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Lewis Creek Reach M19

Lewis Creek Reach M19. Phase 1, Phase 2, and Phase 3. M19. Lewis Creek Watershed. Phases of Assessment. Phase 1 - Remote Sensing and Existing Data Phase 2 - Qualitative and Rapid Field Assessment Phase 3 - Field Survey Assessment Watershed Reach

carlos-cervantes
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Lewis Creek Reach M19

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  1. Lewis Creek Reach M19 Phase 1, Phase 2, and Phase 3

  2. M19 Lewis Creek Watershed

  3. 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

  4. Topographic lines overlaid on Orthos Local Knowledge and NRCS Information • Channelization upstream of farm bridge occurred in 60’s • Rip-rap routinely installed since at least early 80’s • Current farm bridge moved to new location in 1981 • Past landowners did channel “work” to maintain straighter channel • High floods in the late 1980’s • Out of bank flows occur about every 2 years, flashy events every year • Entire valley bottom has been flooded in past • Soil cores done on Lewis Creek Farm confirm presence of glacial lake clays in valley bottom • Bank re-vegetation projects occurred in 1990’s on Lewis Creek Farm

  5. Topographic Map Comparison 1905 1983

  6. Orthophoto Comparison 1942 1995

  7. Changes in Planform 1983 Topographic Map

  8. Phase 1 River Corridor (Corridor is approx 475 ft wide at ball field area and approx 375 ft wide along the remainder of the reach) Parameters evaluated in Phase 1 Corridor • Soils and Geology • Land Use and Land Cover • Riparian Vegetation • Berms, Roads & Improved Paths • Development

  9. Approximate valley wall Soils Data and approximate Valley Wall Lines Corridor where soils reviewed

  10. Various types of soil parameters that can be evaluated using the soil maps. Flood Potential Slope Types Parent Material

  11. 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: • Active Agriculture in corridor (crop) {Step 4} • Little to no Riparian vegetation {Step 4} • Channel modification (straightening) {Step 5} • Bank Armoring (Rock rip-rap) {Step 5} • Mid-channel bars {Step 6} • Planform changes (meander migration & avulsions) {Step 6} • Erosion {Step 7}

  12. 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

  13. Geomorphic and Habitat Assessment Assessment 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

  14. 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

  15. Measuring channel data: • Width • Depth • Flood Prone Width • Entrenchment • Evaluating: • Bank Vegetation • Riparian Vegetation • Corridor Land Use

  16. 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

  17. Noting: • Bank Erosion and Scour • Bank Slope • Recording Types of Bank Protection: • Rip-rap • Tree revetments

  18. Fines Small gravels Comparison of upper and lower bank material • Sediment types seen along reach: • Gravels • Sands • Clays and silts

  19. Evaluating types of bed sediment storage seen: • Mid-channel bars • Point bars • Diagonal Bars

  20. BD BD Beaver Activity May Affect Stream by: • Changing water levels • Altering Sediment deposition locations • Influencing planform changes • Creating or changing habitat features

  21. Reach Number Segment Habitat Condition Geomorphic Condition Dominant Adjustment Process Concurrent Adjustment Process Stage of Channel Evolution * Channel Sensitivity to Disturbance Flood-prone Width (ft) Low Bank Height (ft) Stream Bed Feature Type Stream Type Bed Material Bankfull Width (ft) Max Depth (ft) Channel Slope (Phase1) Reach Number Entrench-ment Width/ Depth Ratio Stream Type Incision Ratio Segment Sinuosity M19 A Poor Poor Widening Aggredation Widening –III /IV very high to extreme Riffle-Pool M19 A 40 500 3 - 4.5 18.7 Moderate 0.40% - C 4 *M19 B Fair Fair Aggredation Widening Widening –III /IV very high to extreme Riffle-Pool *M19 B 69 500 4 - 7.2 24.4 Moderate 0.40% - C 4

  22. Some of the things that affected the habitat were: • 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: • 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

  23. Phase 3 , Survey Level Assessment • Further verify the stream type. • Establish cross-sections for long term monitoring • Evaluate sediment size being transported by stream

  24. Flood History From Gage Records

  25. Bankfull stage flows in spring of 2002

  26. Bankfull stage flows in spring of 2002

  27. XS 5 XS 2 XS 1 XS 4 XS 3 Channel Planform and Cross-section Location 5 Monumented Cross-sections established

  28. Measuring Bankfull and Flood-prone Width Flood-prone elevation Bankfull elevation

  29. XS –1 Riffle Width = 33 ft Max Depth = 3.45 ft FPW = ~150 ft D50 = 10.66 mm (medium gravel) Stream Type = C4

  30. XS –2 Run Width = 31.74 ft Max Depth = 4.03 ft FPW = ~200 ft D50 = 1.34 mm (very coarse sand) Stream Type = E5

  31. XS – 3 Run Width = 27.49 ft Max Depth = 3.49 ft FPW = ~300 ft D50 = 0.57 mm (coarse sand) Stream Type = E5

  32. XS – 4 Run Width = 38 ft Max Depth = 3.6 ft FPW = ~300 ft D50 = 0.25 mm (medium sand) Stream Type = C5

  33. XS – 5 Riffle Width = 26.28 ft Max Depth = 4.25 ft FPW = ~300 ft D50 = 7.10 mm (fine gravel) Stream Type = E4

  34. Channel Longitudinal Profile Beaver dam Beaver dam 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)

  35. Runs Total Riffles

  36. 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

  37. How the some of the Data from the Assessments has been used to date: • 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

  38. * 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.

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