defining ecological corridors · the minimum space needed to accommodate the fluvial processes and...

Washington Salomon Recovery Conference 2019

Defining ecological corridors (a tool for salmon recovery assessment, planning, and process-based restoration design)

Tim Abbe, Susan Dickerson-Lange and Jennifer O’NealNatural Systems Design

Washington Salomon Recovery Conference 20191Abbe et al. 2016

Habitat forms in a Spatial and Temporal DomainSufficient space is essential to accommodate natural processesRestoring fluvial ecosystems requires sufficient space


How much space does a river need?

Washington Salomon Recovery Conference 20193Halawa Stream, O’ahu

It is very expensive –both economically and environmentally

Marin County, CA

from a traditional flood conveyance perspective, not much


Hanaford 2D - Straightened Section

Looking DS

Distance (ft)580560540520500480460440420400380360340320300280260240220200180160140120100806040200

Elev

ation

(ft)

209.6

209.4

209.2

209

208.8

208.6

208.4

208.2

208

207.8

207.6

207.4

207.2

207

206.8

206.6

206.4

206.2

Leveed Ditch – Hanaford Creek, Chehalis Basin

2100 ft

2100 ft20 ft

1% of natural domain


Constraining rivers doesn’t always go well

Walla Walla River near Milton-Freewater, OR

1% of natural corridor


From a habitat perspective, how much space does a river need?

Not nearly enough?

More than enough?


A need for policy protecting habitat Flood inundation

hazards (FEMA FIRMs)

Erosion hazards (State CMZ delineations)

Ecological Corridor: space to accommodate & sustain habitat forming processes

Current corridors are opportunistic

corr

idor

deve

lopm

ent


Ecological Corridor Definition:The minimum space needed to accommodate the fluvial processes and habitat structural elements that create and sustain the site’s natural habitat diversity.

small valley - EC could be entire valley bottom. large valley – EC could be a fraction of the valley


historical conditions: large floodplain

Habi

tat D

iver

sity

Percent of valley width managed as fluvial corridor

Cost

of R

iver

Man

agem

ent

Straightened, leveed channel

Complete valley restoration

Ecol

ogic

al C

orrid

or

High habitat diversity

No habitat diversity

High cost

Low cost

S

Ecological Corridor Basics


large floodplainHa

bita

t Div

ersi

ty (D

)

Percent of valley width managed as fluvial corridor

Straightened, leveed channel

Complete valley

restoration

Ecol

ogic

al C

orrid

or

High habitat diversity

No habitat diversity 100%

S

Large River

Small Stream

Small floodplain

Ecol

ogic

al C

orrid

or

Ecological Corridor Basics


Constraints on a river vary within its basin.

Valley width Existing river

corridor


An EC depends on understanding pre-disturbance conditions

what habitat existed?what formed it?


Habitat Diversity, Quantity, Quality = f(space)

13

8

Alluvial valley

Confined valley

Structural elements


Habitat Formation Depends on Structural Elements

Big trees directly influence habitat complexity

A loss of big trees leads to a simplification

Willamette 1854 Willamette 1967

Riparian forests, geology and human structures (roads, levees, bridges) influence formative processes over variable spatial and temporal scales


Wood influences vertical and horizontal scales

cm kmsubstrate & cover

Sub-reachBedforms & gradients

Reachplanform & floodplain

992

994

996

998

1000

1002

1004

0 25 50 75 100 125 150 175 200 225 250

Distance (m)

Rela

tive

Elev

atio

n (m

)

Alta Creek Floodplain, Queets Basin, WA

Wood dominated floodplain

Chart1

0

10

25

33

35

36

39.5

41.5

43.5

44.5

45.3

45.4

45.9

46.1

46.9

50.9

51.8

53.8

56.8

60.8

61.7

64.7

65.7

68.7

70.7

72.7

82.7

92.7

102.7

104.7

106.7

108.7

110.7

112.7

114.7

115.2

117.2

119.2

121.2

122.4

125.4

126.4

127.4

128.4

131.4

132.4

134.4

136.4

136.9

137.9

142.4

143.4

144.4

147.4

148.4

151.4

165.4

170.4

174.4

177.4

188.4

192.4

193.4

198.4

199.4

202.4

206.4

207.4

209.4

212.4

216.4

218.4

220.4

222.4

223.4

228.4

233.4

245.4

251.4

Distance (m)

Relative Elevation (m)

