Intertidal Planting Solution on River Thames

Royal Wharf Rock Roll Coir Roll sandwichRoyal Wharf reed bed just installedReedbeds established in Rock Roll and Coir Roll sandwichSediment accretion in Rock Rolls which ensures they are no longer visible Inundated reed bed at high tideRoyal Wharf intertidal reed bed solution - 2 years after installation
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Sediment accretion in Rock Rolls which ensures they are no longer visible

Salix were approached for design support on an intertidal project on the Thames, just shy of the Thames Tidal Barrier.

The Salix system of a Rock Rolls /Pre-established Coir Rolls sandwich was adopted as the design.

This solution was able to address the technical concerns of the Environment Agency and has created an effective habitat and environmental service. Two years after the installation the reed bed is flourishing.

The brief was
  • The plants must cope with brackish water
  • A level bed with alternating dry periods or sudden inundation
  • Allow for a rush of water, and often wave energy that reflects back off the vertical walls, creating a zone of extra turbulence
  • When emptying, the plants, the sediment accreted and the base growing medium must all be retained within the bay
  • Provide a long-term reed bed solution as a potential habitat

A novel solution to a terrace intertidal habitat

In August 2015 the dormant reeds pre-established in Coir Rolls were installed alongside the Rock Roll component.

The Common Reed Phragmites australis is tolerant of brackish water and frequent inundation. The reeds were established in a Coir Roll off site by ourselves at our wetland nursery in Norfolk.

The reed plants will go on to establish further roots into in the base material and also colonise the interstices of the adjacent Rock Rolls. By colonising the Rock Rolls the reed population now has an overall long-term stability against pulses of high energy turbulence created by the influx and retreat of the tidal waters.

The combination of permanent Rock Rolls and biodegradable Coir Rolls will provide a range of sediment traps that will benefit the biodiversity of the habitat in the future.

And the result two years on is one to be proud of, the reeds have filled the tray and the habitat is firmly established for the benefit of a wide range of wildlife.

Details

Name: Royal Wharf Intertidal Terrace
Client: Oxley Developments
Location: Royal Wharf, North Woolwich Rd, London
Category: Intertidal Rivers, Rivers & Water Courses, Wetland Habitat Creation

Case Study