Midterm Flashcards
1
Q
What technology and/or inventions increased the stream habitat damage caused by forest harvesting? (2)
A
Gas engines
Steam engines
2
Q
List 3 negative consequences of industrialized logging on stream habitat
A
- Loss of LWD input to stream
- Erosion and sedimentation
- Changed to channel morphology (eg. loss of habitat heterogeneity)
3
Q
What is the loss rate of LWD to streams (% per decade), and how long will the LWD deficit last in old growth streams that were logged to the banks? (2)
A
10% per decade
75-150 years because the trees need to grow first and the fall into the channel
4
Q
List 2 effects of decreased LWD on stream ecology and habitat
A
Loss of habitat complexity such as in-stream cover and refugia from predators, temperature, and flow
Changes to macroinvertebrate diversity and abundance and general losses of nutrient input to the stream
5
Q
What 2 changes in urbanized watersheds allow contaminated rainwater to flow overland and into streams, rivers, and lakes, as point, or non-point source pollution?
A
Mass increase in impermeable area and reduction of riparian vegetation has caused polluted runoff water to enter streams directly through overland flow rather than percolating into the groundwater and being filtered by the soil
Building of culverts and pipes that direct waste water into streams
6
Q
What are infiltration galleries, created wetlands, detention ponds, swales etc. designed to do in urban watersheds?
A
They are designed to increased the amount of impermeable area which lets the soil filter contaminants, planted vegetation increases interception,l to decrease overland flow so that there is less run-off. Wetlands are also designed as a nutrient and contaminant containment because the constituents settle at the bottom
7
Q
What year did riparian logging to the stream bank end in coastal BC?
A
1988
8
Q
What year did riparian logging to the stream bank end in interior BC?
A
1995
9
Q
What was the Carnation Creek experiment about? (2)
A
The Carnation Creek experiment was one of the leading experiments that showed the effects of clear-cut logging on salmonid habitat
It showed 3 different levels of logging (eg. clear-cut, retention etc.) and how they increased erosion, sedimentation, and decreased large wood etc.
10
Q
Studies in the H.J. Andrews Experimentsl Forest on the West slope of the Cascades, Oregon, indicates that the removal of vegetation from a forested watershed caused what kind of change in minimum streamflow? Provide one reason for this observed change.
A
Removing riparian vegetation causes low flows in the late summer and flashy flows in the winter. These studies showed that the minimum streamflow increases in the rainy period because there is no vegetation to intercept the water
11
Q
Why is watershed restoration potentially controversial?
A
Watersheds can span many jurisdictions, municipalities, private lands etc. and everything is connected in terms of the watershed and restoration success, stakeholders, and land-ownership and decision-making
12
Q
Why do we need to think of restoration within the context of “the watershed” and what timescales are we likely applying? (3)
A
Landscape-level views of restoration are important because whatever is happening upstream (whether it be pollution or erosion etc.), will affect the success of your restoration efforts
In restoration, we are likely applying a short-term fix such as the addition of LWD as cover, but we also need to take into account the restoration of processes such as planting riparian vegetation for future LWD inputs. We are attempting to accelerate natural recovery of ecosystems that could take anywhere from decades (LWD) to centuries to fix themselves
13
Q
What are the 3 main requirements for restoration to be successful?
A
Projects need to be:
- Science-based
- Have a holistic view
- Be professionally delivered
14
Q
What is needed for long-term and successful restoration? (2)
A
Focusing not only on short-term fixes such as adding LWD, but focusing on:
- Protection (influencing policies etc.)
- Process-based restoration that focus on providing future desired conditions
15
Q
Why have LWD complexes become so important in channel restoration efforts? (2)
A
They mimic a tree that has fallen into a channel with the root wad and all, which is the natural way things would have happened in old growth stands when red cedar or Douglas fir would have fallen in
Root wads are extremely valuable in collecting sediment
16
Q
Within the context of what threatens ecological restoration, what are the “4 H’s”?
A
Habitat loss
Harvest
Hatcheries
Hydropower
17
Q
What are 3 additional factors that can be added to the “4 H’s”?
A
Invasive species
Pollution
Climate Change
18
Q
Define COSEWIC (2)
A
Committee on the Status of Endangered Wildlife in Canada
They are an advisory committee made up of wildlife experts from the private sector, NGOs, academia etc. that decide on what species in Canada are in danger and should be listed on the Species at Risk Act (final decision is in the Ministry’s hands)
19
Q
What species have been declared “endangered” by COSEWIC but not “at risk” in BC in the Thompson and Chilcotin River systems?
