- List three common stream zones and describe their characteristics.
a. Headwaters – high potential energy, steep slope, narrow/shallow channel, high bedload, V-shaped valleys
b. Transfer zone – potential and kinetic energy nearly equal, resulting in more stable stream beds, medium slope, wider / deeper channel, suspended sediment
c. Depositional zone – potential energy is the lowest, sediment is deposited
- Diagram using different profiles of a stream the following features: riffles, runs, pools, glides, thalweg,
riffles- shallow w/ steep water surface
runs – deeper w/ less turbulent surface
pools – forms on outside bend, along banks, behind boulders. Water moves slower, deposition
glides – transition from pool to riffle
thalweg – Deepest part of the river. Created by focused erosion from increased velocity
- How does pool-riffle sequences and the meandering of the stream channel influence the energy of the stream? (answered over multiple slides)
a. it helps to dissipate kinetic energy
- How frequent do rivers reach their bankful width and how does this correlate with the flood plain?
a. about every 1-2 years. Once the bankful width is exceeded, the water inundates the flood plain
PFC of riparian floodplains exists when adequate vegetation, landform, or large debris is present to ________.
a. reduce erosion
b. trap sediment
c. build/enlarge the floodplain
- Describe separately using Lane’s Balance what a river will do as a result of sediment amount, water amount, channel slope, and sediment size
Overgrazing, Dewatering, Mud slide into stream
a. Overgrazing in a watershed – increased water and therefore erosion initially, to correct the river would increase in sinuosity decreasing the slope and restoring Lane’s balance
b. Dewatering of a stream from a diversion – Initial loss of water will cause increased deposition, until the steepness of the channel slope increases to correct
c. Mud slide into a stream – initial increase in sediment causes the balance to switch to deposition. Corrects by increasing channel slope by reducing meandoring
The units for stream discharge are 〖ft〗^3⁄sec . Describe how those units are achieved.
- You take a section of the river and multiply width (ft) x height (ft) = ft^2
- multiply ft^2 by velocity (ft/s), and you have cubic feet / second
- You can find the depth and flow of each subsection, and fine the average to get a measure of discharge
- Describe seven different ways for measuring stream flow.
- With a current meter – use the method described above
- float method – time the distance it takes for an object to flow a known difference
- dilution gauge – often applied to turbulent streams. Tracer (a salt) added to stream, and a reader detects the change in electro-conductivity
- stream gauge station – measures height of a stream and estimates flow from a rating curve. Height determined by a pressure gauge
- Bucket and stopwatch method – temporarily dam water so it goes through a pipe, place a container of known volume under pipe, using a stopwatch, time how long it takes to fill the container, repeat 3x to obtain an average
- flume – channels all the water through. Using the height and the known dimensions, you can determine stream flow
- Weirs – a weir will backup the water like a dam. Otherwise identical to the flume method
- Contrast the hydrographs of a snow-dominated system compared to a rain-dominated system.
- Snow dominated has a rising limb in April/May
- rain dominated has several peaks that may be continuous over more of the year
- What is the difference between a perennial, intermittent, and ephemeral stream? As part of your answer define their relationship with ground water.
perennial – maintains flow during dry and wet seasons, flows at least most of the year. Connected with water table
Intermittent – only flows during wet season. Close to water table when table is high
Ephemeral – rarely flows (regardless of season). Almost always above water table
- Write the calculation for stream: entrenchment ratio, sinuosity
c. Entrenchment ratio – Flood prone width / Bankfull width. Ratio of 1.0 means the floodprone width = bankful width
f. Sinuosity – channel length / valley length. A ratio that tells us how curvy a river is
- What is the Wolman Pebble Count used for?
- Helps you determine the main substrate material in your stream
Briefly describe after reading the notes section in the presentation what an Aa+, A, B, C, D, DA, E, F, and G streams are.
Aa+ - Occurs on very steep gradients. Naturally entrenched. Narrow and deep with little meandering.
A – Occurs on 4-10% slopes. Multiple step/pools. Low sediment storage capacity, high sediment transport capacity.
B – Occur on moderately steep to gently sloped terrain. Moderately entrenched. Wider and shallower than A type. Rapids dominated bed morphology
C – Slightly entrenched with well developed floodplain. Relatively sinuous with a channel slope of 2% or less. Point bars are common.
D – Multi-channel stream where stream channels are highly unstable and shift frequently. Very wide and shallow.
