Planning for Flood Resilient and Fish Friendly Road-Stream ... · From Appalachian Trail in Falls Village, looking toward Berkshires Photo: Bill Wakely . Morning mist Kent, CT . Presentation

Planning for Flood Resilient and Fish Friendly Planning for Flood Resilient and Fish Friendly RoadRoad--Stream Crossings Stream Crossings in CT’s in CT’s Northwest Northwest Hills Hills

Mike Jastremski, CFM

Watershed Conservation Director

Presentation OutlinePresentation Outline

•• Project area Project area

•• Climate threatsClimate threats

•• Field assessmentField assessment

•• Modelling flood vulnerability Modelling flood vulnerability

•• Setting prioritiesSetting priorities

•• Designing replacement projectsDesigning replacement projects

•• Integrating with local planningIntegrating with local planning

CT

NY

MA

HVA covers the entire Housatonic watershed:

• 149 main-stem miles • Roughly 4,200 tributary miles

Riverside in Kent

CT

NY

MA


• The Housatonic River: 149 miles long

• Vertical drop of 1,430 feet • 83 towns in 3 states

…and emptying into Long Island Sound at Stratford and Milford Point, CT

CT

NY

MA


• The Housatonic River: 149 miles long

• Vertical drop of 1,430 feet • 3 states and 83 towns • 1,948 square miles (1.2 million acres)

Housatonic River Valley, Sharon/Cornwall

From Appalachian Trail in Falls Village, looking toward Berkshires Photo: Bill Wakely

Morning mist Kent, CT




•• Field assessmentField assessment-- identify barriersidentify barriers

•• Model flood vulnerability Model flood vulnerability \\

•• Set prioritiesSet priorities

•• Design replacement projectsDesign replacement projects

•• Integrate with local planningIntegrate with local planning

Climate Threats: More RainClimate Threats: More Rain

July 2013 - Sharon, CT Source: Litchfield

County Times

Climate Threats: More RainClimate Threats: More Rain

Increase in polluted runoff o Problems with stormwater runoff we’re used

to…

Climate Threats: Water QualityClimate Threats: Water Quality

… and pollution inputs from major floods that we’re not as familiar with…


Bigger floods = stream instability o Increased erosion


Climate Threats: Rising TemperaturesClimate Threats: Rising Temperatures

Increasing water temperatures, contracting cold-water habitat

Climate Threats: HabitatClimate Threats: Habitat

Importance of MovementImportance of Movement

ReproductionReproduction

Daily and seasonal Daily and seasonal

Changes in habitatChanges in habitat

Genetic diversityGenetic diversity

ColonizationColonization

Movement is Key to Movement is Key to

AdaptationAdaptation

Roads and StreamsRoads and Streams

Fragmentation Fragmentation

Prevents AdaptationPrevents Adaptation

Undersized Culverts = Undersized Culverts =

More Flood Damage More Flood Damage

Dams Dams

Sub-standard

Culverts

Sub-standard

Culverts

Housatonic

streams in CT

Dams

(not comprehensive!)

Roads and railroads

Road-stream

crossings

Dams and

crossings

Respond to climate threats and scale of barrier Respond to climate threats and scale of barrier

problem:problem:

•• Identify replacement projects that both reduce Identify replacement projects that both reduce

flood risk and reconnect important habitatflood risk and reconnect important habitat

•• BBuild local capacity to take advantage of uild local capacity to take advantage of

every opportunity to replace problem culvertsevery opportunity to replace problem culverts

Project GoalsProject Goals

TownTown--Scale Scale Management PlansManagement Plans

• 7 towns

• Evaluate flood risk and

conservation value


• Create town-specific

Road-Stream Crossing

Inventory docs

• Use Inventory to set

priorities





•• Modelling flood vulnerabilityModelling flood vulnerability

•• Town prioritization workshopsTown prioritization workshops



Field AssessmentField Assessment


Stream Shape: CrossStream Shape: Cross--sectionsection

Stream Shape: PatternStream Shape: Pattern

•• Pattern is a stream’s shape from abovePattern is a stream’s shape from above

•• Placement of features like meander bends, pools and rifflesPlacement of features like meander bends, pools and riffles

Adapted from North Carolina Cooperative

Extension Service, 1999

Stream Shape: SlopeStream Shape: Slope

Excessive Velocities Excessive Velocities


Inlet Drop Inlet Drop

Scour Hole Scour Hole

Outlet Drop

(Perching)

Outlet Drop

(Perching)

Tail Water

Armoring

Tail Water

Armoring

Insufficient Water

Depth

Insufficient Water

Depth

ResultsResults

• Since 2013 900 +

crossings assessed in project area

• Barriers common and

widespread

• Many barrier crossings managed by towns with limited resources

Barrier Evaluation Number Percentage

Severe barrier 151 25%

Significant barrier 61 10%

Moderate barrier 144 24%

Minor Barrier 206 34%

Insignificant Barrier 42 7%

No barrier (full passage)

0 0%

Of 604 assessed

culverts, 356 are

moderate to

severe barriers

Stream Habitat FragmentationStream Habitat Fragmentation

59%!