A
The Thompson and Chilcotin Steelhead Trout populations
20
Q
What was the percentage of steelhead decline in the Chilcotin and Thompson watersheds between ~2000 and 2018?
A
There was a 79% decline in 2017/18 which was the all-time lowest numbers since records began in 1978
21
Q
What rationale was provided by the government of Canada for not declaring the Chilcotin and Thompson Steelhead as “at risk”? (2)
A
The Government of Canada ignored recommendations from COSEWIC and stated that an emergency listing would produce “suboptimal ecological, social, and economic outcomes relative to a comprehensive, long-term collaborative action plan with British Columbia”
(this sounds like they are passing the responsibility, and also how can B.C. have a thorough plan if legally the species isn’t listed?)
Meanwhile, populations are still low (4th lowest in 2020)
22
Q
Over the past 50 years, what is the percentage of estimated wildlife populations decline?
A
60%
23
Q
What method of restoration is critical in long-term rehabilitation and success of ecosystems?
A
Watershed scale, holistic approach
24
Q
Explain the River Continuum Concept (3)
A
Based on Equilibrium Theory in that:
- Processes within a drainage basin are linked and dependent on one another from the headwaters to the estuary
- As energy changes from the top to the bottom of a river system, the physical, chemical, and biological processes change (eg. as energy changes, banks might be eroded or sediment and OM might build up, and this affects the biotic community)
- Community structure and function adjusts to changes in: streamflow, channel morphology, detritus loading, size of particulate organic material, characteristics of autotrophic production, and thermal responses
25
Define “timing”
Refers to the actual timing (i.e. month, week, day) that a certain activity is proposed
26
Who just be coordinated with to ensure timing can be met?
You must coordinate with contractors, funding agencies, restoration team members, and regulatory agencies to ensure timing is met
27
How long can a delay be if a work window is missed? (2)
Delays can be a year if you miss a work window
| Some other consequences are loss of funding or contractual penalties
28
Define “sequence”
Sequence is the order of work and specific steps that need to be taken for the project
29
What is central to your sequencing strategy and why? What is an example? (2)
Planning is central to your sequencing strategy because without planning, you are less likely to have a successful outcome
For example, if you add LWD to the stream without stabilizing upslope banks first, your project will not be successful and you could be wasting a lot of money and time (and it could even be dangerous)
30
What is the result of a good planning process? (5)
Allocating funds and resource to the proper task
Increasing the likelihood of achieving project goals
Develop a good reputation among colleagues, funding agencies etc.
Ensure life and property is not at risk
Success for project is more likely
31
When was the “Water Act” updated and what is the new name? What is the primary purpose of this Act? (3)
The Water Act was changed to the Water Sustainability Act and it was updated February 29th, 2016
It’s primary purpose is to regulate water bodies to ensure that a sustainable input of clean, fresh water is provided to all of BC today and in the future
32
How does the Water Sustainability Act define “stream”, “stream channel”, “changes in and about a stream”, “aquatic ecosystem”, and “fish habitat”? (5)
Stream - any natural watercourse (including lakes, ravines, wetlands, or glaciers) whether or not they contain water or ice BUT does not include an aquifer
Stream Channel - in relation to stream, but including the bed and banks, both above and below the natural boundary, whether or not the channel has been modified, and includes side channels of the stream
Changes in and about a stream - any modification to the land, vegetation, and natural environment of a stream or the flow of water in a stream, or any activity within a stream channel that may have an impact on the stream channel (incl. banks, bed etc.)
Aquatic Ecosystem - the stream channel, the vegetation of the stream, and the water in the stream. Also includes any fish, wildlife, or other living organisms insofar as their life processes are carried out in the stream, depend on the natural environment of the stream
Fish Habitat - streams, ditches, ponds, and wetlands that provide food, water, and nutrients into fish-bearing streams, even if they do not contain fish or if they only have temporary or seasonal flows
33
How many days prior to commencement of the work must notification information be submitted for a notification and an approval? (2)
For a notification - 45 days prior to work. It a Habitat Officer does not respond, work can commence (although if they do, you must comply with specific terms and conditions for the change)
For an approval - 6 months prior to work. Engineer from the Resource Stewardship Branch should get back to you in 140 days
34
Where are notification applications submitted and who reviews them?
