ENSC 202 2004 - PowerPoint PPT Presentation

1 / 18
About This Presentation
Title:

ENSC 202 2004

Description:

Extracted from Vermont ANR Stream Geomorphic Assessment Protocols ... GIS, planimeter, or graph paper methods. Step 2.8 Reference channel width (provisional) ... – PowerPoint PPT presentation

Number of Views:46
Avg rating:3.0/5.0
Slides: 19
Provided by: BreckB7
Learn more at: https://site.uvm.edu
Category:
Tags: ensc | planimeter

less

Transcript and Presenter's Notes

Title: ENSC 202 2004


1
Watershed Assessment (ENSC 202)
  • Phase 1 Steps 2-5
  • Extracted from Vermont ANR Stream Geomorphic
    Assessment Protocols Handbook - Introduction

2
Step 2 Determining Stream Types
  • 2.1 Downstream and Upstream Elevations
  • 2.2 Valley Length
  • 2.3 Valley Slope
  • 2.4 Channel Length
  • 2.5 Channel Slope
  • 2.6 Sinuosity
  • 2.7 Watershed Size
  • 2.8 Channel Width
  • 2.9 Valley Width
  • 2.10 Confinement
  • 2.11 Stream Type

3
Notes on Step 2
  • This is a first cut only, dont sweat it.
  • Focus is on what the reach might be like in the
    absence of human influences a true reference.
  • Be consistent in how you make each measurement.
  • Be consistent with your measurement units.
  • Potential measuring tools ruler, map wheel, GPS
    mapping tools, GIS

4
  • Step 2.1 Downstream Upstream elevations
  • Point at which contour crosses stream
  • Interpolate between contours
  • Step 2.2 Valley length
  • Straight line distance between reach breaks
  • Follow tendency (valley walls) not meanders
  • Step 2.3 Valley slope
  • (change in elevation/valley length)100
  • Step 2.4 Channel length
  • Actual channel (thalweg) distance
  • Note difference from Valley Length (2.2)
  • Step 2.5 Channel slope
  • (change in elevation/channel length)100
  • Step 2.6 Sinuosity
  • Channel length/valley length

5
  • Step 2.7 Watershed size
  • Drainage area above downstream reach break for
    each reach
  • GIS, planimeter, or graph paper methods
  • Step 2.8 Reference channel width (provisional)
  • Based on regional hydrologic geometry
  • Limitations mid-to-large sized streams in
    unconfined, moderate-to-gentle gradient, alluvial
    settings
  • Make best guesses now, you can adjust this later
    with field data from confirmed reference
    reaches
  • Step 2.9 Valley width
  • Measure width between the first lateral contours
    next to the stream (hard in confined valleys)
  • Make 10 measurements per reach/valley and
    average

6
Vermont RegionalGeometry Curves
95 confidence intervals
7
  • Step 2.10 Confinement (provisional)
  • (valley width/channel width) 2.9/2.8
  • Step 2.11 Reference stream type (Appendix I)
  • Based on Rosgen (1996) and Montgomery
    Buffington (1997)

8
Step 3 Basin Characteristics Geology and Soils
  • 3.1 Alluvial Fan
  • 3.2 Grade Controls
  • 3.3 Geologic Materials
  • 3.4 Valley Side Slopes
  • 3.5 Soil Characteristics

9
  • Step 3.1 Alluvial Fans (Y/N)

10
  • Step 3.2 Grade controls
  • Step 3.3 Geologic materials

NRCS Top 20 soils (?)
Defining channel corridor (Appendix E)
11
  • Step 3.4 Valley side slope
  • Directly from topo maps
  • Step 3.5 Soil characteristics
  • Hydrologic Group
  • Flooding
  • Water Table
  • Erodibility

12
Step 4 Land Cover and Reach Hydrology
  • 4.1 Watershed Land Cover / Land Use
  • 4.2 Corridor Land Cover / Land Use
  • 4.3 Riparian Buffer Width
  • 4.4 Groundwater and Small Tributary Inputs

General characterizations based on observations
of older and more current maps, orthophotographs,
existing data, or windshield surveys.
13
  • Step 4.1 Watershed Land Cover and Land Use
  • Current best available
  • Historic 1970s orthophotos
  • Assign impact rating
  • Step 4.2 Corridor Land Cover and Land Use
  • Current best available
  • Historic 1970s orthophotos
  • Assign impact rating

14
  • Step 4.3 Riparian buffer widths
  • left vs right bank
  • Record dominant buffer width by bank
  • Note particular restoration opportunities
  • Step 4.4 Groundwater small tributray inputs
    (wetlands)
  • No impact rating?

15
Step 5 In-stream Channel Modifications
  • 5.1 Flow Regulations and Water Withdrawals
  • 5.2 Bridges Culverts
  • 5.3 Bank Armoring or Revetments
  • 5.4 Channel Modifications
  • 5.5 Dredging and Gravel Mining History

16
  • Step 5.1 Flow regulation and water withdrawals
  • Consult with DEC, town records, utilities
  • Step 5.2 Bridges and culverts
  • Count number
  • Will probably have to be augmented with
    windshield surveys

17
  • Step 5.3 Bank armoring and revetments
  • Will probably have to be augmented with
    windshield surveys
  • armoring (RB armor length LB armor length
    overlap)
  • (total RBRL length)

18
  • Step 5.4 Channel modifications
  • Will probably have to be augmented with
    windshield surveys
  • Step 5.5 Dredging and gravel mining history
  • DEC Stream Alteration Engineers, town records,
    road commissioners
  • Will probably have to be augmented with
    windshield surveys
Write a Comment
User Comments (0)
About PowerShow.com