energy derived from organic matter produced outside the wetted stream channel
What is autochthonous energy?
energy produced within the wetted stream channel
What is a modern version of Playfair's Law?
The way the river looks comes from the fluvial processes; template driven
What are the watershed drainage patterns? What are the two most common watershed drainage patterns?
Two most common: dendritic and parallel Others: Trellis, Rectangular, Radial, Annual, Multi-Basinal, and Contorted
What are the three categories of streams?
Ephemeral - dry, flows less than 30 days per year Intermittent - wet, flows for more than 30 days Perennial - continuous influx of streamflow
How does surface and groundwater interact?
Effluent streams: input of water from the water table (perennial) Influent stream: outflow of water from the stream
Why is stream order important? What does it ignore?
Useful descriptor of the stream position within a basin Ignores the entry of low-order streams into higher-order streams
Why is the link classification system not always accurate?
Lose universality. Someone's 14 order may be another's 14 order
What is stream power? What is the equation for stream power? When does it peak?
accounts for ability of stream to change its channel, move rocks, etc stream slope x Discharge (amount of water) tends to peak in streams of mid-size where there is the most disturbance
What are the longitudinal profile zones?
Zone 1: Headwater streams Zone 2: Transfer zone Zone 3: Depositional zone
What is the headwaters zone?
Area where streams flow swiftly down steep slops and cut a deep V shaped valley. Rapids and waterfalls are common.
What is the transfer zone?
Low-elevation streams merge and flow down gentler slopes. The valley broadens and the river begins to meander.
What is the depositional zone?
At an even lower elevation, water wanders and meanders slowly across a broad, nearly flat valley. At its mouth it may divide into many separate channels
What is a degradational stream?
One in which is actively eroding
What is a aggradational stream?
One in which is full of alluvium or stored soil
What is a balanced stream?
degradation and aggradation is in a balance. The stream power is maximized
What are the characteristics of a Cascade reach?
boulder valley confined pool limited
What are the characteristics of a Step-pool reach?
cobble/boulder valley confined pools frequent
What are the characteristics of Pool-riffle reach?
gravel valley less confined pools spaced regularly found in zone 2
What are the characteristics of Dune-ripple reaches?
common for large and sandbed streams not seen often because covered by water hard to know where they are
What is the thalweg line?
path through a stream channel where most of the water passes
When do riffles occur?
when streams pass from one bank to the other
What is flow reversal?
When baseflow riffles have faster velocity than pools
What is low gradient stream closely linked to?
What does the sinuosity ratio tell us?
How sinuous a stream is EQ: length of the real channel/length of the hypothetical straight channel about 1: straight 1-1.5: sinuous >1.5: meandering
Why do streams meander?
velocity and energy
What happens to a stream that is meandering more and more?
going to go towards more and more meandering until part of the stream cuts off and forms an oxbow law (shape of a horseshoe)
What are different channel forms?
Single-tread Braided (rivers braid itself through floodplain)
What is the flood-pulse concept?
Idea that for many of these large floodplain rivers (zone 3), they have these floodplains because of flooding.
What have humans done to floodplains?
Tended to decouple flood pulse phenomenon so that channel is broken up and dries out
What is a levee?
piles of earth/stone along banks made to increase capacity of water stored in main channel to stop floods from escaping the channel
What are waterfalls important for?
zoogeographic barriers: provide isolation for biota
How do beavers modify streams?
Create habitats which change hydrology of stream and evolution of biota
What is the most important thing that distinguishes a stream (what controls what a stream looks like)?
Due to the physical things in nature
What affects stream temperature?
Incoming: Solar radiation, groundwater flux Incoming/Outgoing: Longwave radiation, air convection, evaporation/condensation, streambed conduction, hypoheic flux
What is the difference between streamwater and groundwater temperature?
Groundwater temperature is cooler and stable
What is the most important heat source in large rivers and lakes?
What is the most important heat source for shaded stream?
groundwater, but not ALWAYS more important
What does temperature regulate in streams?
Biotic metabolisms Chemical reaction rates
What happens to O2 as temperature increases?
Consumption of O2 increases in macroinvertebrates and fish because the warmer it gets, the more oxygen it needs
What are the thermal ranges in which an organism can live?
Stenothermal species: occupy a narrow range of temperature Eurythermal species: occypy a wide range of temperature
What is thermal optima?