Submitted to Front Counter B.C. for review by a Habitat Officer from the Ministry
35
Where are approval applications submitted and who reviews them?
Submitted to Front Counter B.C. and reviewed by an engineer from the Resource Stewardship Division of the ministry
36
What is an in-stream work window?
Timing during which in-stream works have the least risk on whichever species the work window is for. Generally salmonids are during the summer
37
What specific level of COSEWIC listed species must be determined? (2)
All species listed with COSEWIC
| Red and blue listed species on SARA
38
What are the criteria of the lowest risk period for fish? (3)
No fish spawning is taking place
No eggs or alevins in the stream gravels
No overwintering juveniles present
39
What is a sensitive stream, and what is the importance of a sensitive stream designation?
A sensitive stream is a watercourse that warrants particular attention to protect the watershed’s fishery resource (this includes all of its tributaries)
40
How many sensitive streams are there in B.C.?
15
41
Who is ultimately responsible for the protection of streams and their habitats through the Water Sustainability Act?
The Ministry of Forests, Lands, and Natural Resource Operations, and Rural Development (MFLNRD)
42
What does RAPR stand for and what level of government is it? (2)
The Riparian Areas Protection Regulation
It is a provincial level of government but its purpose is to get municipalities to enact their own bylaws that protect riparian areas
43
Who is in charge of setting the Stream Protection Enhancement Area (SPEA)?
The municipal government sets general buffers for Stream Protection Enhancement Areas (SPEAs) under the Riparian Area Protections Regulation (RAPR)
44
Who is in charge of requesting the appropriate Stream Protection Enhancement Area (SPEA)?
If necessary, a Qualified Environmental Professional can request a different Stream Protection Enhancement Area (SPEA) from the municipal government
45
Under what circumstances would you submit a notification and an approval? (2)
You might submit a notification for: channel maintenance, restoration, stream bank stabilization etc. (smaller works)
You might submit an approval for: culvert installation, sediment pump installation, or dredging (more complex works)
46
Under what conditions are an Approval or Notification NOT required? (3)
1. Construction or replacement of erosion or flood protection works
2. Clearing of an obstruction from a bridge or culvert if it had the potential to cause a significant risk to public safety
3. In an emergency, in which case the Emergency Program Act (EPA) comes into play
(e. g. things like: project is required for national security, a response to a national emergency or emergency that poses an immediate risk to the public, environment, or property)
47
What are the 4 pillars of emergency management?
Mitigation
Preparation
Response
Recovery
48
Is the Water Sustainability Act the only set of rules and guidelines that must be followed when conducting work that affects fish habitat? If no, explain what other regulatory approvals must be gained (4)
No, there are many including (but not limited to) the Fisheries Act, the Species at Risk Act, the Riparian Areas Regulation, the Wildlife Act etc.
49
What is the difference between RAR and RAPR? (2)
RAR stands for Riparian Areas Regulation and it’s was changed to RAPR, the Riparian Areas Protection Regulation in 2019
A couple of things were amended, including a change in some of the language and the QEP must now take a Riparian Areas Regulation Course every 5 years
50
What is RAPR?
The Riparian Areas Protection Regulation is a provincial regulation that is meant to protect the features, functions, and conditions that are vital for maintaining steam health and productivity including the Stream Protection Enhancement Area (SPEA) designates by the municipality and Qualified Environmental Professional
51
When did the new Fisheries Act come into force?
August 28th, 2019
52
What was the purpose of the changes to the new Fisheries Act? (5)
1. Restore protections for fish and fish habitat
2. Enhance marine protection and habitat restoration
3. Improve project management
4. Preserve independent inshore fisheries
5. Strengthen indigenous role in project reviews, monitoring, and policy development
53
What is DFO? (2)
Department of Fisheries and Oceans
They are a federal body that governs the Fisheries Act for fish and fish habitat
54
What was the major change from before to after Bill C68?
Fisheries Act went from only protecting fish and fish habitat important to commercial, recreational, or aboriginal fisheries (under the Harper administration), to protecting all fish and fish habitat
55
What is considered “serious harm” to fish?
