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10. Restoring the River Camac - Mary-Liz Walshe, DCC

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On 17 and 18 June 2020 the EPA held its National Water Event as an online conference.

This year's theme was 'Restoring our waters'.

This years event was free to attend. It was the EPA's largest water event ever, with over 1250 attending.

To everyone who joined us: thanks for attending; thanks for your probing questions; thanks for your passion; thanks for caring about our waters. We can achieve more working together.

Special thanks to all our presenters and the team who worked behind the scenes to make sure this years conference happened.

For science and stories about water quality in Ireland, check out www.catchments.ie

Published in: Science
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10. Restoring the River Camac - Mary-Liz Walshe, DCC

  1. 1. River Restoration in Dublin City Challenges and Opportunities on the Camac River in the face of flood risk management, urban renewal and climate change Mary-Liz Walshe BA, BAI, MSc, MIEI Project Manager of the Regional Camac Flood Alleviation Scheme (Civil Engineer/Spatial Planner) Dublin City Council Water Framework Directive Office
  2. 2. Introduction to Camac River • Different land uses & Different pressures • 400 buildings at risk from fluvial flooding • Two Local Authorities • Current Status • Key pressures and solutions • NWRM • Natural river = Healthy river = Robust river
  3. 3. • Lengthy culverts • Channelisation • Loss of floodplains, wetlands, riparian corridors • Flood storage and habitats • River processes • Base flow? Camac River Lower Catchment: Hydromorphology
  4. 4. Camac River Mid and Upper Catchments: Hydromorphology • Channel over deepened • Brittas Ponds
  5. 5. Camac River: Hydromorphology • Tackling existing hymo pressures • AND • Avoiding unnecessary new ones
  6. 6. Camac River: Hydromorphology • Challenges and opportunities • Camac Flood Alleviation Study • Maximising existing green space • Rezoning of industrial lands and development control • Camac Greenway • River Restoration Plan • synergies Photo courtesy of the RRC
  7. 7. Camac River Rehabilitation and Flood Alleviation Scheme 2019: Considerations • At risk of not achieving ‘good status’ by 2027 in part due to hydromorphological condition. • Sufficient existing green space to provide floodplain storage and other Hymo NWRM? • Impact of constructing new flood walls and increasing the heights of existing walls? • Lengthy culverts in private lands.
  8. 8. Fishing, Swimming, Canoeing, Nature study, Maintenance Picnic areas, fishing stands, Bird hides Trails, grasslands, picnic areas, Grass Pitches, mostly low-maintenance Retention and detention strategies Buildings, Roads, Cycle-ways, structures Retention and detention structures, drainage systems DWF Normal/ Baseflow Bankfull Max Channel Flow 10 year flood 100 yr Flood ZONE 1 ZONE 2 ZONE 3 ZONE 4 RIVER 2- 6m [from c line] RIVERBANK 6 – 12 m[from c line] FLOODPLAIN [12 – 100m from c line] RIVER VALLEY [floodplain to watershed] WILD NATURAL MANAGED OCCUPIED No Use, Water Access Only Occasional Access Limited Access Universal Access, All uses Emergent Vegetation Herbaceous Vegetation Free Flow C L Erosion Deposition 1m Extracted from Draft Conceptual Framework for Urban River Rehabilitation by Conor Skehan, DIT , 2018. Planning for…..
  9. 9. Need to Plan the Whole Catchment • Instream measures insufficient for WFD Status improvements • Must work to restore all river processes and plan the whole catchment • Need land • Collaboration with OPW, other council departments, local community • Forward planning, RSES
  10. 10. Camac Catchment Analysis Investigating interactions between River Restoration, Climate Change Adaptation, Urban Renewal and Landuse Planning, and Flood Risk Management
  11. 11. Urban Renewal, Flood Risk Management and Climate Change, River Restoration, Nature/Biodiversity... Everybody needs land! So what now? Understanding the river’s condition • Protect what is vulnerable/valuable… • Defining the problems/opportunities Setting priorities Is sufficient suitable land available now? Does the river need more? • Land for natural floodplains, for riparian habitat restoration, (for SuDS retrofit)... Establishing land requirements How can we secure additional land for rivers? Dedicated funding? CPO? Zoning? Different mechanisms Different timescales for delivery Solution delivered in phases? Identifying synergies Achieving a balance: ‘Not here’ or ‘not yet’ Different priorities for different sections?
  12. 12. Higher walls for a growing tourism quarter? Or additional floodplain Storage? Availability of land? Development Pressures Social acceptance/Economy/Amenity
  13. 13. • Greater flows inside M50 • Need additional storage here • Long culverts • Space for natural floodplains, etc? • New thinking on use of public parks? • Prevent new hymo pressures: Guidelines for planning (OPW flood maps) • Opportunities for enhancements? • New Hydromorphology Assessment Methodology (RRC for DCC) • Define and understand the problems
  14. 14. • Future pressures but potential opportunities for NWRM retrofit (LAP’s, URDF’s, rezoning...) • Preserve existing floodplains/riparian zones and reinstate historical ones • Also opportunity to tackle other WFD pressures e.g. buffer zones along roads?
  15. 15. Photo RRC
  16. 16. River Restoration and Greenway Planning for River Camac
  17. 17. Planning a river-friendly greenway Planning A Greenway: Splitting Habitats Planning A Greenway: Habitat ‘Stepping Stones’ Extracted from Draft Conceptual Framework for Urban River Rehabilitation by Conor Skehan, DIT , 2019.
  18. 18. Working Towards a Camac River Restoration Plan
  19. 19. Protection for Future River Restoration through Land Zoning Protecting floodplains and riparian corridors for significantly modified rivers is challenging SuDS retrofit to address particular pressures Need a solid basis for zoning decisions Finding the evidence Hydromorphological Assessment Methodology Biological Condition Surface Water Quality
  20. 20. Wider WFD Considerations and Planning Decisions 1. Morphology • Flooding – flow and storage • Erosion and deposition 2. Water Quality • Assimilative Capacity for discharges • Assimilative capacity for runoff 3. Biodiversity • Habitats & Resources • Flow levels 4. Beneficial Uses • Recreation & Amenities (White water rafting?) • Access & Routes (Greenway?) 1. Identify Issues 2. Assess Capacity 3. Agree Priorities 4. Assign Roles 5. Arrange Implementation Extracted from Draft Conceptual Framework for Urban River Rehabilitation by Conor Skehan, DIT , 2019.
  21. 21. Synopsis • Balance between WFD, Floods Directive... achieving synergies first… • housing, transport, tourism and… healthy living/working environments… climate adaptation • Making room for the river • New zoning objectives for ‘River Protection and Climate Adaptation’? Etc. • Hard-working, multipurpose green space • Change in mind-set! Not wasted land! • When we strip out nature, we make ourselves vulnerable • Importance of forward planning and integrated catchment management planning
  22. 22. Thank you • Email: maryliz.walshe@dublincity.ie

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