Final Test Compilation Flashcards
What use do holding ponds serve in a watershed?
Stabilize water flow. Act as a storage system until water is fed back into the main stream.
Movement of water actually has allot to do with soil. Explain why this is and indicate which texture of soil holds more water. mkay?
Since water that hits the earth is stored and moves through soil we have to know how it effects water. Most soils have around 40 - 50% pore space so there is allot of space for water to occupy.
Fine textured soils like silts and clays tend to hold more water and are more susceptible to mass wasting and slope instability issues when exposed to high volumes of water.
Explain in detail the effects of rain on snow.
eg. how does it effect drainage?
- infiltration?
- mass erosion, debris channels and culvert blowouts
Rain on snow can be problematic because it adds large volumes of water that in some cases exceed the capacity of culverts and even natural stream formations, resulting in high turbidity and habitat degradation. Rain on snow also causes increased erosion of soil substrate which does not infiltrate the frozen soils and carries the sediment and debris into streams.
How can rain on snow events be avoided?
Sustainable methods include harvesting areas that are susceptible to rain on snow events over long periods of time so that the canopy creates a buffer zone and the natural processes that allowed the forest to grow in the first place can be maintained.
Another method would be to simply reduce or decide not to harvest rain on snow sensitive areas
What is the basis of the BC stream classification system?
-2 main conditions
Channel width
Use by fish at any time throughout the year
What is the biggest factor in road degradation?
Precipitation
especially usage during precipitation events!!!
This might be an old question but these are fair game on the test
What is the adiabatic lapse rate?
Adiabiatic lapse rate refers to the rate at which air cools as it rises
it is roughly -6.5 degrees per 1000m
How does a sedimentary bedrock composition effect water movement?
Sedimentary rocks are porous and create channels for water to permeate. They get tilted due to plate tectonics which results in the movement of subterranean water in and out of watersheds.
What are 2 things that influence Basin Geology?
Bedrock composition
Water location and flow
List some drainage patterns
There were 5 listed in the lectures… mkay?
- Dendritic
- Parallel
- Trellis
- Angular
- contorted
Give 3 examples of stream types and briefly differentiate.
Perennials
-flow throughout the year due to ample groundwater and precipitation inflow. Usually found near the bottom of slopes and are fed by multiple smaller tributaries.
Intermittent
-Flow for at least one month per year in response to seasonal runoff. Usually mid slope
Ephemeral
-Do not flow year round due to inadequate precipitation and groundwater availability. Usually upper slope, small streams
What is alluvium?
material that has been transported by running water. Very coarse, rounded material due to loss of loss of most clay/silt fraction downstream.
What two soil qualities heavily influence infiltration, percolation and storage of water that hits the earth.
Depth of soil
Soil texture (Bulk density/Porosity)
what two terms are used to describe the depths of soil?
Hint: based on thickness…
if you don’t think this relates to hydrology feel free to skip this
Blankets - Deeper than one meter
Veneers - Less than one meter (rocky outcrops)
What is an indirated soil horizon and how does it effect water movement?
Also what color is it?
what conditions make it possible?
Indirated soil horizons are red and are the result of water evaporation which causes oxides and other minerals to be deposited as the water moves upward. Creates a restrictive layer that stops water from permeating it.
It is a result of seasonal changes in the water table
In what case will water not infiltrate soil? What is the result?
If the soil is frozen or fully saturated, water will not infiltrate it and will instead cause “overland flow” which leads to mass erosion, stream flashiness and sedimentation.
What is viscosity? What important process does it effect?
Viscosity is a measure of a fluids resistance to deformation and changes in response to temperature.
It has an effect on infiltration of soil by water. The warmer the water the better it will infiltrate a soil.
Explain field capacity
When soil has been saturated and left for 2 days, how much water is left in its pore space.
Basically equates to the water available to plant life.
Whats the PWP?
Permanent Wilting Point
Point at which no water is left for plant life
what two properties of water contribute to Field Capacity?
Adhesion and Cohesion
What does stream gradient refer to?
The slope of stream. During a transect the gradient would be recorded at every station.
What are some shapes that stream gradients can take?
Hint: there were 6 listed in the lecture but the last 3 are just combinations of the first 3… mmmkay?
Concave (thicker soils) Convex (thinner soils) Straight Concave convex Convex concave Concave straight
How is the shape of a stream determined?
What does it effect naturally? industrially?
Largely a function of bedrock geology, glaciation and erosion
effects bank stability, groundwater flow, road location and harvesting methods.
How can you define alluvium in a stream bed?
Coarse rounded material
Different vegetation complex than land above
What is the basic definition of a stream?
A natural water course having an alluvial channel and consistent banks.
What is a stream reach?
A section of stream with repeating characteristics
ex. pool, riffle etc.