Death of fish (outside of fishing), or the permanent alteration to, disruption, or destruction of fish habitat
56
What waterbodies do not require a project review from DFO (4)
1. Artificial waterbodies like backyard ponds, drainage ditches, irrigation channels
2. Fish-less streams
3. Marine dumping sites that have been used in the past 10 years
4. Tailings impoundment sites
57
Describe some of the restoration activities that do not require DFO review
Maintenance of bridges, causeways, culverts
Drainage, flood control, and storm water and wastewater management
Flow management
Water diversion and dewatering
Habitat restoration, log removal or salvage, riparian vegetation removal
58
What Id the form of approval that DFO provides?
If you think that your project might cause harm to fish or fish habitat you have to submit a request to DFO. If they determine that your project could, in fact, cause such harm, you must fill out an Application for Authorization, and the project needs to be approved (generally with many conditions)
59
What is meant by Dynamic Equilibrium? (2)
A channel is always trying to balance its sediment supply with its sediment transport
Therefore, if a disturbance upsets this balance, a channel will adjust either its: width, depth, slope, or grain-size to re-establish equilibrium between sediment supply and sediment transport
60
What is the Flood Pulse Concept? (4)
Describes the movement, distribution, and quality of water, AND dynamic interaction between a river and it’s floodplain
Used to explain the energy and nutrient dynamic laterally from a river, rather than down a river like the River Continuum Concept
During floods, fish are able to access nutrients from the banks that they would normally not have access to, and floods pull or deposit organic matter from and to their riparian zones
Because large rivers (eg. Fraser River) get less nutrients from autochthonous and allochthonous means, they can have huge floodplains that allow for this exchange
61
What is the most important nutrient related to the Flood Pulse Concept and how is it recruited to the river? (3)
Carbon, and it can be recruited either:
Allochthonously - from leaf litter in the riparian zone, highest in headwaters
Autochthonously - from algae within the river, highest in middle reaches
Through floods that recruit leaf litter and deposit nutrients in very large rivers at the highest order reaches
62
What is the name of the stream ordering system that is commonly used?
Strahler Stream Ordering System
63
What stream type provides the best habitat for salmonids and why? (5)
Riffle-pool streams because there is an abundance of pools for refugia and rearing, and riffles for spawning
These streams have the 4 key ingredients for good salmonid habitat: food, water, cover, and passageway
64
Before restoring a stream channel, what are the main things you need to consider? (2)
You must determine the level of disturbance and the pre-disturbance state so that you can set targets and goals for restoration
In the absence of historical information, oftentimes it must be assumed that the pre-disturbance state would have been a typical morphology for the size/shape/location of the stream
65
Where are the most productive spawning habitat located? (2)
Mid-watershed because this is where the most frequent disturbance occurs (e.g. collection of debris, dam breaks, cycle of aggregation and degradation)
Spawning habitat is recruited from upslope and the banks, which are generally cobble sized, rather than downstream where it may be too fine to use for spawning
66
What are the main causes of spawning habitat degradation? (3)
Sedimentation of spawning gravels from upslope and bank erosion
Blowout of cobbles and gravels from high flows
Both which are increased by humans
67
What are the negative effects of fine sediment accumulation? (3)
Loss of space between spawning gravels to shelter eggs, alevin, juvenile fish, and other organisms
Prevents the entrance of oxygen into the spaces between the gravels
Reduced pushing out of CO2 and waste products
68
What are the methods for addressing sites that have been degraded by the accumulation of fine sediment over spawning gravel? (3)
Gravel cleaning
Gravel replacement
Gravel catchment structures
69
What must first be addressed before choosing a method to address sediment accumulation?
It is critical to first ensure that the recruitment of the sediment from upslope or stream bank id taken care of by either hill slope or stream bank stabilization
70
What types of stream conditions should gravel cleaning/placement be limited to? (3)
Streams with a lack of natural gravel
Display gravel retention characteristics
Have little or no sediment input from eroding hillsides or stream banks
71
Define gravel cleaning and how it is done (3)
Invasive procedure that uses heavy equipment to physically disturb the stream bed environment
Machinery is used to destabilize the stream bed and spawning gravels are cleaned through large-scale cleaning using bulldozers, excavators, or custom water jets
Small-scale cleaning can also be done using hand tools or high pressured jets
It is a difficult, invasive, and expensive process
72
Define gravel placement and what the technique is intended to do (3)
Gravel placement is meant to compensate for an identified loss of natural gravel supply to create habitat
There are two methods:
Direct habitat creation - through adding gravel mechanically or building of structures that can trap mobile gravels during high flows (these techniques often require maintenance and repeat application)
Passive habitat creation - by adding gravels to steam and letting natural hydraulic processes redistribute the material over time
73
Why are the largest errors in gravel placement? (4)
Not first addressing the source of sedimentation
Placing gravels in reaches that are too steep
Wrong time of year (restoration planning)
Not having a holistic view (dam letting water out)
74
What methods could you use to determine if a stream had the appropriate spawning substrate size? (4)
Wentworth Scale - use a corer or a shovel and then sift and quantify the percentage of fines, gravel etc.
