Regulated tidal exchange
East Haven Creek (Essex)
Bowers Marsh is a nature reserve managed by the RSPB. It includes a mix of dry and wet grassland, fresh and saline lagoons, intertidal habitat, saltmarsh and arable areas. It was implemented (from sketch drawing to practical completion) over just 22 months.
The tidal exchange that is needed to create the saline lagoon and intertidal fringes is controlled through a relatively large RTE structure. This has a penstock design with three culverts. On the flooding tide water passes through a single culvert, on the ebb it passes through all three.
The inflow pipe was 1000 mm and the two outflow pipes 750 mm. Having three culverts to accommodate an ebb tide might well be more than is really needed but it is valuable that the structure requires relatively little maintenance.
The site excavations across the adjacent freshwater habitats were constrained by the high level of archaeological interest (including red hills) and protected water voles had to be translocated from the area to a suitable receptor site.
There are signs of accretion within the tidal areas. This is evident particularly between the islands within the saline lagoon.