Dams and

crossings

Fragmentation Fragmentation

Prevents AdaptationPrevents Adaptation









Simulating Flood RiskSimulating Flood Risk

•• How do we predict How do we predict

whether or not this whether or not this

culvert…culvert…

…will flood the road?…will flood the road?

Culvert InletCulvert Inlet

CREST ModelCREST Model

•• HVA is partnering HVA is partnering with UCONNwith UCONN

•• CREST ModelCREST Model

•• Combining the Combining the model with field model with field data, UCONN data, UCONN can simulate can simulate which crossings which crossings will flood the will flood the roadroad

Distributed Variables

Soil Properties

Vegetation Library

Land Cover

Impervious Area

Water Balance Energy Balance

Atmospheric Layer

Canopy Layer

Snow Pack Layer

Surface Soil Layer

Deep Soil Layer

River

discharge (Q)

Interception

Evaportranspiration

Snow Process

Infiltration

Fully Distributed Routing

RunoffET

Hourly MeteorologIc

Variables

climatology

Precipitation

Forc

e

T

W

CalibrationUSGS (Q)

Routing parameters

Remotely Sensed Products

Leaf Area Index

GIS-Terrain

elevation

flow direction

Stream network

Undersized Culverts = Undersized Culverts =

More Flood Damage More Flood Damage

















Design PhaseDesign Phase

•• Leverage limited Leverage limited

fundingfunding

•• Enormous scale of Enormous scale of

problemproblem

•• Build capacity at Build capacity at

municipal levelmunicipal level

Stream Simulation DesignStream Simulation Design

RoadRoad--stream crossing design that mimics the natural stream stream crossing design that mimics the natural stream

channel through a structure, as if the crossing didn’t exist.channel through a structure, as if the crossing didn’t exist.

Stream Shape: CrossStream Shape: Cross--sectionsection

Stream Shape: PatternStream Shape: Pattern

•• Pattern is a stream’s shape from abovePattern is a stream’s shape from above

•• Placement of features like meander bends, pools and rifflesPlacement of features like meander bends, pools and riffles

Adapted from North Carolina Cooperative

Extension Service, 1999

Stream Shape: SlopeStream Shape: Slope

Width of a Stream

Simulation Design

structure is spans

the natural bed

and banks.



Minimizes stream skew


Substrate designed to replicate natural streambed – allowing for mobility and dynamic response to the need for additional capacity.


Flood ResiliencyFlood Resiliency

Provides sufficient

hydraulic capacity

and passage of

debris

Flood ResiliencyFlood Resiliency

Reduces the

likelihood of

clogging, upstream

ponding, and road

overtopping.

Economic BenefitsEconomic Benefits

Lower longLower long--term cost over the lifespan of the structure as term cost over the lifespan of the structure as

compared to an “in kind” replacement:compared to an “in kind” replacement:

••Less maintenanceLess maintenance

••Less repairLess repair

••Reduced flood damageReduced flood damage


These cost saving These cost saving

factors will become factors will become

more and more more and more

relevant as storms relevant as storms

increase in both increase in both

intensity and intensity and

frequency due to frequency due to

climate change.climate change.


Stream Sim = New Stream Sim = New

Funding OpportunitiesFunding Opportunities


Stream Simulation Design is good for everyone:Stream Simulation Design is good for everyone:

•• Economic benefits for local communitiesEconomic benefits for local communities

•• HHabitat improvement for native speciesabitat improvement for native species

•• Resilient infrastructureResilient infrastructure










Combine:

• Inventory

• Ranking

• Conceptual designs

• Supporting

information

• Adopt as part of

Hazard Mitigation

Plan

Partners, Funders and AdvisorsPartners, Funders and Advisors

Town of Cornwall, CT

Housatonic River NRD Trustees

Documents

Planning for Flood Resilient and Fish Friendly Road-Stream ... · From Appalachian Trail in Falls Village, looking toward Berkshires Photo: Bill Wakely . Morning mist Kent, CT . Presentation