lewis creek reach m19 phase 1, phase 2, and phase 3
Post on 19-Dec-2015
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Lewis Creek Reach M19Lewis Creek Reach M19
Phase 1, Phase 2, and Phase 3Phase 1, Phase 2, and Phase 3
Lewis Creek Watershed
M19
Phases of Assessment• Phase 1 - Remote Sensing and Existing Data
• Phase 2 - Qualitative and Rapid Field Assessment
• Phase 3 - Field Survey Assessment
Watershed Reach
and Segment-Level Approaches
Topographic lines overlaid on Orthos
Local Knowledge and NRCS Information1) Channelization upstream of farm
bridge occurred in 60’s2) Rip-rap routinely installed since at
least early 80’s3) Current farm bridge moved to new
location in 19814) Past landowners did channel
“work” to maintain straighter channel
5) High floods in the late 1980’s6) Out of bank flows occur about every
2 years, flashy events every year7) Entire valley bottom has been
flooded in past8) Soil cores done on Lewis Creek
Farm confirm presence of glacial lake clays in valley bottom
9) Bank re-vegetation projects occurred in 1990’s on Lewis Creek Farm
1905
1983
Topographic Map Comparison
1942 1995
Orthophoto Comparison
Changes in Planform
1983 Topographic Map
(Corridor is approx 475 ft wide at ball field area and approx 375 ft wide along the remainder of the reach)
Phase 1 River Corridor
Parameters evaluated in Phase 1 Corridor
1) Soils and Geology
2) Land Use and Land Cover
3) Riparian Vegetation
4) Berms, Roads & Improved Paths
5) Development
Soils Data and approximate
Valley Wall Lines Corridor where soils reviewed
Approximate valley wall
Parent Material
Flood Potential
Slope Types
Various types of soil parameters that can be evaluated using the soil maps.
Reach Number
Stream Type
Total impact
(out of 32)
Step 4 Land Use
Impact (out of 6)
Step 5 Instream
Modification Impact (out of 10)
Step 6 Floodplain
Modification Impact (out of 12)
Step 7 Windshield
Survey Impact
(out of 4)
Watershed Size
Confinement
M19 C 14 3 4 5 2 18.21 3-VB
Types of Impacts seen along stream reach:
1) Active Agriculture in corridor (crop) {Step 4}2) Little to no Riparian vegetation {Step 4}3) Channel modification (straightening) {Step 5}4) Bank Armoring (Rock rip-rap) {Step 5}5) Mid-channel bars {Step 6}6) Planform changes (meander migration & avulsions) {Step 6}7) Erosion {Step 7}
Phase 2, Rapid Field Assessment
Field verification of Phase 1 data
Collecting data using the Field Form, Rapid Habitat & Geomorphic Assessments
Identifying condition and stream type of the reach
Geomorphic and Habitat AssessmentAssessment Objectives
• Identification of:
– stream condition as compared to a reference stream of the same type
– adjustment process or physical change currently underway in the channel
– sensitivity of valley, floodplain, and channel to human or natural changes
Examples of field parameters evaluated• Valley & Floodplain Corridor Land Use/Land Cover• Soils and Geology• Riparian Vegetation• Bankfull Height and Flood-prone Width• Habitat Conditions
Evaluating:•Bank Vegetation•Riparian Vegetation•Corridor Land Use
Measuring channel data:•Width•Depth•Flood Prone Width•Entrenchment
Enjoying the point bar for a break and review of
parameters. *Sediment size on point bar*Sediment size in different bed features
Measuring the distance
between riffles
Noting:•Bank Erosion and Scour•Bank Slope
Recording Types of Bank Protection:•Rip-rap•Tree revetments
Sediment types seen along reach:1) Gravels2) Sands3) Clays and silts
Comparison of upper and lower bank material
Fines
Small gravels
Evaluating types of bed sediment storage seen:•Mid-channel bars•Point bars•Diagonal Bars
BD
BD
Beaver Activity
May Affect Stream by:
1) Changing water levels2) Altering Sediment deposition locations3) Influencing planform changes4) Creating or changing habitat features
Reach Number Segment
Bankfull Width
(ft)
Flood-prone Width
(ft)
Max Depth
(ft)
Low Bank
Height (ft)
Entrench-ment
Width/Depth Ratio Sinuosity
Channel Slope
(Phase1)Incision
Ratio
Stream Type
Stream Type Bed
Material
Stream Bed
Feature Type
M19 A 40 500 3 - 4.5 18.7 Moderate 0.40% - C 4Riffle-Pool
*M19 B 69 500 4 - 7.2 24.4 Moderate 0.40% - C 4Riffle-Pool
Reach Number Segment
Habitat Condition
Geomorphic Condition
Dominant Adjustment
Process
Concurrent Adjustment
ProcessStage of Channel
Evolution
* Channel Sensitivity to Disturbance
M19 A Poor Poor Widening Aggredation Widening –III /IVvery high to
extreme
*M19 B Fair Fair Aggredation Widening Widening –III /IVvery high to
extreme
Some of the things that affected the habitat were:1)Sediment deposition, embedded riffles
2) Lack of riffles and fast deep water,
3) Low diversity of substrate for epifaunal colonization
4) Bank stability / erosion, and
5) Poor riparian buffer protection.
* There are good pools in the reach, and many small black-nose dace and creek-chubs were seen. * The upstream half does have good shading from a treed buffer of 25ft to 50ft wide; the
downstream buffer mainly herbaceous with a few shrubs and trees mixed in, so little shade is
provided to the stream in this section.
