Rivers and Streams, Characteristics - Hydro-Environmental Analysis: Freshwater Environments - page 38

Structural
controls,
lithology

Fluvial
process

Depositional
materials

Climatic
influence

Broad life
zones

Basin relief Landforms Va lley morphology

Watershed

Drainage network

Geomorphic
characterization

Channel patterns:
Single thread
Multiple thread
Anastomosed
Sinuosity
Meander width ratio

Channel slope:
Valley slope/sinuosity

Level 1

Channel shape:
Narrow-deep
Wide-shallow

Stream types
“A” through “G”

Morphological
description

Entrenchment ratio
Width/depth ratio
Sinuosity

Channel slope
Channel materials

Level II

Stream types
A1-A6 through G1-G6

Bank erosion potential
Stream size/order
Flow regime
Altered channel “state”
... dimensions
... patterns
... slope
... materials

Riparian vegetation
Depostion pattern
Debris occurrence
Meander pattern
Channel stability rating
... sediment supply
... bed statbility
... width/depth ratio “state”

Stream “state” or
condition

Level III

Stability:
Aggradation/degradation

Sediment measurements:
Bed-load sediment
Suspended sediment

Sediment:
Change in storage and
size distribution
Bank erosion rates
Imbeddedness/distribution
Time trends-stability

Va lidation level
Level IV

Streameflow
measurements:
Hydraulics
Resistance
Hydrographs

FIGURE 2.25 Levels of the Rosgen classiication system. (From Harman, W.A. and Jennings, G.D.,
Application of the Rosgen stream classiication system to North Carolina, North Carolina State University,
North Carolina Cooperative Extension Service, Fact Sheet Number 2, 1999. With permission.)

2.2.4 V arIatIonS wItH t IMe
Rivers are, by their nature, dynamic systems or systems that change over time. Streams are constantly
changing their physical character (morphology), which, in turn, affects their ability to perform impor-
tant ecological functions (Fischenich et al. 2000). This is natural, even in streams that are “stable,”