Lessons Learned from 20 Years of Managed Realignment and Regulated Tidal Exchange in the UK

In certain coastal and estuarine locations, the best and most sustainable way to enhance flood protection is to realign the primary sea defences in a landward direction. This typically involves building new sea walls at the back of a site and then either breaching the old wall to fully open up the land to tidal waters (‘managed realignment’ (MR)) or inserting tidal exchange structures such as sluices into the old wall to enable greater control of the new tidal flows (‘regulated tidal exchange’ (RTE)). Alongside sediment recharge, such ‘soft’ engineering measures can be used to respond to sea level rise, improve the cost effectiveness of coastal defences and create new intertidal habitat.  The paper is informed by the authors’ practical experiences, as well as consultation and literature used for the creation and ongoing updating of the Online Managed Realignment Guide (OMReG) database