Natural Processes and Erosion: CCLT 2011, Part 2

Natural Processes Part 2
Coal River Springs, Southern Yukon

Let’s look at how natural systems address the limitations or filters preventing natural recovery of disturbed sites.
Burrowing Owl
Erosion is one of our most significant problems

Universal Soil Loss Equation
X = RKSLCP
Where:
X = the computed soil loss in tons (dry weight) per acre from a given storm period
R = the rainfall erosion index
K = the soil erodibility index
S = the slope gradient factor
L = the slope length factor
C = the cropping (vegetation) factor
P = erosion control practice factor

Rainfall Factor (R)
The rainfall factor for Vancouver Island is about 200 while in Calgary it is about 50. Vancouver Island winter storms (Nov. - Feb.) give heavy rainfall over long periods.

Soil Erodibility Factor (K)
The soil erodibility factor ranges from 0.02 - 0.69 depending on the texture, structure and permeability of the soils. Fine textured cohesionless soils will have a soil erodibility factor which approaches unity.

Slope Length and Steepness Factor (LS)
Soil loss increases dramatically on steep, long slopes:
100 ft. long slope @ 10%, LS = 1.4
100 ft. long slope @ 20%, LS = 4.2

Cropping (Vegetation) Factor (C)
The vegetation factor ranges from 0.45 for no vegetation cover to 0.003 for a 95% cover of grasses and legumes. Vegetation is one of the easiest factors to manipulate and provides one of the biggest benefits.

Erosion Control Practice Factor (P)
The erosion control practice factor represents the reduction in soil loss resulting from soil conservation measures (contour ploughing, terracing, fibre matting, etc..). Effective erosion control practices can significantly reduce erosion (soil loss)

How Can We Change Soil Loss? (X)
We can’t change:
R, rainfall erosion index
K, soil erodibility factor
We can change:
LS, slope lengths and steepness
C, cropping factor
P, erosion control practices factor

Changing C, Cropping Factor:

C = 1.0 for bare ground
Treatment C value
Fall rye 0.1
Sod 0.01
Permanent seeding (90%) 0.01
Wood fibre mulch 0.1
Fibre matting 0.02

Surface Conditions Factor (Cs)

Loose as a disked plough layer, Cs = 1.0

Treatment Cs Value
Compact and smooth, 1.3
(scraped with a bulldozer)
Loose with rough surface 0.8
Loose with smooth surface 0.9

Changing Erosion Control Practices Factor (P)

Normal erosion control practices at construction sites (check dams, interceptor berms, chutes & flumes, etc.) yield a P value of 0.50.
Treatments such as contour wattling can reduce P to 0.05.

Typical Erosion Rates
(tons/mile2 /year)
Undisturbed Forest Land 13 - 83
Agriculture 1,000 - 70,000
Urban Construction 1,000 - 100,000
Mine Construction 50,000 - 150,000

Solution erosion, CaCO3
Types of Erosion

Raindrop erosion
Action: Protect the soil surface
How:
- by establishing vegetation
with netting or mats
with mulches
with hydroseeding mulch
- with gravel or rock

Once the soil is in the air, it can easily be moved down the slope.
Raindrop erosion
During a heavy rain, as much as 224 t/ha of soil can be lifted in the air ready for erosion…

One of nature’s solution to heavy fall rains on the Coast

Another solution to heavy rain...

Swordferns
Note funnel-like shape that channels rainfall directly into the ground.

Evergreen plants provide erosion protection by putting up umbrellas
Salal

Oregon grape

Plant shape helps capture moisture
Prevents rainfall from running off
Festuca altaica

Festuca roemeri
Native Garry oak ecosystem grasses show the same patterns

Look at the shape of the leaves and stems of this willow

Sheet erosion
Rill erosion
Gully erosion

Sheet Erosion
Action: Prevent overland flow:
How:
- Create rough loose surface
- Top-dress with woody debris
- Straw baffles (expensive)
- Sod strips (expensive)
- Armour surface (expensive)

When nature clears the forest, she prevents erosion by laying down a bunch of large woody debris

Rill erosion
Action: Prevent / control flows
How:
- Make the surface rough and loose
- Armour gully channels
- Slow velocities (non-living)
- Bioengineering

NOTE: Matting not effective for sheet, rill or gully erosion as the erosion may occur under the matting.

Streambank Erosion
Action: Protect channel banks, slow flows
How:
- Armour channel (riprap)
- Drop structures (slows flow)
- Bioengineering (various)
- Slow stream velocities

Nature bends channels to increase length and slow flows.

Large woody debris with root wads attached help to hold banks together and provide natural armouring.