Some things that affected the geomorphic condition were:1) Small amount of channel incision
2) Sedimentation
3) Bank failure and scour – over widened channel in locations
4) Changes in planform; avulsions, channel bars, and thalweg not always lined up with planform
Phase 3 , Survey Level Assessment
• Further verify the stream type.
• Establish cross-sections for long term monitoring
• Evaluate sediment size being transported by stream
Lewis Creek at North Ferrisburg, VT
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1990 1992 1994 1996 1998 2000
Annual Peaks 10 yr Discharge 25 yr Discharge 50 yr Discharge
1990 1991 1994 1996 1998 2000
1912191419161917192019221927193019321934193619381940194219441946194819501952195419561958195919621964196619681970197219731976197719801982198419861988199019921994199619982000
Flood History
Otter Creek at Middlebury, VT
0
2000
4000
6000
8000
10000
12000
14000
16000
1904190619121914191619181927193019321934193619381940194219441946194819501952195419561958196019621964196619681970197219741976197819801982198419861987199019921994199619982000
Annual Peaks 10 yr Discharge 25 yr Discharge 50 yr Discharge
1990 1993 1995 1996 1999 2000
1990 1992 1994 1996 1998 2000
From Gage Records
Bankfull stage flows in spring of 2002
Bankfull stage flows in spring of 2002
Lewis Creek
-100
-50
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700-1100-1050-1000-950-900-850-800-750-700-650-600-550-500-450-400-350-300-250-200-150-100-50 0
East West Distance (ft)
North South Distance (ft)
XS 4
XS 5
XS 3
XS 2
XS 1
Channel Planform and
Cross-section Location
5 Monumented Cross-sections
established
Measuring Bankfull and Flood-prone Width
Flood-prone elevation
Bankfull elevation
Lewis Creek 1
10
12
14
16
18
20
22
0 20 40 60 80 100 120 140 160
Distance From Lef t Bank (f t)
Elevation (ft)
XS –1RiffleWidth = 33 ftMax Depth = 3.45 ftFPW = ~150 ftD50 = 10.66 mm (medium gravel)Stream Type = C4
Lewis Creek 2
10
12
14
16
18
20
22
0 10 20 30 40 50 60 70 80
Distance From Lef t Bank (f t)
Elevation (ft)
XS –2RunWidth = 31.74 ftMax Depth = 4.03 ftFPW = ~200 ftD50 = 1.34 mm (very coarse sand)Stream Type = E5
Lewis Creek 3
10
12
14
16
18
20
22
0 10 20 30 40 50 60 70
Distance From Left Bank (ft)
Elevation (ft)
XS – 3RunWidth = 27.49 ftMax Depth = 3.49 ftFPW = ~300 ftD50 = 0.57 mm (coarse sand)Stream Type = E5
Lewis Creek 4
8
10
12
14
16
18
20
0 5 10 15 20 25 30 35 40 45
Distance From Lef t Bank (f t)
Elevation (ft)
XS – 4RunWidth = 38 ftMax Depth = 3.6 ftFPW = ~300 ftD50 = 0.25 mm (medium sand)Stream Type = C5
Lewis Creek 5
6
8
10
12
14
16
0 10 20 30 40 50 60 70 80 90
Distance From Lef t Bank (f t)
Elevation (ft)
XS – 5RiffleWidth = 26.28 ftMax Depth = 4.25 ftFPW = ~300 ftD50 = 7.10 mm (fine gravel)Stream Type = E4
Valley slope = 0.46%(change in elevation of water surface /down valley length)(13.3 – 7.91 / 1170)
Channel Slope = 0.23%(change in elevation of water surface / channel length)(13.3 – 7.91 / 2348)
Lew is Creek
4
6
8
10
12
14
16
18
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Channel Distance (ft)
Elevation (ft)
thalweg water srf LB RB BKF XS
Channel Longitudinal Profile
Beaver damBeaver dam
Size percent less than (mm) Percent by substrate type
D16 D35 D50 D84 D95 silt/clay sand gravel cobble boulder bedrock
Particle Size (mm) Total 0.077 0.301 1.391 26.781 53.748 11% 41% 45% 3% 0% 0%Percent Finer Than Riffle 0.124 0.871 8.436 35.315 58.720 6% 31% 59% 4% 0% 0%
Pool
Run 0.067 0.138 0.750 17.492 50.776 14% 47% 37% 2% 0% 0%
Glide
Total Pebble Count
0%10%
20%
30%
40%50%
60%
70%80%
90%
100%
0.01 0.1 1 10 100 1000 10000
Particle Size (mm)
Percent Finer Than
Runs
Total
Riffles
Example of Prioritizing Reaches(in order of highest to lowest priority)
• Conservation Reaches- Least disturbed, river structure and vegetation intact
• Strategic Sites- Highly sensitive to disturbance, impacts may trigger off site response
• Reaches with High Recovery Potential- Possible self adjustment or minimal management efforts
• Moderate to Highly Degraded Sites- Require invasive management strategy
How the some of the Data from the Assessments has been used to date:
1) Assisting LCA with making recommendation to Town of Starksboro for their management plan of the Cota Farm property
2) Insuring that recreation path and potential structures are out of the flood plain and potential changes in the channels planform
3) Establishing cross-sections for long term monitoring. Ability to determine rate of change laterally and vertically along reach.
4) Providing the USFW with information on where habitat features and riparian planting may be needed
* Reach is a good candidate for a Passive Geomorphic Approach
Involves the removal of constraints from a river corridor thereby allowing the river, utilizing its own energy and watershed inputs to re-establish its meanders, floodplains, and self maintaining, sustainable equilibrium condition over an extended time period.
Active riparian buffer re-vegetation and long-term protection of a river corridor is essential to this alternative.