The Humber Estuary is recognised as one of the most important estuaries for wildlife in Europe and is protected under national nature conservation legislation. As part of the regulations, any habitat lost through human activity must be replaced as compensatory habitat. The Outstrays Managed Realignment Scheme seeks to rebalance the impact of rising sea levels and new flood risk management around the Humber by creating new, ecologically valuable habitats on former arable land.

What is managed realignment?
Managed realignment is a sustainable coastal management strategy. In this project, the managed realignment approach consisted of three phases. The first phase was to construct an area of freshwater habitat and higher roosting ground adjacent to the proposed new intertidal habitat. The second phase involved constructing a new flood embankment further inland from an existing one, and creating a variety of habitats, including tidal channels in the area between the old and new embankments. The final phase was to breach the old flood embankment, allowing a controlled flow of tidal water into the area to enable the transition of the arable land to mudflat and saltmarsh.

How were we involved?
Led by our colleagues at JBA Bentley, this large-scale habitat creation scheme saw close collaboration between our engineering and environmental teams. Due to the highly ecologically sensitive nature of the area, we initially supported the design phase by conducting a range of ecological surveys. We created a record of the site's existing habitats and species, and were able to make recommendations and propose mitigation strategies to limit the ecological impact of the work.

A key element of our involvement was developing integrated working strategies to ensure the site's ecological constraints were managed effectively. We worked collaboratively to create exclusion zones and restricted 'working windows' (from March to October each year), and adopted species-specific mitigation strategies for Marsh Harriers, Water Voles, Badgers and reptiles, among others. One such mitigation strategy involved an innovative technique for relocating Sea Aster Mining Bees. The translocation involved using sand-filled boxes as artificial nesting sites, enabling the bees to be moved into new habitats before they emerged from hibernation.