URBAN STREAM REHABILITATION

URBAN STREAM URBAN STREAM REHABILITATIONREHABILITATION

TECHNIQUES FOR TECHNIQUES FOR REHABILITATIONREHABILITATION

2. Techniques for rehabilitation 2. Techniques for rehabilitation

Measures to lessen the volume of runoff on the sourceMeasures to lessen the volume of runoff on the source

Natural conditionsNatural conditions

EvapotranspirationEvapotranspiration

InfiltrationInfiltration

10-40%10-40%

Up Up to to 50%50%

Can similar effect be Can similar effect be achieved in urban areas ?achieved in urban areas ?


MEASURESMEASURES


Vegetated roof covers (VRC)Vegetated roof covers (VRC)





MEASURESMEASURES



Porous pavement: AsphaltPorous pavement: Asphalt



Porous pavement: AsphaltPorous pavement: AsphaltInfiltrationInfiltration

RunoffRunoff


MEASURESMEASURES



Porous pavement: AsphaltPorous pavement: Asphalt

Porous pavement: Modular-paving blocksPorous pavement: Modular-paving blocks



Porous pavement: Modular-paving blocksPorous pavement: Modular-paving blocks


Measures to improve the quality ofMeasures to improve the quality of runoffrunoff

MEASURESMEASURES

Grassy vegetative filter Grassy vegetative filter stripsstripsGrassed swalesGrassed swales



Grassed Grassed swalesswales

InflowInflowInflowInflowAttenuation and Attenuation and

conveyanceconveyance

Some interflow and Some interflow and infiltrationinfiltration



MEASURESMEASURES


Constructed wetlandsConstructed wetlands


Measures to improve the quality of runoff Measures to improve the quality of runoff


InflowInflow OutfloOutfloww

Contains a permanent pool of Contains a permanent pool of waterwaterDetention up to three weeksDetention up to three weeks

Attenuation, settlement, biological treatmentAttenuation, settlement, biological treatment

Design for wildlife habitatsDesign for wildlife habitats



MEASURESMEASURES



Wet ponds with extended Wet ponds with extended detentiondetention



InflowInflow

OutfloOutfloww

InfiltratioInfiltrationn

Wet ponds Wet ponds with with extended extended detentiondetention

Dry except during and following stormDry except during and following storm

Detention up to 24 hoursDetention up to 24 hours

Attenuation, settlement of coarse siltsAttenuation, settlement of coarse silts


Measures to control erosion and sedimentationMeasures to control erosion and sedimentation

MEASURESMEASURES

Management of construction sites – Construction Management of construction sites – Construction traffictrafficTemporary runoff diversions and chutesTemporary runoff diversions and chutes

Silt fence and trapping devicesSilt fence and trapping devices

Sediment basinsSediment basins

Hydro seeding and chemical stabilizationHydro seeding and chemical stabilization

Cover crops and temporary mulchesCover crops and temporary mulches


Measures to control erosion and sedimentationMeasures to control erosion and sedimentation

Cabled articulated Cabled articulated block block

“Erosion Control in Florida's Little Wekiva River”

by Mary Brabham and Jeff Cole


Measures to maintain groundwater recharge Measures to maintain groundwater recharge

MEASURESMEASURES

Infiltration berms Infiltration berms

Vegetative infiltration swales with check Vegetative infiltration swales with check dams dams Infiltration basins Infiltration basins

Seepage beds/basins/areas Seepage beds/basins/areas

Gravel filled trenches / Dutch drains Gravel filled trenches / Dutch drains with optional drainage pipe in base with optional drainage pipe in base

Wells, gravity shafts and induced Wells, gravity shafts and induced rechargerecharge


Measures to detain peak flowMeasures to detain peak flow

MEASURESMEASURES

Dry detention Dry detention basinsbasinsWet detention Wet detention basinsbasins


Measures to minimize pollution from sewage Measures to minimize pollution from sewage

MEASURESMEASURES

Combined sewer overflow source Combined sewer overflow source controlcontrolOff-line storage of combined sewageOff-line storage of combined sewage