DA – Multi-channel stream where stream channels are relatively stable, stabilized by vegetation. Extremely gentle channel slopes, commonly at or less than .0001
E – Highest sinuosity. Developmental “end-poiint” of channel stability. Often develops from the “F” stream types. Narrow and deep (low width/depth ratio).
F – Entrenched and meandering, working towards re-establishment of a functional floodplain within the confines of a channel that is consistently increasing its width within the valley. High width/depth ratio.
G – G or „Gully“ stream type. Entrenched, narrow and deep step/pool channel with a moderate to low sinuosity. High bank erosion rates and high sediment supply.
- What does PFC stand for
Proper Functioning Condition
- Define these terms – riparian, wetland, lentic, lotic
a. Riparian – an area of land directly influenced by permanent water. Visible in vegetative and physical characteristics reflective of permanent water influence.
b. Wetland – Areas with “hydric” soils that are permanently or seasonally saturated by water
c. Lentic – aquatic system with standing water
d. Lotic – aquatic system with moving water
- PFC exists when adequate vegetation, landform, or woody vegetation is present to (list 7 reasons):
- dissipate stream energy
- stabilize banks
- reduce erosion
- trap sediment
- build/enlarge floodplain
- store water (works as a sponge)
o Retain floodwater
o Recharge groundwater
o Sustain baseflow
- List and describe 7 values that are provided from a riparian system that has the values in question #5.
a. water quality
b. water quantity
c. forage production and quality
d. aquatic habitat
e. wildlife habitat
f. recreational value
g. aesthetic beauty
- Why would a livestock producer want to preserve riparian areas for their livestock (give 8 reasons)?
- highly productive
- high quality (especially valuable in late summer)
- access to water
- lower temperatures in the summer (shade)
- increases wildlife habitat
- improves fisheries
- preserves soil resources
- increases water quality
- increases duration of water
- longer grazing season
- Describe the six stages of stream evolution.
a. Stage 1: High degree of stability, floodplain development, and plant community development (similar to reference state)
b. Stage 2: Down-cutting in the channel, disconnect between the water table and the vegetation
c. Stage 3: Stream channel is incising to a new base level, bank-stabilizing vegetation is sparse/absent, and high streamflows cannot/rarely access the floodplain
d. Stage 4: The channel continues widening, which allows flow energies to decrease.
e. Stage 5: Active floodplain reestablished, but at a lower-level w/ sagebrush meadow present. PFC or FAR
f. Stage 6: floodplain starts filling back in, moving towards stage 1. PFC
- Outline the six assessment items for describing PFC and their respective purposes
a. Item 1: Floodplain is inundated in relatively frequent events
b. Item 2: Beaver dams are stable
c. Item 3: Sinuosity, gradient, and width/depth ratio are in balance with the landscape setting
d. Item 4: Riparian area is expanding or has achieved potential extent
e. Item 5: Riparian impairment from upstream or upland watershed is absent
f. Item 6: There is adequate diversity of stabilizing vegetation for recovery / maintenance
g. Item 7: There are adequate age classes of stabilizing riparian vegetation for recovery/maintenance
h. Item 8: Species present indicate maintenance of riparian soil moisture characteristics
i. Item 9: Stabilizing plant communities capable of withstanding moderately high streamflow events are present along the streambank
j. Item 10: Riparian plants exhibit high vigor
k. Item 11: Adequate amount of stabilizing riparian vegetation is present to protect banks and dissipate energy during moderately high flows
l. Item 12: Plant communities are adequate source of woody material for maintenance / recovery
m. Item 13: Floodplain and channel characteristics (i.e. rocks, woody material, vegetation, floodplain size, overflow channels) are adequate to dissipate energy
n. Item 14: Point bars are revegetating with stabilizing riparian plants
o. Item 15: Streambanks are laterally stable
p. Item 16: Stream system is vertically stable (not incising)
q. Item 17: Stream is in balance with the water and sediment that is being supplied by the drainage basin (no excessive erosion or deposition
- Why would a livestock producer want to preserve riparian areas for their livestock (give 8 reasons)?
- highly productive
- high quality (especially valuable in late summer)
- access to water
- lower temperatures in the summer (shade)
- increases wildlife habitat
- improves fisheries
- preserves soil resources
- increases water quality
- increases duration of water
- longer grazing season