Freeze corers with carbon dioxide or liquid nitrogen
Bulk Sediment Sampling Analysis
Wolman Sampling - type of pebble count sampling, measuring the rolling side of pebbles
75
Describe 2 types of bank erosion. Describe the type of steam and bank material of each (8)
Low magnitude, high frequency
High order streams with fine-grained beds such as meandering channels erode slowly over time (shift)
Cohesive forces hold grains together (clays
and silts) but non-cohesive materials can still be present
Slumping and geotechnical (gravity) bank failure most common
High magnitude, low frequency
Low-order streams such as in the headwaters erode in mass wasting events
Made of non-cohesive materials that erode and result in undercut banks at toe
If roots are not deep enough, can result in bank breaking off (catastrophic during flood event)
76
Where in the cross section of a river does the bank destabilize if eroded? (3)
In all sections - the type of destabilization only differs with the type of characteristics of the bank material (I.e. coarse sediments, fine sediments, organic matter etc.)
In fine-grained rivers, bank can destabilize when the toe of the lower non-cohesive later is eroded leading to slumping and geotechnical bank failure (predictable process)
In coarse-grained rivers, bank can destabilize when toe of non-cohesive layer is eroded as well, however, stabilization depends more on rooting depth of vegetation rather than the presence of cohesive materials. If there is a lack of vegetation, hydraulic forces will result in the removal of coarse materials during flooding events, leading to bank failure
77
What is one natural mitigation to bank erosion?
Leave buffer zones with natural deep-rooting vegetation
78
What secondary habitat degradation occurs along with bank erosion? (5)
```
Loss of protective cover
Reduced channel depths
Increased stream temperatures
Infilled pools
Excessive sediment in spawning gravels
```
79
What is the hyporheic zone? Why is it important? (5)
Is the interface between the surface water and ground water that is immediately under the steam bed (“porous stream bed”)
It is important because:
Exchange and cycling of stream waters
Maintenance of stream temperature regimes
Moderation of flow or temperature changes
Provision of important habitat for stream invertebrates, juvenile fish, and other aquatic life especially during incubation and periods of low summer or high winter flows
80
What are the zones of a bank and which is eroded? (3)
Overbank
Bank
Toe - erosion point
81
What are the 3 groups of bank stabilization techniques?
Rock methods
Vegetative methods
Integrated methods
82
What are rock methods? (4)
Well-established method in bank stabilization using large angular boulders or rip rap to armour banks and redirect flow
Can be used to create fish habitat structures in the stream, rock benches to induce eddies, or shear zones to create fish rearing and resting areas
Requires precise planning, construction, inspections, and maintenance
Can be very expensive
83
What are vegetative methods? (7)
Bank stabilization method using vegetation and roots
Is a less “hard” method than rock techniques, and is used is more low gradient streams where riparian vegetation has been removed
Can be very cost effective
Self-maintaining
Requires the restorationist to gather a lot of information about the surrounding ecosystem (eg. species will depend on things like competition, soil, and shade characteristics)
Requires specific timing for when it should be conducted and is generally done in times when the plants are dormant (spring or fall)
Vegetative methods alone do not provide fish habitat
84
What are integrative methods? (4)
Bank stabilization techniques that use a variety of organic and inorganic materials such as rocks, soil, timber, plants, and fabrics
Generally used to secure banks in areas where either rock or vegetation alone will not suffice
Have become popular in areas where bank restoration is limited due to close proximity to roads or sensitive habitat
Use has increased in recent years to balance habitat issues with budgetary constraints and site conditions
85
What are the examples of rock methods? (5)
```
Groynes
Riprap
rock toe keys
Tie-backs
Rock gabions/baskets
```
86
What are the examples of vegetative methods? (5)
```
Herbaceous ground cover
Rooted stock
Live cuttings
Brush mattresses
Brush layers
```
87
What are the examples of integrated methods? (5)
```
Joint planting
Vegetative geogrids
Live cribwalls
Tree revetments
Large wood debris
```
88
All stabilization design methods must include: (9)
```
Design flow at a 100-year event minimum
Max slope angle/current velocity
