rc401 construction jennings intro

Stream Restoration Project Implementation

Greg Jennings, PhD, PEProfessor & Extension SpecialistBiological & Agricultural EngineeringNorth Carolina State [email protected]

Body of water with a current, confined within a bed and streambanks

Synonyms: brook, beck, burn, creek, crick, kill, lick, rill, river, syke, bayou, rivulet, run

Streams are conduits in the water cycle and also important habitats

What is a Stream?

Photo Credit: Eve Brantley, Auburn University

• Channel (bed & banks)• Floodplain• Water• Sediment• Plants & animals

A Stream is a System:


Stream Functions1. Transport water

2. Transport sediment

3. Habitat (aquatic & terrestrial)

4. Recreation & aesthetics

5. Safe Water Supply

What Makes a Stream Healthy?• Bed stability & diversity

• Sediment transport balance

• In-stream habitat & flow diversity

• Bank stability (native plant roots)

• Riparian buffer (streamside forest)

• Active floodplain

Bed Stability & Diversity• Appropriate size sediments

to resist shear stress

• Riffle/Pool sequences in alluvial streams

• Step/Pool sequences in high-gradient streams


Sediment Transport Balance• Minor erosion & deposition

• Alluvial bars and benches

• Sufficient stream power to avoid aggradation

PoolRoots Wood

Leaf Pack

RiffleRocks

In-stream Habitat & Flow Diversity

Plants

Overhanging Bank

Bank Stability• Dense native

plant roots

• Low banks with low stress

Riparian Buffer (Streamside Forest)• Diverse native plants

• Food and shade

Active Floodplain• Regular (every year) flooding to relieve stress

• Riparian wetlands

• Stormwater retention & treatment

Why Restoration?

• Water quality impairments

• Habitat loss

• Ecosystem degradation

• Land loss

• Safety concerns

• Infrastructure damage

• Flooding

• Aesthetics

Why are Streams NOT Healthy?• Straightening

• Dredging

• Floodplain filling

• Sedimentation

• Stormwater

• Utilities

• Culverts & bridges

• Buffer removal

• Disdain & neglect

“activities that initiate or accelerate the recovery of ecosystem health, integrity, and sustainability” (SER, 2004)

Ecosystem Restoration

1. design of an ecological river restoration project should be based on a specified guiding image of a more dynamic, healthy river that could exist at the site

2. river’s ecological condition must be measurably improved

3. river system must be more self-sustaining and resilient to external perturbations so that only minimal follow-up maintenance is needed

4. during the construction phase, no lasting harm should be inflicted on the ecosystem

5. both pre- and post-assessment must be completed and data made publicly available

Standards for ecologically successful river restorationPalmer et al., Journal of Applied Ecology, 2005, 42, 208–217

Habitats

Water quality

Natural flow regimes

Recreation & aesthetics

Outcomes of Ecosystem Restoration

High-quality “reference” streams serve as design templates

Natural Stream Channel Stability(from Leopold)

• River has a stable dimension, pattern and profile• Maintains channel features (riffles, pools, steps)• Does not aggrade (fills) or degrade (erodes)

Restoration Components

1. Channel morphology & floodplain connection

2. In-stream structures

3. Streambank stabilization

4. Riparian buffers

5. Stream crossings

6. Stormwater/watershed management

7. Monitoring & maintenance

8. Public access & education

• Dimension (bankfull & flood flow)• Pattern (meander)• Profile (bed profile)• Floodplain connection

1. Channel Morphology & Floodplain Connection

2005 NCSU Rocky Branch 2006

2008 NCSU Rocky Branch

Bankfull Stage: Water fills the active channel and begins to spread onto the floodplain

Stream Corridor Restoration: Principles, Processes, and Practices. 1998. Federal Interagency Stream Restoration Working Group.

Priority 1

Priority 2

2006 Town Creek Tributary 2007

Priority 1: Raise channel to existing valley and construct new meandering channel

Rain will come during and immediately following construction!

