The Wash has been identified as a gap in the national tidal monitoring network. The closest strategic gauges are located at Immingham, within the Humber Estuary to the north and Cromer, on the north Norfolk coast to the east. Due to the relatively complex tidal circulation patterns within The Wash, tidal conditions cannot be accurately predicted by the ports in The Wash, such as King’s Lynn and Boston, using data from the adjacent strategic gauges. In addition to impacts on port operations and navigation within The Wash, this data gap means that both long term mean and extreme sea level predictions, that underpin many policy decisions in Flood and Coastal Erosion Risk Management, cannot be accurately made. This is particularly important for The Wash, which, due to the large extent of low lying hinterland protected by earth embankments, has a high tidal flood risk. This data is also an essential input to international environmental monitoring programmes and international oceanographic studies.
In addition to the 43 strategic tide gauges in the UKTGN, there is a further subgroup of 300 ‘secondary’ gauges used for operational purposes. The Environment Agency has three secondary gauges within The Wash. However all sites are influenced by river flows and are known to dry out during low water on spring tides. They do not, therefore, comply with the ‘Class A’ standards, and do not allow for accurate tidal predictions within The Wash itself.
A Class A gauge must record the full tidal range, including extremes, and should be located where the sea level is unaffected by fluvial flows and other non-tidal factors. Such a gauge should be fixed to robust infrastructure, for example, a fixed pier or jetty, where it is sheltered from waves and is readily accessible to Operation and Maintenance (O&M) personnel. While not essential, accessible power and communication services would be ideal. Unfortunately, such a location does not exist in The Wash, and as a result there is no Class A gauge on the east coast between Immingham and Cromer. It will therefore be necessary to construct a bespoke platform at a suitable location where the full tidal prism can be accessed.