Use of filter material to prevent loss of fines
Toe protection
Overtopping/outflanking protection
Incorporation of fish habitat features
Access and right of way areas
Source for rock or vegetation
Proposed areas of cut and fill
```
89
What are Rock Toe Keys? (3)
Involved the excavation of the channel bed in the toe zone and the placement of large, hard, angular rock below the expected level of scour to protect it from undercutting (usually 1m below the lowest thalwag)
Method should be employed at all sites where toe erosion has been identified as a primary mode of bank failure
Can be paired with geotextiles and plantings
90
What are Rock Gabion Baskets? (4)
Gabions are rectangular baskets fabricated from a hexagonal mesh of heavily galvanized steel wire
Baskets are filled with rock and stacked on top of one another to form a type of wall
Depend on the interlocking of rocks inside the mesh for internal stability, and their mass or weight to resist hydraulic force
They are a porous type structure and can be vegetated, but otherwise are considered a “hard” structural solution that has minimal habitat and aesthetic value
91
Riprap/rock revetments
Layer of large, angular rock placed in the bank zone to limit erosion (chance of failure increases with slope)
92
Groynes
Structures that are attached to one bank and protect erodible areas by directing the flow to the middle of the channel (as a sort of deflector, generally coupled with bank protection on the other side)
93
Tie-backs
Use of rock as a retaining wall placed perpendicular to the bank to prevent a straight reach from lateral migration
94
What is Herbaceous Ground Cover? (3)
Includes the use of temporary erosion control grasses for ground cover on bare soils in the bank and overbank zone before shrub/tree plantings
Not effective on its own as a stream bank rehabilitation measure
Can outcompete native vegetation
95
What are Live Cuttings? (7)
Most common technique used in BC
Consists of woody plant material often taken from first- or second-year growth of species that will root from cuttings
Usually use native species such as Red-Osier Dogwood and Willow that root easily and provide a quick means of controlling soil erosion and shallow siding
They are pioneer species and will survive long enough for successional vegetation to establish
Inexpensive
Best to use on moist, well-drained banks with limited erosion (can plant in areas with more erosion by using wattle fencing)
Planting densities are based on desired frequency (eg. 1m spacing in a grid pattern)
96
Brush layers
Live cuttings or rooted stock placed in successive horizontal rows dug into the bank parallel to the stream
97
Brush mattresses
Layer of live branches laid flat in the bank zone and secured with stakes and wire or rope then covered with soil. Hope is there roots establish
98
Rooted stock
Can be used if rapid establishment of root support is required (generally more expensive but is best for restoration in buffer zones)
99
What are Joint Plantings? (3)
Life cuttings installed within a riprap matrix, either during or after riprap placement. Installation during riprap placement dramatically increases survival of plantings and decreased labour time
Improves bank protection by forming a root mat and increasing deposition of sediment and debris
Can have high mortality rates if stakes are not driving into the underlying soil layer well enough
100
What are Live Cribwalls? (7)
Frameworks of lots or untreated timber, rock, and live cuttings
Installed in steep slopes as steep as 1H:10V
Steeper areas require analysis for anchoring
Live cribwalls provide immediate erosion protection and supply overhanging vegetation and space for fish
Often include a rock toe key that should be built during low flow periods
Used in regions with direct fluvial attack but should not be used if risk of channel avulsion is high
May require considerable disturbance to riparian areas
101
Large wood debris
May be used as a component of integrated bank protection to improve habitat by providing cover, nutrients, and hydraulic diversity (species, size, and placement very important)
102
Tree revetments (3)
Act as a permeable structure to protect banks from fluvial scour and toe erosion
Whole conifers anchored to streambanks for low velocity sites with non-cohesive banks
Or
Tree-rock-live cutting structure for moderate energy sites with cohesive or non-cohesive material (cohesive might demand a trench be cut)
103
Vegetative geogrids
Similar to brush layers but soil fill is wrapped in geotextile material made of whatever is appropriate for that area (eg. Flax)
Is good for high slopes where it can’t be stepped back
