Tidal lagoons have the potential to be used to protect coastal communities and manage and lower the risk of flooding. The lagoon walls provide a more sheltered environment, reducing the risk of overtopping and offering the potential to manipulate water levels at times of surge. By artificially maintaining water levels at low levels, lagoons could also play a part in reducing the risk of flooding from rivers.
The design and location of lagoon walls need to be carefully considered to ensure that they do not increase flood risk elsewhere by altering existing water levels or wave climate – e.g. reflecting waves and potentially causing coastal erosion or flooding in areas that were previously not at risk.