Substrate

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Stream Ecosystems
Watersheds to Reaches
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Sample Reach
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Hydrologic Cycle
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Contributing Area Watershed
A watershed is defined as an area of land that
drains water, sediment, and dissolved materials
to a common outlet at some point along a stream
channel (Dunne and Leopold 1978).
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Watersheds
Occur at multiple scales Watersheds range from
the largest river basins, with watersheds
thousands of acres in size to small streams,
with watersheds measuring only a few acres in size
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Delineating Your Watershed
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Large Scale Factors to Consider
LATITUDE
ALBEDO
CLIMATE
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Watershed Characteristics
Slope Aspect Shape
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Watershed Characteristics
Land Cover Surface Roughness
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Watershed Characteristics
Soil Characteristics
texture structure moisture
Permeable High infiltration
Impermeable clay High surface runoff
Large Macropores High Infiltration
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Cumulative Effects
Land Management Throughout Your Watershed Can
Have Impacts Downstream
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Measuring Physical Characteristics

• What is the function of a stream?
• What data reflect a streams ability to
  function?
• How can the physical data and stream function
  be summarized in a useful way?

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Stream Function

• To move water

Each stream balances erosion, transport, and
deposition in the context of its climate and
landscape.

• To move sediment

A Stream is a Transport Machine
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Streams as Transport Machines
Some independent variables, functions of the
watershed influence the streams ability to
function as a transport machine Elevations,
Elevation Change Sediment load Discharge
(flow) Bankfull flow (channel forming) Flood
flow (floodplain)
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Balancing Water and Sediment
Qs . D50 in balance with Qw . S Qs
sediment load Qw stream discharge D50
sediment size S stream slope
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Stream Reach Characteristics
Stream Channel - a channel with flowing water at
least part of the year. Bankfull stage of
water which maintains channels (1.5-2 year
recurrence interval) Floodplain - a highly
variable area on one or both sides of the stream
channel that is inundated by floodwaters at some
interval, from frequent to rare. Terraces
remnants of historic floodplains
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Indicators of Floodplain/Terraces
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Collecting Data on Stream Function
When gathering data, choose parameters that
reflect the streams ability to function as a
transport machine Bankfull Characteristics Flo
odplain Characteristics Sediment
Characteristics Stream Bank Characteristics
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Physical Characteristics
Channel Dimension map cross-sections Bankfull
width Mean bankfull depth Bankfull
cross-sectional area Width depth
ratio Maximum depth Channel Pattern use aerial
photos Sinuosity Channel Profile map
longitudinal profiles Bankfull, water surface
and channel slopes
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Physical Characteristics
Floodplain Characteristics Floodprone
width Entrenchment ratio (bankfull width
floodprone width) Sediment Load
Characteristics D-50 D-84 Bar samples Stream
Bank Characteristics Field observation
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Bankfull Stage
The bankfull stage corresponds to the discharge
at which channel maintenance is the most
effective, that is, the discharge at which moving
sediment, forming or removing bars, forming or
changing bends and meanders, and generally doing
work that results in the average morphological
characteristics of the channel.
Water in Environmental Planning, T. Dunne and
L.B. Leopold, W.H. Freeman and Co., San
Francisco, CA, 1978
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Bankfull Flow
1.5-2 year recurrence interval
Bankfull Flow
Baseflow
Big Goose Creek near Sheridan, Wyoming
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Indicators of Bankfull Stage

• The height of depositional features (especially
  the top of the pointbar, which defines the
  lowest possible level for bankfull stage)
• A change in vegetation
• Slope or topographic breaks along the bank

• A change in the particle size of bank material,
  such as the boundary between coarse cobble or
  gravel with fine-grained sand or silt
• Undercuts the bank, which usually reach an
  interior elevation slightly below bankfull stage
• Stain lines or the lower extent of lichens on
  boulders