Measures for urban stream rehabilitation in channel bed Measures for urban stream rehabilitation in channel bed and banks and banks

MEASURESMEASURES

Sills as transverse Sills as transverse structures structures Rough bed ground ramps/ rock ground Rough bed ground ramps/ rock ground rampsrampsBlock rampBlock ramp

RacksRacks

Cobble or gravel linersCobble or gravel liners

Channel reconstruction through transverse structures on the streambed Channel reconstruction through transverse structures on the streambed



Sills as transverse Sills as transverse structures structures




Cobble or gravel linersCobble or gravel liners




MEASURESMEASURES

Branch packingBranch packing

Vegetated slope gridVegetated slope grid

Reed-roll revetment and Reed-roll revetment and biologbiologVegetated rock rip-rapVegetated rock rip-rap

Channel stabilization through stream parallel flow guiding structuresChannel stabilization through stream parallel flow guiding structures

Tiered wall or pilings with bench Tiered wall or pilings with bench plantingsplantings

Double-row wattle palisadeDouble-row wattle palisade

Revetment - Piling revetment, slotted board Revetment - Piling revetment, slotted board revetmentrevetment



Live stakes in existing Live stakes in existing riprapriprap

Protection and stabilization of stream banks Protection and stabilization of stream banks

Salzburger Landesregierung, 2002, p.28



MEASURESMEASURES

Groynes, log cribbing deflectors, and current Groynes, log cribbing deflectors, and current deflectors deflectors Live fascines/ fascine bundles/ sinking fascinesLive fascines/ fascine bundles/ sinking fascines

Brush LayeringBrush Layering

Live willow racks Live willow racks

Brush mattressesBrush mattresses


Wattle fenceWattle fence

Live crib walls (syn. Krainer wall)Live crib walls (syn. Krainer wall)

Log, root wad, and boulder revetmentLog, root wad, and boulder revetment

Vegetated rock gabionsVegetated rock gabions

Live slope gratingLive slope grating



Live Live stakesstakes


Before implementation after sprouting after some months



Measures for urban stream rehabilitation in channel bed Measures for urban stream rehabilitation in channel bed and banks and banks Protection and stabilization of stream banks Protection and stabilization of stream banks


Example classical and bioengineering river Example classical and bioengineering river

rehabilitationrehabilitation



Schematic river section with possible soil-bioengineering measures and zones of water management and riparian

vegetation

Schiechtl & Stern, 2001 p.7



A rehabilitated urban river (Fervença, Bragança, Portugal)

Before

(view from right bank) After

(view from centre of river)

More info…More info…

For more information follow this link:For more information follow this link:


TECHNIQUES FOR TECHNIQUES FOR REHABILITATIONREHABILITATION

Soil - Soil - bioengineeringbioengineering

2. Techniques for rehabilitation: Soil bio-engineering2. Techniques for rehabilitation: Soil bio-engineering

Soil bio-engineeringSoil bio-engineering

Soil bioengineering structures combine Soil bioengineering structures combine living plants and dead materials as living plants and dead materials as stones, timber, geotextiles etc. in stones, timber, geotextiles etc. in manifold ways.manifold ways.

The Rehabilitation of urban rivers The Rehabilitation of urban rivers nowadays represents a revival of these nowadays represents a revival of these techniques, that were used since many techniques, that were used since many centuries for stabilizing river banks. centuries for stabilizing river banks.