As long as the pattern is constant the reach can be as long or as short as those conditions last… mkay?
List a few stream characteristics
- pools
- riffles
- cascades
- bank undercuts
- cascades
- falls
- calm stretches
- large woody debris
- channel substrate size
What would be the ideal complex of characteristics for a stream?
In a perfect world 1 pool per 7 stream widths would be a prime stream.
10m width should equate to 1 pool every 70m
What would be a healthy stream shape?
What stream shape has a negative impact on the environment?
Healthy streams are usually on a very mild gradient and meander in a curving zig zag pattern.
A stream that would have a negative impact on water quality and turbidity would be a straight stream. Straight streams are fast moving and cause rapid soil erosion, resulting in soil instability. These usually don’t occur naturally and are a result of the removal of the soil stabilizing riparian zone in the days when aggressive harvesting was the norm.
What does beadload refer to?
What does it compose?
The material between the banks of a stream such as: Gravel Boulders Sand Silt
Composes: gravel bars deltas fans terraces
Give some points that indicate a stable stream
Stable
- Channelized
- Stable conifers on bank
- Large stable organic debris
- Shallow undercuts
- Meanders
- Clean gravel
- 7:1 riffle to pool ratio
Give some points that indicate a disturbed stream
- Braided channels
- Lack of channelization
- deciduous trees along banks
- large meandering gravel bank
- dirty gravel
- lack of structure
- piles of small woody debris
- parallel woody debris
What is a littoral zone?
Define it and then give examples
In forestry; a littoral zone, a.k.a. marine sensitive zone is any area used by fish for feeding, resting, seeking refuge or spawning.
they include:
- shoreline shallows
- sloughs and seasonal flooded depressions
- backwater channels and estuaries
Why are backwater channels so important to coho in particular?
During a vulnerable part of a coho’s lifecycle, the fry swim through small underground spaces that have been saturated by groundwater in order to reach backwater channels. Since the channels have a constant inflow of ground water they do not freeze and offer protection, food and habitat to the coho fry.
Briefly describe what a subduction zone is and why its important
The subduction zone is where tectonic plates clash and one is forced below the other. This causes land to rise from the sea and can cause bedrock to be tilted on angles that effect water movement.
What is the full manning formula?
Just kidding what is the simplified formula? indicate what the symbols mean
Q=AV
where Q = discharge in cubic meters per second
A = Cross sectional area in square meters
V = Velocity in meters per second
What is Wp?
How do you identify it?
Wp = Bank full width
Defined by:
-Change in vegetation
-Slope or topographic breaks along bank
-Undercuts in bank
-lower extent of lines on boulders (moss ends)
-change in particle size (coarse cobble - fine grain)
What is a hydro graph?
What are some factors that influence it?
- A visual depiction of a streams response to a precipitation event
- Influenced by basin shape and slope
How would a round basin affect a hydrograph in comparison to a narrow basin?
A round basin will have a lower flow than a narrow basin
What is a Weir?
common weir design?
how does it work?
A gauging station that measures stream flow and response
Common design is V notch model
Head flow is taken at a distance and width is predetermined by weir so that flow can be measured
Define Riparian area
The interface between land and waterbodies including streams, wetlands and lakes. Surround water bodies and are composed of moist to saturated soils. Have significant ecological importance and are necessary for the propagation of our forests.
Define turbidity.
What does it indicate?
Siltation and cloudiness of water.
Indicates instability in stream
What do steep and shallow slopes indicate?
Steep - wide area of effect
Shallow - narrower area of effect
How does large woody debris contribute to stream structure and overall wellness?
How long does it stay in a stream?
Large woody debris gets lodged in such a way that the water flowing over it creates pools and increases aeration of water.
It decays very slowly (basically as long as it took to grow) to feed fungi and algae at lower end of food chain
Provide shelter for fish
List some points that make riparian areas so important to the ecosystem
- Source of large woody debris
- Source of leaf and insect litter (food for fish and organisms)
- Provide shade to keep water cool for fish
- Provide essential flight corridors used by key species
- Breeding ground for insects that provide food for many species and serve a key role in the food chain.
- Stabilize stream banks with roots of conifers
- Prime habitat and feeding grounds for many organisms resulting in a huge increase in biodiversity.
How do riparian areas effect water quality?
Act as a filter for sediment in the groundwater before it gets into the stream.
Differentiate between the RMA, the RZ and the MZ on crown land.
Hint: these are abbreviations for the different parts of a riparian area
RMA is Riparian management area and is composed of 2 parts
The RZ (Reserve Zone) Like the name implies, we are forbidden from harvesting or affecting the reserve zone unless we have chosen to make a crossing in which case strict precautions are taken to preserve the natural processes in place.