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Cross Section Measurements
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Physical Characteristics
Channel Dimension map cross-sections Bankfull
width Mean bankfull depth Bankfull
cross-sectional area Width depth
ratio Maximum depth Channel Pattern use aerial
photos Sinuosity Channel Profile map
longitudinal profiles Bankfull, water surface
and channel slopes
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WidthDepth Ratio
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Physical Characteristics
Channel Dimension map cross-sections Bankfull
width Mean bankfull depth Bankfull
cross-sectional area Width depth
ratio Maximum depth Channel Pattern use aerial
photos Sinuosity Channel Profile map
longitudinal profiles Bankfull, water surface
and channel slopes
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Sinuosity
River Distance Straight Line Distance
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Sinuosity
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Physical Characteristics
Channel Dimension map cross-sections Bankfull
width Mean bankfull depth Bankfull
cross-sectional area Width depth
ratio Maximum depth Channel Pattern use aerial
photos Sinuosity Channel Profile map
longitudinal profiles Bankfull, water surface
and channel slopes
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Water Surface Slope
Rise/Run
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Physical Parameters
Floodplain Characteristics Floodprone
width Entrenchment ratio (bankfull width
floodprone width) Sediment Load
Characteristics D-50 D-84 Bar samples Stream
Bank Characteristics Field observation
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Floodprone Width
Width Where Stage is 2X Bankfull Max Depth
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Physical Parameters
Floodplain Characteristics Floodprone
width Entrenchment ratio (bankfull width
floodprone width) Sediment Load
Characteristics D-50 D-84 Bar samples Stream
Bank Characteristics Field observation
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Entrenchment Ratio
Flood Prone Width/Bankfull Width
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Entrenchment Ratio
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Physical Parameters
Floodplain Characteristics Floodprone
width Entrenchment ratio (bankfull width
floodprone width) Sediment Load
Characteristics D-50 D-84 Bar samples Stream
Bank Characteristics Field observation
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Sediment Characteristics
Boulder gt 256 mm Cobble 64-256
mm Pebble 16-64 mm Gravel 2-16
mm Sand 0.0625-2 mm Silt 0.0039-0.0625
mm Clay lt0.0039 mm
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Quantitative Description of Stream Function
These parameters are the basic delineative
criteria needed to quantitatively describe a
streams function and begin assessment if can
organize data in useful system Rosgen Channel
Classification
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Stream Classification
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Rosgen Stream Classification
Rosgen classification scheme initially sorts
streams into the major, broad stream types (A-G)
at a landscape level A-headwater B-intermediate C
and E-meandering D-braided F-entrenched G-gully
Stream types are divided into subtypes based on
slope ranges, and dominant channel material
particle sizes. 1-bedrock 2-boulder 3-cobble 4-gr
avel 5-sand 6-silt/clay
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Rosgen Stream Classification
Applied River Morphology, Dave Rosgen, Wildland
Hydrology, Fort Collins, Colorado, 1996.
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Rosgen Stream Classification
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Why Establish Reference Sites?
Establishes a baseline for a broad range of
physical, chemical and biological monitoring.
Monitor trends in fluvial and geomorphic
conditions over time Quantify environmental
impacts Assess stream and watershed response to
management Provide channel and flow facts for
water allocation Support resource inventories
(habitat, water quality, vegetation) Track
cumulative effects for entire drainage
areas Contributing to regional, state, national
and international databases
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Site Selection
Ask the following questions What do we want to
know about this stream or drainage? What
variations (geology, elevation, land use) exist
in the area? How can we set up the most useful
comparisons with the fewest sites? How can this
site contribute to the existing or planned
efforts? How much can be accomplished with
present resources?
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Site Selection

• Choose sites with evident natural
  features-floodplains, terraces, bars and natural
  vegetation
• Reach should include an entire meander length
  (two bends) if possible. The length should be at
  least 20 times bankfull width of the channel.
• Unless your purpose includes studies of beaver
  dams, debris jams, boulder fields, bedrock
  controls, and recently adjusted channels (flood,
  disturbance), select your site to avoid such
  features

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Natural stream channel stability is. Stable
dimension, pattern, and profile such that, over
time, the channel features are maintained and the
stream system neither aggrades nor degrades for
a given climate.
Applied River Morphology, Dave Rosgen, Wildland
Hydrology, Pagosa Springs, Colorado, 1996.
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Major Sub-Basins of Wyoming