999

997.9

998

997.9

997.9

998.8

999

999.1

999.15

999.2

996.4

996.2

996.2

996.1

996.1

995.8

998.1

998.4

998.45

998.5

998.4

998.4

997

997.2

997.4

997.5

997.61

997.4

997.55

997.52

997.46

997.3

996.9

997.1

997.3

999.8

999.8

999.85

999.8

999.8

999.8

1000.8

1001.1

1001

1000.9

1000.85

1000.85

1000.7

1000

999.54

999.55

999.4

994.1

994.3

994.8

994.9

994.8

994.3

994.4

999.1

998.8

998.5

997.5

997.5

998.7

998.8

998.7

995.6

995.7

996.6

996.7

996.4

996

996

1001.4

1001.5

1001.5

1001.4

1001.6

Sheet1

relative

Staelevation

0999

10997.9

25998

33997.9

35997.9

36998.8

39.5999

41.5999.1

43.5999.15

44.5999.2

45.3996.4

45.4996.2

45.9996.2

46.1996.1

46.9996.1

50.9995.8

51.8998.1

53.8998.4

56.8998.45

60.8998.5

61.7998.4

64.7998.4

Figure 3B65.7997

68.7997.2

70.7997.4

72.7997.5

82.7997.61

92.7997.4

102.7997.55

104.7997.52

106.7997.46

108.7997.3

110.7996.9

112.7997.1

114.7997.3

115.2999.8

117.2999.8

119.2999.85

121.2999.8

122.4999.8

125.4999.8

126.41000.8

127.41001.1

128.41001

131.41000.9

132.41000.85

134.41000.85

136.41000.7

136.91000

137.9999.54

142.4999.55

143.4999.4

144.4994.1

147.4994.3

148.4994.8

151.4994.9

165.4994.8

170.4994.3

174.4994.4

177.4999.1

188.4998.8

192.4998.5

193.4997.5

198.4997.5

199.4998.7

202.4998.8

206.4998.7

207.4995.6

209.4995.7

212.4996.6

216.4996.7

218.4996.4

220.4996

222.4996

223.41001.4

228.41001.5

233.41001.5

245.41001.4

251.41001.6

Sheet1

Distance (m)

Relative Elevation (m)


Wood can change channel morphology


Unconstrained

Abbe 2016

Increased morphologic complexity occupies more space

Constrained levee reach

White River, King County


Ecological Corridor AtlasProtocol completed for Skookumchuck Watershed


Ecological Corridor AtlasSkookumchuck Watershed


Current conditions

Skookumchuck


Relative Elevation Mapping (REM)


4 ft

4 ft

Historic Channel Incision


Detail Next Slide

Centralia

Historic Conditions: GLO Mapping

Distance alongSection Line1 chain = 66 feet

Traverse from E to W

Primary Channel

Slough Channel

Another Slough

Plat Map Field Notes


Current conditions

Skookumchuck


“Enter Skookumchuck bottom”

“Intersect Left Bankof the Skookumchuck,100 links (66 ft) wide,Course S 30° W”

“Enter a Slough, Course SE”1 chain (66 ft) wide

“Slough,100 links (66 ft) wideCourse N & S”

“Leave Skookumchuck bottomand enter prairie”

Field notes document primary channel plus two additional slough channels of equal width. Not shown in plat maps… Evidence of anabranching channel pattern

Historic Conditions: GLO Mapping


“Enter Skookumchuck bottom”

“Intersect Left Bankof the Skookumchuck,100 links (66 ft) wide,Course S 30° W”


“Slough,100 links (66 ft) wideCourse N & S”

“Leave Skookumchuck bottomand enter prairie”

Old channel covered in fill

Remnant of slough

Overlaying historic on current REM



Historic reconstruction


Delineated EC

Acknowledgements: Office of Chehalis Basin Aquatic Species Restoration Plan

Defining ecological corridors �(a tool for salmon recovery assessment, planning, and process-based restoration design)Sufficient space is essential to accommodate natural processesHow much space does a river need?Slide Number 4Leveed Ditch – Hanaford Creek, Chehalis BasinSlide Number 6Slide Number 7A need for policy protecting habitatEcological Corridor Definition:��The minimum space needed to accommodate the fluvial processes and habitat structural elements that create and sustain the site’s natural habitat diversity.Slide Number 10Slide Number 11Slide Number 12Slide Number 13Habitat Diversity, Quantity, Quality = f(space)Habitat Formation Depends on Structural ElementsSlide Number 16Wood can change channel morphologySlide Number 18Ecological Corridor Atlas�Protocol completed for Skookumchuck WatershedEcological Corridor Atlas�Skookumchuck WatershedEcological Corridor Atlas�Skookumchuck WatershedCurrent conditionsSlide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30

defining ecological corridors · the minimum space needed to accommodate the fluvial processes and...

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