This annual phenomenon is actually deliberately created by changing the balance of locks at Teddington and Richmond and letting the natural tide drain the Thames to enable essential maintenance of the locks, weirs and sluices and inspection of the river bed along this stretch.
The Port of London Authority issues special navigation advice during November due to the draw-off which lasts from 6th to the
27th of November this year (now extended to last until the 25th December) . Moored boats can be grounded during this time and navigation at low tide is particularly tricky.
The natural tidal shoreline near Ham – a short way downstream of Teddington Lock. Photos: Sunshine Soon
On these rare occasions to see the river bed exposed, it’s also an excellent opportunity to explore and help clean up the river (although note you may need special permission to do this).
The Environment Trust is inviting anyone interested to help collect litter on the Richmond & Twickenham foreshore whilst learning about the wildlife that inhabits the river bed via a guided tour including history of the locks. These various events will be taking place on 12th (Twickenham) and 26th November (Richmond) – see website for more info but all will require wellies!
[Update] A shot of the environment group cleaning the exposed riverbed at Eel Pie Island in Twickenham.