1 / 64

Natural Riparian Resources

Natural Riparian Resources. Water. Landscape & Soil. Vegetation. Stream Channels Must:. Be able to access a floodplain Maintain the water table Transport the natural sediment load. The stream does this by maintaining the appropriate:. Channel Dimensions ( width/depth ratio )

urvi
Download Presentation

Natural Riparian Resources

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Natural Riparian Resources Water Landscape & Soil Vegetation

  2. Stream Channels Must: • Be able to access a floodplain • Maintain the water table • Transport the natural sediment load

  3. The stream does this by maintaining the appropriate: • Channel Dimensions(width/depth ratio) • Meander Pattern (sinuosity) • Profile (gradient or slope) THEY ARE ALL INTERRELATED!!

  4. Rosgen Stream ClassificationWidth/Depth Ratio

  5. Rosgen Stream Classification Sinuosity Sinuosity = Stream Length/ Valley Length 1.9 370’ 195’

  6. Rosgen Stream ClassificationSinuosity Sinuosity = Stream Length / Valley Bottom Length 1 = 100’ / 100’

  7. Rosgen Stream ClassificationSlope or Gradient Elevation at Elevation at upper end - lower end % Mean Slope = * 100 Stream channel length

  8. Rosgen Stream ClassificationEntrenchment Ratio

  9. Change channel shape = change functionalityDixie Creek, Nevada W/D ratio = 9.3 W/D ratio = 40 30 cfs 30 cfs

  10. Change channel shape = change functionalityBox Elder Creek – Black Hills W/D ratio = 1.5 W/D ratio = 8.0 8 cfs 8 cfs

  11. Stream Classification • Ordering of streams into sets based on their similarities or relationships • Objectives • Predict river’s behavior • Provides hydraulic and sediment relationships • Extrapolate site specific data to similar streams • Consistent framework for communication

  12. Rosgen Stream Classification • Stream Characterization • Channel Characteristics • Width to Depth Ratio • Entrenchment Ratio • Channel Material

  13. Rosgen Stream Types Rosgen, 1996

  14. Type Aa+

  15. Type A

  16. Type B

  17. Type C

  18. Type DA

  19. Type D

  20. Type E

  21. Type F

  22. Type G

  23. Rosgen Stream ClassificationChannel Material (substrate) • 1 – Bedrock • 2 – Boulder (10+ inches) • 3 – Cobble (2.5 to 10 inches) • 4 – Gravel (.08 to 2.5 inches) • 5 – Sand (.062 to 2 millimeters) • 6 – Silt/Clay (< .062 millimeters)

  24. Standard Checklist (lotic)

  25. 1) Floodplain above bankfull is inundated in “relatively frequent” events • Purpose: To determine if frequent floodflows are capable of spreading out on a low-lying area adjacent to the stream. • Item is NA if floodplains are not a feature of the stream type • Look for indicators such as oversized channel, incised channel, upstream reservoir • Many spring fed streams in small watersheds lack well defined floodplains

  26. Terrace Bankfull Floodplain

  27. Floodplain Terrace Terrace Floodplain • Level area near a stream channel • Constructed by the stream • In the present climate • Flooded during moderate events • Should not be confused with “terraces” (abandoned floodplains) 1994 Leopold

  28. Discharge at bankfull stage creates & maintains channels Moves sediment Forms or removes bars Forms or changes bends and meanders Results in the average geomorphologic channel characteristics Recurs every 1 to 2 years

  29. Bankfull Indicators • Deposition Features • Top of point bars • Change in Vegetation • Especially lower limit of continual line of perennial species, at least 1 ft.

  30. Bankfull Indicator Top of Point Bars

  31. Bankfull Indicators • Change in particle size of bank material • Boundary between cobble/boulder and fine grained sand or silt • Undercut banks • Usually slightly below bankfull stage • Stain lines or lower extent of lichens on boulders (Usually in large rivers)

  32. Should this stream type have a floodplain? • How wide should it be? • How wide is it? • Is the stream channel incised or over sized? • Has widening begun? • Are most terrace walls sloped indicating widening has stopped? • Is there an up stream reservoir?

  33. Should this stream type have a floodplain? • How wide should it be? • How wide is it? • Is the stream channel incised or over sized? • Has widening begun? • Are most terrace walls sloped indicating widening has stopped? • Is there an up stream reservoir?

  34. 2) Where beaver dams are present, they are active and stable • Purpose: To document whether beaver are present, and if so, whether the dams are being maintained. • Beaver must be present or the dam is causing hydrologic effects • If dams are present then stability must be addressed • Usually a single dam is subject to high storm events

  35. Are beaver dams currently acting as hydrologic modifiers? • Are beaver present? • Are beaver actively maintaining the dam? • Is there sufficient food to support the beaver? • Is the dam self-sustaining, e.g., significant vegetation is rooted in the dam? • Is the beaver dam a single large dam? • Are the beaver dams in a complex?

  36. No – not active and unstable

  37. Yes, both active and stable

  38. 1995 1992

  39. 3) Sinuosity, width/depth ratio, and gradient are in balance with the landscape setting (i.e., landform, geology, and bioclimatic region) • Purpose: To determine if the stream has the appropriate dimension, pattern, and profile for the setting. Item has three parts: • Sinuosity • Width/Depth ratio • Gradient • All three must be “yes” for the answer to be “yes” • Undercut/overhanging banks indicator of a “yes”

  40. Sinuosity • Is the stream actively eroding and building point bars? • Are there indications of channel straightening? • Does the sinuosity appear to be appropriate for the valley bottom type?

  41. Sinuosity • Is the stream actively eroding and building point bars? • Are there indications of channel straightening? • Does the sinuosity appear to be appropriate for the valley bottom type?

  42. Width/Depth Ratio

  43. “most streams cross-section are not parabolic or semicircular (dish-shaped) in shape along the straighter reaches” Leopold 1994 “Rather, they are usually trapezoidal in shape with distinctly developed streambanks” Leopold 1994

  44. Width/Depth Ratio – Over-widened channel indicators • Bank slumping and shearing • Woody species growing within the channel • Dish-shaped banks

  45. Width/DepthRatio • Is the stream channel dish-shaped? • Are streambanks slumping? • Is the floodplain the appropriate size (see question 1)?

  46. Gradient (closely related to sinuosity) • Is the channel incised or overwidened? • Does the channel appear to be straightened? Decreased sinuosity = Increase gradient • Does the sinuosity appear to be appropriate for the valley bottom type?

  47. Is the channel incised or overwidened? • Does the channel appear to be straightened? • Does the sinuosity appear to be appropriate for the valley bottom type?

More Related