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URBAN STREAM REHABILITATION

URBAN STREAM REHABILITATION. TECHNIQUES FOR REHABILITATION. Measures to lessen the volume of runoff on the source. Evapotranspiration. 10-40%. Can similar effect be achieved in urban areas ?. Infiltration. Up to 50%. Natural conditions. 2. Techniques for rehabilitation.

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URBAN STREAM REHABILITATION

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  1. URBAN STREAM REHABILITATION

  2. TECHNIQUES FOR REHABILITATION

  3. Measures to lessen the volume of runoff on the source Evapotranspiration 10-40% Can similar effect be achieved in urban areas ? Infiltration Up to 50% Natural conditions 2. Techniques for rehabilitation

  4. Measures to lessen the volume of runoff on the source MEASURES Vegetated roof covers (VRC) 2. Techniques for rehabilitation

  5. Measures to lessen the volume of runoff on the source Vegetated roof covers (VRC) 2. Techniques for rehabilitation

  6. Measures to lessen the volume of runoff on the source MEASURES Vegetated roof covers (VRC) Porous pavement: Asphalt 2. Techniques for rehabilitation

  7. Measures to lessen the volume of runoff on the source Runoff Infiltration Porous pavement: Asphalt 2. Techniques for rehabilitation

  8. Measures to lessen the volume of runoff on the source MEASURES Vegetated roof covers (VRC) Porous pavement: Asphalt Porous pavement: Modular-paving blocks 2. Techniques for rehabilitation

  9. Measures to lessen the volume of runoff on the source Porous pavement: Modular-paving blocks 2. Techniques for rehabilitation

  10. Measures to improve the quality ofrunoff MEASURES Grassy vegetative filter strips Grassed swales 2. Techniques for rehabilitation

  11. Measures to improve the quality ofrunoff Grassed swales Inflow Inflow Attenuation and conveyance Some interflow and infiltration 2. Techniques for rehabilitation

  12. Measures to improve the quality ofrunoff MEASURES Grassy vegetative filter strips Grassed swales Constructed wetlands 2. Techniques for rehabilitation

  13. Measures to improve the quality of runoff Constructed wetlands Contains a permanent pool of water Detention up to three weeks Attenuation, settlement, biological treatment Design for wildlife habitats Inflow Outflow 2. Techniques for rehabilitation

  14. Measures to improve the quality ofrunoff MEASURES Grassy vegetative filter strips Grassed swales Constructed wetlands Wet ponds with extended detention 2. Techniques for rehabilitation

  15. Measures to improve the quality ofrunoff Wet ponds with extended detention Dry except during and following storm Detention up to 24 hours Attenuation, settlement of coarse silts Inflow Outflow Infiltration 2. Techniques for rehabilitation

  16. Measures to control erosion and sedimentation MEASURES Management of construction sites – Construction traffic Temporary runoff diversions and chutes Silt fence and trapping devices Sediment basins Hydro seeding and chemical stabilization Cover crops and temporary mulches 2. Techniques for rehabilitation

  17. Measures to control erosion and sedimentation Cabled articulated block “Erosion Control in Florida's Little Wekiva River” by Mary Brabham and Jeff Cole 2. Techniques for rehabilitation

  18. Measures to maintain groundwater recharge MEASURES Infiltration berms Vegetative infiltration swales with check dams Infiltration basins Seepage beds/basins/areas Gravel filled trenches / Dutch drains with optional drainage pipe in base Wells, gravity shafts and induced recharge 2. Techniques for rehabilitation

  19. Measures to detain peak flow MEASURES Dry detention basins Wet detention basins 2. Techniques for rehabilitation

  20. Measures to minimize pollution from sewage MEASURES Combined sewer overflow source control Off-line storage of combined sewage 2. Techniques for rehabilitation

  21. Measures for urban stream rehabilitation in channel bed and banks Channel reconstruction through transverse structures on the streambed MEASURES Sills as transverse structures Rough bed ground ramps/ rock ground ramps Block ramp Racks Cobble or gravel liners 2. Techniques for rehabilitation

  22. Measures for urban stream rehabilitation in channel bed and banks Channel reconstruction through transverse structures on the streambed Sills as transverse structures 2. Techniques for rehabilitation