2008 Town Creek Tributary


2008 Purlear Creek 2009

2009 Purlear Creek


2005 South Fork Mitchell River 2006Photo Credits: Darrell Westmoreland, North State Environmental, Inc.

2008 South Fork Mitchell River

2007 Cary Walnut Creek Tributary 2008

Priority 2: Excavate lower floodplain and construct new meandering channel

Photo Credit: David Bidelspach, Stantec, Inc.

2008 Cary Walnut Creek Tributary

2006

NCSU Rocky Branch

2006

2008 NCSU Rocky Branch


2008 Trib to Saugatchee Creek 2008

Wfpa

Wbkf

Entrenchment Ratio = Wfpa / Wbkf = 75/15 = 5

Priority 3. Excavate floodplain benches and add structures to maintain straight channel


NCSU Rocky Branch

2008

Priority 3: Excavate narrow floodplain benches in confined systems

2009 Little Shades Creek 2010

Wfpa

Wbkf

Entrenchment Ratio = Wfpa / Wbkf = 60/38 = 1.6

2. In-Stream Structures (Logs & Rocks)• Streambank protection• Habitat enhancement (pools, aeration, cover)• Grade control• Sediment transport

Boulder Vane (single-arm)

Runaway Truck Ramp

J-Hook Boulder Vane

J-Hook

Boulder Vane

J-Hook Boulder Vane

J-Hook

Log Vane

J-Hook Log Vane

Double Drop J-Hook Log Vane

Multiple Log Vanes

Saugahatchee Creek

2007

2008

Multiple Log Vanes

Saugahatchee Creek

2009 January

2009 JulyPhoto Credit: Dan Ballard, Town of Auburn

Boulder Cross Vane

Double-Drop Boulder Cross Vane

Photo Credit: Darrell Westmoreland, North State Environmental, Inc.

Photo Credit: Darrell Westmoreland, North State Environmental, Inc.


Double-Drop Offset Boulder Cross Vane

Photo Credit: CAWACO RC&D

Double-Drop Offset Boulder Cross Vane

Offset Boulder Cross Vane at a Bridge

Boulder W-Vane

Boulder Double Wing Deflector

Boulder Single Wing Deflector

Constructed Riffle

Z - Vane

Constructed Step-Pool

Constructed Step-Pool + Cross Vane

Habitat Enhancements

• Food sources• Cover• Scour pools• Flow diversity

Pool Maintenance

Successful Structures

• Properly designed and located• Low profile• Constructed to withstand stress• Excellent vegetation

• Temporary matting• Root wads• Bioengineering (living brush mattress)• Armoring

3. Streambank Stabilization

• Biodegradable (coir, jute, excelsior)• Seed and straw UNDER mat• Keep matting relaxed• Key in at top• Stakes: wood or biodegradable plastic

Temporary Matting

Root Wads

10-15 ft tree trunk attached

Streambank Bioengineering:


Integrating living woody and herbaceous materials to increase strength and structure of the soil (i.e. increase critical shear stress)

Brush Mattress

live cuttings of silky willow in dormant season

2007 October

2009 August

Newland Kentucky Creek

bioengineering with black willow cuttings

4. Riparian Buffer (Streamside Forest)• Temporary ground covers• Permanent grasses• Wetland plants• Shrubs and trees

Grasses: temporary & permanent ground covers (wheat, rye, millet, switchgrass)

Wetland plants: transplants, containers, seed (rushes, sedges, flowering plants)

Live Stakes(willows, dogwoods,

elderberry, birch, ninebark, etc)

Transplants, Bare roots, & Containers

5. Stormwater Management

• Energy dissipation• Floodplain retention• Channel protection• Water quality treatment

Floodplain stormwater retention and treatment

6. Stream Crossings

• Aquatic organism passage• Minimize geomorphic impacts• Pass flood flows

7. Monitoring & Maintenance• Projects are most vulnerable early• Natural adjustments to hydrologic &

habitat conditions

8. Public Access & Education• Greenways & paths• Signs• Tours

Why do Projects Fail?

1. Faulty design

2. Faulty construction

3. Poor vegetation

4. Constraints in valley

5. Watershed conditions

rc401 construction jennings intro

Technology

stream healthy

stream habitat flow

bed stability diversity

eve brantley

water cycle

auburn university

channel bed banks

active floodplain