Autumn Spring Tides

At the end of September, the moon is full and because it is also the equinox, the tides are some of the highest of the year. The ‘Spring tide’ on the Swale fills the estuary and appears to almost drown the land. If the sea level rises as predicted then the coastal grazing marshes and reedbeds will be soon be permanently inundated. Today in the sunshine and a brisk westerly, the waters don’t break over the sea walls, just submerge nearly all of the upper saltmarsh. At high water, an assortment of boats move on the Swale and the Oare and the estuary birds shelter in large flocks at traditional high tide roosts such as on the East Flood at Oare Marshes and the tip of Shellness.

It needs a ‘storm surge’ caused by a rare combination of low atmospheric pressure and high winds from a storm to lift and push the water’s higher sometimes by one or two metres. The most infamous was the nearly three metre surge that ran down the North Sea and drowned the east coast of England on the last day of January 1953. The result was the death of more than 300 people mainly in East Anglia; the Netherlands lost over 1,800. The devastation brought about great improvements in flood warning communications because, whilst the surge was correctly predicted, none of the coastal communities received any warning. The 1958 opera Noye’s Fludde by Benjamin Britten was probably influenced by the event; he lived on the low lying coast of shingle and gorse at Aldeburgh for most of his life.

The pattern of the tide creates an unceasing cycle of feeding and enforced resting and roosting; for the waders it often appears a race to claim the best feeding spots as the high tide ebbs and exposes the first section of mud replete with molluscs and worms. Each wader species has a bill adapted to forage for different-sized prey that live at different depths; for the swans and ducks it is the algae and eelgrass on the surface that is grazed. At low tide on a still evening the typical assemblage of mute swan, teal and redshank feed and preen in the shallows on a small inlet off the Medway Estuary. The rigours of winter, especially periods with freezing temperatures, will soon demand less loafing and more time feeding to maintain condition.

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