  23. Measures for urban stream rehabilitation in channel bed and banks Channel reconstruction through transverse structures on the streambed Cobble or gravel liners 2. Techniques for rehabilitation

  24. Measures for urban stream rehabilitation in channel bed and banks Channel stabilization through stream parallel flow guiding structures MEASURES Branch packing Revetment - Piling revetment, slotted board revetment Double-row wattle palisade Vegetated slope grid Reed-roll revetment and biolog Vegetated rock rip-rap Tiered wall or pilings with bench plantings 2. Techniques for rehabilitation

  25. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks Live stakes in existing riprap Salzburger Landesregierung, 2002, p.28 2. Techniques for rehabilitation

  26. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks MEASURES Groynes, log cribbing deflectors, and current deflectors Live fascines/ fascine bundles/ sinking fascines Brush Layering Live willow racks Brush mattresses Wattle fence Live crib walls (syn. Krainer wall) Live slope grating Vegetated rock gabions Log, root wad, and boulder revetment 2. Techniques for rehabilitation

  27. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks Live stakes Before implementation after sprouting after some months Salzburger Landesregierung, 2002, p.28 2. Techniques for rehabilitation

  28. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks Example classical and bioengineering river rehabilitation Salzburger Landesregierung, 2002, p.13 2. Techniques for rehabilitation

  29. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks Schematic river section with possible soil-bioengineering measures and zones of water management and riparian vegetation Schiechtl & Stern, 2001 p.7 2. Techniques for rehabilitation

  30. Measures for urban stream rehabilitation in channel bed and banks Protection and stabilization of stream banks A rehabilitated urban river (Fervença, Bragança, Portugal) Before (view from right bank) After (view from centre of river) 2. Techniques for rehabilitation

  31. More info… For more information follow this link: 2. Techniques for rehabilitation

  32. TECHNIQUES FOR REHABILITATION Soil - bioengineering

  33. Soil bio-engineering Soil bioengineering structures combine living plants and dead materials as stones, timber, geotextiles etc. in manifold ways. The Rehabilitation of urban rivers nowadays represents a revival of these techniques, that were used since many centuries for stabilizing river banks. 2. Techniques for rehabilitation: Soil bio-engineering

  34. Examples of urban watercourses Brook with fascines and timber walls Source: Salzburger Landesregierung, 2002, p.26 Shootings of a fascine wall of 15 months age Source: Gerstgraser, 1998, p.149 Alterbach, Salzburg: Urban landscape design accounting for ecological integrity Source: Salzburger Landesregierung, 2002, p.14 2. Techniques for rehabilitation: Soil bio-engineering

  35. Example for a river cross section using soil bio-engineering techniques Source: Salzburger Landesregierung, Fachabteilung 6/6, Wasserwirtschaft (2002): Lebensraum Stadtbach p.13 2. Techniques for rehabilitation: Soil bio-engineering

  36. Advantages of soil bio-engineering techniques • Methods & techniques may have positive effects on • The city • The river • The people • Advantages in terms of sustainability issues concern • Ecological aspects • Economical aspects • Social aspects • In particular, these positive effects are… 2. Techniques for rehabilitation: Soil bio-engineering

  37. Advantages of soil bio-engineering techniques Source: Schiechtl & Stern, 2001, p.14 2. Techniques for rehabilitation: Soil bio-engineering

  38. Willows – most important plants Young willows (Salix species) play an outstanding role due to their ability to stabilize river banks during floods and a 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 branches under high hydraulic loads, which reduces flow resistance and prevents soil erosion. 2. Techniques for rehabilitation: Soil bio-engineering

  39. Summarizing considerations Available space is a pre-requirement for soil bio-engineering methods. Numerous techniques, successfully applied on rural rivers can be used then. The higher the urban spatial, technical and environmental constraints, the higher the necessary maintenance activities or trade-offs in planning soil bio-engineering measures. Within these boundaries, constructions with living plants provide contemporary alternatives to conventional hard regulations. They may also bring numerous economical and intangible benefits. But finally, plants cannot replace all concrete structures. 2. Techniques for rehabilitation: Soil bio-engineering

  40. Final 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) 2. Techniques for rehabilitation: Soil bio-engineering

  41. References 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 We gratefully thank figure owners for their kind photo donations. 2. Techniques for rehabilitation: Soil bio-engineering

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