glaciofluvial deposits that form the higher ridges in the valley. The coarsening upward sequence, combined with the presence of deformed lake beds, is suggestive of an increasing proximity to the glacial margin with time, i.e. a local glacial advance or re-advance.
� A Holocene fluvial sequence is well exposed in the new channel, displaying broad, gently dipping lateral accretion surfaces, which are formed by lateral migration of pointbars in a meandering river system. These sandy, post-glacial fluvial sediments can be distinguished from sandy glacial sediments by their unoxidized (white to gray) color, the presence of dark stringers of organic-rich sediments, and by the presence of lateral accretion surfaces. Vivianite-bearing, silty wetland sediments described in the 2007 field guide likely represent vertically accreting channel fill (oxbow) sediments.
� The presence of Holocene fluvial sediments underlying much of the new channel suggests that the Suncook flowed through areas occupied by portions of the new channel in the past, but was unable to completely breach the coarse-grained glacial ridge to initiate an avulsion.
IV. Impoundments and Gradients
The large-scale patterns of erosion and deposition described are consistent with the steeper gradient and increased stream power resulting from the avulsion. The impoundment at Hukins Mill dam acted to maintain a very low gradient in the Suncook upstream of the site. Loss of this impoundment and the increased gradient of the new channel is also consistent with the reports of lower water tables and increased flashiness in the stream above Route 4.
In the absence of an impoundment at Hukins Mill, roadbank fill in the floodplain along U.S. Route 4 may act in part as an impoundment during high flow events, such as the April 2007 flood. This may have the effect of further concentrating flow downstream of Route 4 as the bridge opening acts as a spillway-like constriction. Left unmitigated this situation, particularly when combined with the upstream migration of headcuts from the avulsion site, could compromise the Route 4 bridge.
Chad Wittkop February 24, 2008 Suncook Long-Term Observations Page 4
Chad Wittkop February 24, 2008 Suncook Long-Term Observations Page 5
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