![The entrance to Portishead Harbour and Marina Quays off the Bristol Channel on a sunny February day. Old harbour walls and muddy entrance at low tide Stock Photo - Alamy The entrance to Portishead Harbour and Marina Quays off the Bristol Channel on a sunny February day. Old harbour walls and muddy entrance at low tide Stock Photo - Alamy](https://c8.alamy.com/comp/2AWD019/the-entrance-to-portishead-harbour-and-marina-quays-off-the-bristol-channel-on-a-sunny-february-day-old-harbour-walls-and-muddy-entrance-at-low-tide-2AWD019.jpg)
The entrance to Portishead Harbour and Marina Quays off the Bristol Channel on a sunny February day. Old harbour walls and muddy entrance at low tide Stock Photo - Alamy
![The harbour wall at the entrance to the locks on the Cardiff Bay barrage. It is a sea defence against the extremely high tides of the Bristol Channel Stock Photo - Alamy The harbour wall at the entrance to the locks on the Cardiff Bay barrage. It is a sea defence against the extremely high tides of the Bristol Channel Stock Photo - Alamy](https://c8.alamy.com/comp/MPX0C6/the-harbour-wall-at-the-entrance-to-the-locks-on-the-cardiff-bay-barrage-it-is-a-sea-defence-against-the-extremely-high-tides-of-the-bristol-channel-MPX0C6.jpg)
The harbour wall at the entrance to the locks on the Cardiff Bay barrage. It is a sea defence against the extremely high tides of the Bristol Channel Stock Photo - Alamy
![Steart Marshes adjoining the Bristol Channel and the River Parrett Estuary, allowed to flood on high tides to create new saltmarsh habitat. Hinkley Po Stock Photo - Alamy Steart Marshes adjoining the Bristol Channel and the River Parrett Estuary, allowed to flood on high tides to create new saltmarsh habitat. Hinkley Po Stock Photo - Alamy](https://c8.alamy.com/comp/2BND6AH/steart-marshes-adjoining-the-bristol-channel-and-the-river-parrett-estuary-allowed-to-flood-on-high-tides-to-create-new-saltmarsh-habitat-hinkley-po-2BND6AH.jpg)
Steart Marshes adjoining the Bristol Channel and the River Parrett Estuary, allowed to flood on high tides to create new saltmarsh habitat. Hinkley Po Stock Photo - Alamy
![Comparison of maximum spring tide currents for: (a) no scheme; (b) the... | Download Scientific Diagram Comparison of maximum spring tide currents for: (a) no scheme; (b) the... | Download Scientific Diagram](https://www.researchgate.net/profile/Roger-Falconer/publication/292019238/figure/fig6/AS:421543906942997@1477515307512/Comparison-of-maximum-spring-tide-currents-for-a-no-scheme-b-the-Severn-Barrage-and_Q320.jpg)