Examples of urban watercoursesExamples of urban watercourses


Shootings of a fascine wall of 15 months age Source: Gerstgraser, 1998,

p.149

Brook with fascines and timber walls Source: Salzburger

Landesregierung, 2002, p.26

Alterbach, Salzburg: Urban landscape design accounting for ecological integrity Source: Salzburger Landesregierung, 2002, p.14

Source: Salzburger Landesregierung, Fachabteilung 6/6, Wasserwirtschaft (2002): Lebensraum Stadtbach p.13

HQ100

Summer Mean Water Level

HQ100

Summer Mean Water Level

Urban river regulation in former times

Contemporary urban river regulation

Example for a Example for a river cross section river cross section using soil bio-using soil bio-engineering engineering techniquestechniques


Advantages of soil bio-engineering Advantages of soil bio-engineering techniquestechniques


Methods & techniques may have positive Methods & techniques may have positive effects oneffects on

The cityThe cityThe riverThe riverThe peopleThe people

Advantages in terms of sustainability Advantages in terms of sustainability issues concern issues concern

Ecological aspectsEcological aspectsEconomical aspectsEconomical aspectsSocial aspectsSocial aspects

In particular, these positive effects are…In particular, these positive effects are…

Technical Bank protection from water erosion during floods Slope protection from rain, wind or frost erosion Increasing stability due to a soil-root bond Ecological Enhancing habitat conditions by reducing extremes of

temperature and moisture Improved soil water balance by drainage, detention and

evapotranspiration Soil enhancement due to humus formation Creation of habitats Protection from wind and radiation Water purification Aesthetical Harmonization of technical regulations Pronunciation of river shape Increasing perceived value of the river Economical Decreasing construction and maintenance efforts Benefits for recreation, fishery and ecology

Advantages of soil bio-engineering Advantages of soil bio-engineering techniquestechniques

Source: Schiechtl & Stern, 2001, p.14


Willows – most important plantsWillows – most important plants

Young willows (Young willows (SalixSalix species) play an outstanding role due species) play an outstanding role due to their ability to stabilize river banks during floods and a to their ability to stabilize river banks during floods and a quick plant development. quick plant development.


Live stakes before implementation, after sprouting and after some months Source: Salzburger Landesregierung, 2002, p.28

Juvenile, flexible plants can reversibly bend stem and Juvenile, flexible plants can reversibly bend stem and branches under high hydraulic loads, which reduces flow branches under high hydraulic loads, which reduces flow resistance and prevents soil erosion.resistance and prevents soil erosion.

Summarizing considerationsSummarizing considerations

Available space is a pre-requirement for soil bio-Available space is a pre-requirement for soil bio-engineering methods. Numerous techniques, successfully engineering methods. Numerous techniques, successfully applied on rural rivers can be used then.applied on rural rivers can be used then.

The higher the urban spatial, technical and environmental The higher the urban spatial, technical and environmental constraints, the higher the necessary maintenance constraints, the higher the necessary maintenance activities or trade-offs in planning soil bio-engineering activities or trade-offs in planning soil bio-engineering measures.measures.

Within these boundaries, constructions with living plants Within these boundaries, constructions with living plants provide contemporary alternatives to conventional hard provide contemporary alternatives to conventional hard regulations. They may also bring numerous economical regulations. They may also bring numerous economical and intangible benefits. But finally, plants cannot replace and intangible benefits. But finally, plants cannot replace allall concrete structures. concrete structures.


Final ExampleFinal Example


The new Wien River in Vienna, Austria

An example for urban river rehabilitation accounting for multiple criteria.

Flood retention reservoirs, walk and bike lanes and soil bio – engineering measures in the riverbed

Source: URBEM / IWHW - BOKU (2003)

ReferencesReferences

We gratefully thank figure owners for their kind photo donations.We gratefully thank figure owners for their kind photo donations.


Gerstgraser, C. (1998): Ingenieurbiologische Bauweisen an Fliessgewässern. Grundlagen zu Bau, Belastbarkeiten und Wirkungsweisen. Dissertationen der Universität für Bodenkultur, Wien, Band 52. Österreichischer Kunst- und Kulturverlag. Wien 2000

Salzburger Landesregierung, Fachabteilung 6/6, Wasserwirtschaft (2002): Lebensraum Stadtbach. Alterbach, Söllheimer Bach

Schiechtl, H.M., Stern, R (2002): Naturnaher Wasserbau. Anleitung für ingenieurbiologische Bauweisen. Ernst & Sohn, Berlin

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URBAN STREAM REHABILITATION