The MZ (Management Zone) In this zone we have the choice to selectively harvest mature (>12cm), commercially viable timber as long as it is done in such a way that does not negatively effect the reserve zone or other trees in the management zone. For instance tree's are fallen away from the stream and any small woody debris that is added to the stream because of logging activity must be removed.
What requirements does timber have to meet to be considered merchantable?
Commercially viable species
greater than 12cm bole
How do the rules for Riparian Areas differ between private and crown land?
On private land, the only areas that are required to be protected are fish bearing waterbodies and water license streams.
What widths correspond to each stream class in the BC stream classification system. Don’t forget about the fish.
Start at S1
Fish bearing S1- >20m S2- >5-20m S3- 1.5-5m S4-3m S6- <3m
At what stream gradient would you assume fish could not gain access?
None, you should never assume.
But… if the gradient is greater than 30% it is unlikely you will find any fish.
Explain what is meant by the term ecological anchor
Give an example
Ecological anchor refers to a certain type of habitat that has disproportional importance to the ecological community.
For example wetlands in the prince george area are important but not hugely significant since there are allot of wetlands in that BEC zone.
But a wetland in the ponderosa pine BEC zone would be considered an ecological anchor because wetlands are much less common in that climate. Species in these climates would show increased dependance and travel great distances to use the wetlands.
Define a wetland
differentiate between simple and complex
-Areas of shallow, open/semi open waters that are permanently or intermittently flooded.
A wetland is considered complex if its riparian area overlaps with the riparian area of another wetland and simple if it does not.
What is the basis of differentiation for wetlands?
Size
BEC zone
Proximity to other wetlands
List some features of wetlands that make them so important to the ecosystem
- Filter pollutants / Sediments before they enter waterbodies
- Act as sponges to reduce flooding and ease droughts
- Reduce soil erosion by slowing runoff
- Provide shade and ground water to reduce water temperature for fish
- Provide water, food, shelter and breeding ground to many species.
List some sustainable management practices when it comes to riparian management zone.
- Retain all wind-firm trees with roots embedded in bank.
- Remove dominant conifers and retain 50% of remaining stems within 10m of channel.
- Fall/Yard away from zone
- Do not damage remaining veg
- Retain non merchantable veg within 5m of stream
- Maintain pre harvest conifer to deciduous proportions
What is the rule of thumb when it comes to culvert construction?
If Area of Stream = 3 square meters what size of cylindrical culvert must you install to meet the capacity requirement?
what about a half pipe?
Culvert must accommodate 3x the cross sectional area of the stream
A = pai(r)2
If 3m = pai(r)2 just solve for r
r=1.7m
So diameter of culvert must be 3.4m
To calculate the diameter needed for the halfpipe you would just double the input area in the equation so instead my 3 square meters you would solve for 6 square meters.
Hopefully that makes sense to everyone…
What is the deciding factor on whether to use a box culvert or a bridge?
Size of stream
Why do we have to make culverts to withstand 3 times the volume of water as normal?
To accommodate a 20 year flood
In what way does forest cover effect watersheds?
Forest cover reduces the amount of water that reaches the ground
The trees themselves remove massive volumes of water as a function of transpiration. The loss of forest cover, especially on slopes can lead to mass wasting events and are sure to increase the speed at which water enters the streams therefor increasing the turbidity and debris torrents. This effect is dramatically magnified in rain on snow events.
How does the introduction of fertilizer effect water?
What about pesticides?
how does this stuff get into our streams?
When fertilizer gets into a stream the water is considered contaminated. The result is the reduction of oxygen in the water due to decomposing organic matter and the associated algal blooms and rapid increase in aquatic plant growth that fertilizer invokes.
The effect of pesticides is quite obvious. They were designed to kill organisms mkay?
These two substances can enter streams if appropriate precautions are not taken during forestry operations. Blowouts and mass wasting events resulting from poor road and culvert construction can also lead to the introduction of these harmful substances into streams.
Do riparian areas include green ocean shores?
Well yes they most certainly do!
What is the key feature of riparian areas when it comes to diversity?
more ecological diversity than surroundings
Briefly define biodiversity and ecosystem
Biodiversity - Refers to the number of different species associated with an area
Ecosystem - Community of living organisms and non living features that form an interdependant system
Why are wind-throw trees considered a positive thing in our forests?
They open up the canopy for light to get to forest floor and facilitate regeneration of understory.
How does an intact riparian zone help the forest after logging?
- Leaves the most valuable animal habitat intact.
- Provides travel corridors for continuation of migration and animals that travel
- Water that goes through riparian zone deposits sediment and nutrients that are recirculated into the surrounding forest by stabilizing riparian root networks and mycorrhizal relationships.
What are some species that are completely dependant on the riparian and at risk?
- bats
- pacific giant salamander
- tailed frog