Mass Movement Erosion
Action: Depends on source of movement
How:
- Need to develop specific solutions to specific problems

Erosion can move massive amounts of material in short times

Erosion can happen fast
“Son of a ditch”!!!

This old drill site was left in a smooth and compacted state…

A heavy rain fall caused pooled water to spill over the side

With disastrous consequences…

Erosion control practices that made things worse…

…but they meant well.

How does nature deal with flowing water on steep slopes?

Mass movements
Building waste dumps that fail is unacceptable…

Soil slump

Mass movements
Soil slump

Small slumps under straw blanket

Soil slumps under spray on blanket

Natural mass movements

Natural mass movements associated with melting permafrost

Large ice lenses form the scarp on these slides

A history of permafrost melt slides…
…a history of natural solutions.

The start of something big ???

Exfoliating granite

Cryoturbation (stone stripes)

Solifluction

Groundwater piping

Aeolian deposits – Wind erosion

Wave erosion

What are the filters that are preventing the recovery of shorelines?
Erosion is one of the primary filters that limits the establishment of shoreline vegetation.

Shoreline pioneers can control erosion and start the processes of succession.

Here a band of willows protects the shore from erosion by damping wave action at a variety of water levels.

Yellow pond lilies can help to damp the waves, allow sediments to collect and start the processes of recovery.

Using emergent aquatic plants to protect shores
May
August

Rill meter
Pig

I guess this means…
…it’s lunchtime…

How can we solve erosion problems?

Over-steepened slopes erode…

A cautionary tale… Cook Creek,
January 8, 1997

Erosion of immature sod partially plugged grizzly, January 8, 1997.

March 25, 1997… a similar storm…

March 25, 1997… the grizzly …

March 25, 1997… the gully …

March 25, 1997… the salmon stream …

Another cautionary tale … Nile Creek

Nile Creek

The gully … …The clean-up

Changes to the physical conditions of the site to control erosion.

Erosion solution - Kemess Mine tailings dam

Spreading topsoil

Erosion starting on smooth surface before spreading is even completed.

Making it rough and loose

Roughened the whole surface

Roughened the whole surface

Added woody debris and planted trees and lupines
Fall 2008

August 5, 2009
No signs of erosion from spring break-up

August 5, 2009

June 8, 2010
Aspen
Lupine

Where spring melt overwhelmed infiltration capacity each hole acted as a settling pond

Making surfaces rough and loose controls erosion and enhances native species establishment.
Cost of rough and loose treatment at Kemess Mine was $715/ha while hydroseeding costs over $2,500/ha

Till borrow pits were covered with rough and loose micro-topography

Large waste dump slopes covered with rough and loose micro-topography

Gas plant site to be restored, March 11, 2010

Rough and loose, April 14, 2010

Rough and loose traps snow

Planting pioneering vegetation, April 14, 2010

Planting pioneering vegetation, April 14, 2010, note fence.

Watering in the cuttings, April 14, 2010

Cuttings growing, June 24, 2010

Cuttings growing, July 15, 2010

Cuttings growing, July 15, 2010

August 17, 2010

August 17, 2010

September 11, 2010

September 11, 2010

September 11, 2010
Red-osier Dogwood

October 2, 2010

October 2, 2010

October 2, 2010

Cutting the nose off this slope.

Leaving the slope rough and loose

Covered with coarse woody debris

Designing a Stream Daylighting Project to Control Erosion and Prevent Invasive Plants
Starting with a tangle of blackberries...

Designs developed...

... including restoration treatments

Clearing the site and laying out the new channel...

Started digging...

But the banks were cut smooth...

Nature doesn’t make smooth surfaces...

...so we taught the excavator operator how to make things rough and loose (natural erosion prevention)...

...by taking a scoop and then letting it fall back on the slope.

We made it all rough and loose, found a pipe and started the revegetation using pioneering species.

We made the waste area rough and loose then covered it with the woody material we had cleared from the site and covered the disturbed area with leaf mulch – another natural erosion control tool.

By the time we take the creek out of the pipe, the banks will be revegetated and there will be no “space” for invasive species.

May 31, 2009 – plants starting to show up

Joint planting used in culvert headwall

Joint planting used in culvert headwall
August 2, 2009

April 15, 2010

July 3, 2010

August 8, 2009
There will be a bit more planting to complete the job later in the fall

Dense spacing of live staking used to avoid invasives and move to a pioneering woody stage of succession
May 31, 2008

By using tall cuttings we are creating an instant shrub-land that will prevent blackberry growth
August 2, 2009

April 15, 2010

April 15, 2010

May 31, 2010

July 3, 2010

March 6, 2011

Dawson Creek site – erosion waiting to happen…

So we made it rough and loose...

