LAR 512 – Fall 2002

 

PROBLEM #20 – BASIC STREAM CHANNEL CLASSIFICATION

 

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On the field trip to Lake Raleigh, we will investigate a reach of Walnut Creek below Lake Raleigh.  You will want to keep notes of your observations.  After return from the trip, compare you field notes to the Rosgen classification system and answer the following questions:

 

Reach Downstream of Lake Raleigh

  1. Using the Rosgen’s Level I Geomorphic Characterization: general description, landform, soils, and features decide which Stream Type (Aa+ through G) best represents this reach?  ____________ Table 4-1

 

  1. Now apply the Rosgen’s Level II Morphological Description criteria:

 

    1. Entrenchment Ratio = __________ (width of flood prone area at elevation twice maximum bankfull depth/bankfull depth),

 

    1. Width/depth Ratio =  __________ (ratio of bankfull/mean bankfull depth),

 

    1. Dominant Channel Materials =  __________ (D50 particle size in channel bed),

 

    1. Slope =  __________ percent,

 

    1. Bed Features =  _____________________ (descriptive channel configuration: riffle/pools, rapids, step/pools, cascades, and convergence/divergence features),

 

    1. Sinuosity =  __________ (stream length/valley length, or valley slope/channel slope),

 

    1. Meander Width Ratio =  __________ (meander belt width/bankfull width), and

 

    1. Now using Rosgen’s Level II Classification Key, determine the Stream Type __________  Figure 5-3
  1. Now apply the Rosgen’s Level III Assessment of Stream Condition and Departure criteria:

 

    1. Riparian Vegetation RV# __________ Table 6-1

 

    1. Streamflow Regime Category __________  Table 6-2

 

    1. Stream Size and Stream Order Category __________  Table 6-3

 

    1. Depositional Patterns Category __________  Table 6-4 and Figure 6-10

 

    1. Meander Patterns Category __________  Table 6-5 and Figure 6-12

 

    1. Organic Debris and/or Channel Blockage Category __________ Table 6-6

 

    1. Stream Channel Stability Points __________ and Rating __________ Table 6-7

 

    1. Degradation Category __________  Figure 19

 

    1. Aggradation Category __________  Figure 20