By Sally Westwood
Common Buzzard
Deben Estuary and changing tides
The River Deben is thought to commence west of Ulveston Hall, near Mickfield, alternatively the Deben may stem from the south in Bedingfield1. The river flows along gradually turning into an estuary between Melton and Woodbridge, and enters the North Sea at Harwich Haven, between Bawdsey and Felixstowe Ferry. A significant feature of the Deben Estuary is the changing tides. The tide is described as “the ocean’s response to the gravitational pull of the Moon and the Sun”2 but more specifically, “it is the variation in this pull over the surface of the Earth that makes tides”3. When tide is rising and coming in, the North Sea washes heavy sediment4 into the Deben which forms intertidal flats around the area of the mouth of the estuary at Felixstowe Ferry. This produces sand and shingle beaches. Finer silt is driven along the estuary into the river to form the mudflats we see at the sides of the river near Woodbridge, and more extensively further along the river at Melton, Wilford Bridge and beyond. The tide rises and falls twice a day5. High water on the River Deben occurs at intervals of approximately twelve hours, and the tide starts ebbing to low tide about six hours following high tide. High tide occurs one hour later each day. The height of the tide is affected by both the strength and direction of wind and atmospheric pressure6.