...added woody debris...

...and planted a bunch of cuttings.

These treatments can be used to replace traditional grass and legume seeding at mine sites.

Including the addition of woody debris and…
Note different North and South exposures

…a fence to keep out the elk (biotic filter).

Let’s look at some tough sites and some solutions based on natural processes

When we look at natural patterns of vegetation establishment what do we see?

Vegetation establishes in pockets and patches...

We can make pockets of soil and then plant things in them.

People like to build houses at the top of sand cliffs and then they find the cliffs erode...

These are tough sites as the natural solution is to erode the slope until a stable angle is reached.

But if you have a university at the top of the slope, allowing the cliffs to erode is not an option.
UBC Slopes, Winter 1988/89

Soil bioengineering is the use of living plant materials to perform some engineering application

UBC Slopes, March 6, 1989

Doesn’t change slope
Changes conditions for vegetation growth
1989

Nature’s barbed wire…

UBC slopes initial test planted winter of 1987/88, May 7, 1988

UBC Slopes, May 28, 1990

UBC Slopes, January 18, 1990

UBC Slopes, 1996

UBC Slopes, March 25, 1999

UBC Slopes, March 25, 1999

UBC Slopes, March 25, 2510

2000/01 slope

From the bottom at the start…

Geogrid reinforced fill

Compacted

Wattle fences used for facing

Wattle fences used for facing

By June 6, 2001 the slope was green.

Posts and horizontal pieces sprout

UBC Slopes August 18, 2005

Moisture sensitive soils treated with “Soil Guard”

Moisture sensitive soils treated next with coco-fibre matting

… with a similar result…

As the winter progressed, the slope continued to unravel.

Repairs initiated…

Wattle fences hold the mud but let the water out.

The cuttings love the wet soil…

… and grow well.

May 21, 2008

May 21, 2008

March 23, 2010

March 23, 2010

53o till slope over 5 m rock cut
July 4, 1986
October 29, 1986

July 20, 1987

May 26, 1988

July 10, 2005

August 1, 2009

Road deactivation near creek
August 18, 1987

Sept. 22, 1987
Sept. 22, 1987
Lunchtime

July, 1988

July 9, 2005

August 1, 2009

Road fill failure

At construction, fall 1995
June 25, 1997

Catching rolling rocks

Two types of treatment
$320,000
$13,000

Substantially built…
…but does it contribute ecologically to the site?

Roger’s Cellular Silverdale slide

Roger’s Cellular Silverdale slide

Roger’s Cellular Silverdale slide

Partially completed

Nearly done…

Looking down from the top

The crew at completion…

May 18, 2006.

June 18, 2007.

June 18, 2007.

June 24, 2008.

June 24, 2008

Friends of Bowker Creek

CRD Bowker Creek project

Ready for rooted riparian plants

Happy Crew…

Bowker Creek in the spring of 2006

Bowker Creek in the fall of 2006

October 2, 2007

October 19, 2008

July 23, 2009

Steep landslide

Wattle fences
October 11, 2008

Very steep slopes can be treated using pioneering species
October 11, 2008

July 8, 2009

June 18, 2010

Wattle fences installed May 8, 1987

Wattle fences not growing much… August 26, 1987

Wattle fences about the same …
July 16, 1999

About the same…
July 9, 2005

About the same…
August 1, 2009

So what can we do with dry sites where rolling stones are preventing vegetation growth?

Pulled back road fills.

Modified brush layers

Modified brush layer

Looking down the slope – no path for rolling stones

Cuttings remain exposed even when bench is full

Starts successional processes…

Assists the recovery of damaged ecosystem

Allows vegetation establishment under harsh conditions

Three different species in this MBL.

Can treat large areas

Provides pockets to capture fines

Open slope failure down to basal till, July 31, 1996

Vegetation becoming established, August 23, 1997

A cautionary tale…
June 20, 1997

Covered with MBLs – October 25, 1997

Solved ??? the Mowhokam Creek Slide…

March 21, 1998 mud flows

March 21, 1998 – surface soup

Surface mud flows topple horizontal structures

Wattle fences & MBLs have limited resistance to toppling - 1998

However, even a little stability helps - 2006

Still more work to do - 2006

Typical toppling failure

Live Smiles
Uses catenary curve to “suspend” mud

Suspension bridge, Juan de Fuca Trail

Like a wattle fence built in a curve, Buckley Bay

Good for very wet sites

Abundant moisture allows good growth

Initiates succession

Live smiles in 2005

Looking face on…

Red-osier Dogwood doing well

January 2009

January 2009
Western Red Cedar naturally established

Harvey Creek, near Quesnel

North Vancouver

Fisher Creek, near Chetwynd