Whether a species is coldwater, coolwater, or warmwater species
Why is there a low temperature change in headwaters and high order streams?
headwaters: buggered by springs and shade high order: tempered by large volume
What is the spatial temperature change in streams
Back water areas >> temperature than thalweg which provides opportunities for biota needing warmer temperature
What are the characteristics of temporal temperature change?
Seasons act as an indicated to development and synchronize life cycles
How does light varies in canopied streams?
What is the River Continunuum concept?
Photosynthesis/respiration is < 1 or >1
How does substrate embeddedness vary?
Space between rocks decresses with embeddedness
What do the space between rocks provide?
habitat for benthic macro-invertebrates and small fish as well as a place for fish eggs
What are the characteristics of stream flow?
Almost never uniform Slowed by friction and drag forces near the boundaries three dimensional
What is helical flow?
within three dimensional flow, sometimes helical flow is seen in deep streams/rivers as a secondary flow pattern A spiraling water mass that occurs in meander bends
Where do a lot of perceived stream problems occur?
in active erosion zone
What are the vertical velocity distributions?
What is laminar flow?
Regular smooth little mixing the idealized conception, but doesn't occur
What is turbulent flow?
irregular chaotic a lot of mixing of the layers
What is the laminar sublayer?
As you reach to the bottom of a substrate(right at the bottom), there will be an area where it is simply laminar, but very small
What is one of the major sources of turbulent flow?
When there is flow around objects which creates pattern varies at different discharges
What are turbulent headies?
voids where water is not flowing (dead zones)
What is the boundary layer?
extent in the water column to which friction and turbulence with the edge affects the flow of the water (not a fixed thickness) for most streams, the boundary layer is the entire water column
What does the froude number aid in?
helps to determine what kind of velocities do we want to repair the stream Fr < 1 subcritical flow (pools) Fr = 1 critical flow (riffles) Fr > 1 supercritical flow (rapids)
What are the benefits of streamflow?
food/nutrient in the current waste removal passive dispersal of organisms
What are the risks of streamflow?
Need to work (more energy) against flow disturbances seasonal variability
What is ecological integrity?
how we choose targets, how we set restoration goals, etc. all based on assumption
What are the consequences to an altered stream regime?
Changes in physical habitat (channel form) Altered life history patterns (spawning) Loss of lateral and longitudinal connectivity Spread of non-native species
Streams in forested watersheds are primarily what?
Heterotrophic, but still have populations of autotrophs
Streams in prairie regions and high mountain meadows are primarily what?
autotrophic, but often become heterotrophic once they drop below treeline
What are autotrophs?
organisms that acquire materials from the environment and energy from sunlight in the process of producing organic matter Autotrophic ecosystems make most of it's own food
What organisms makes up the autotrophs in the lotic system?
green plants, diatoms, and filamentous algae
What are heterotrophs?
Gain nutrients and energy by processing dead organic matter Hetertrophic eco system needs an influx, gets energy from something else
What are examples of heterotrophs?
fungi and fish
Streams in prairie regions tend to be...
autotrophic because it's not shaded, there's no leaves that provide energy so must make it themselves
Where do benthic autotrophs grow?
virtually all surfaces receiving light in flowing waters referred to as periphyton community
What are the classification of benthic autotrophs (periphyton community)?
Epilithon (species that grow on rocks) Epipelon (species that grow on soft sediments) Epiphyton (species that grow on other plants
What is periphyton?
a complex matrix of algae and heterotrophic microes attached to submerged substrata in almost all aquatic ecosystems serves as an important food source for invertebrates and some fish and can slow down path of contaminants
What does the lotic phytoplankton include?
algae protozoans cyanobacteria all free-floating, transported by currents
What are attached and benthic populations?
blue-green algae green algae diatoms
What are the characteristics of diatoms?
very diverse hundreds of thousand of species largest % of most stream's periphyton dominate during the winter, spring, and early summer
What are the four primary growth forms for macrophytes?
·Emergents:banks and shoals
·Free-floating: slow (tropical) rivers
·Submerged: midstream (limited by light penetration, current speed, and substrate type)
What characteristics attribute to a success and maintenance of macrophyte populations?
trough, flexible stems and leaves attachment by adventitious roots rhizomes stolons vegetative reproduction
What is rock snot?
an invasive diatom that essentially takes over a stream