Dee Estuary Bore

In most tidal rivers the change from ebb to flood is a gradual process. The ebb current downstream slows, there's a period of slack water and then very slowly the flood tide starts flowing upstream. In some rivers though, it's very different. The start of the flood tide is a noticable and vigorous wave which is known as a bore. 
Both the Dee and the Mersey do this. They're strongest during high tides i.e. above 30ft at Liverpool, which happens only a few days each year but lower tides can produce big bores during a period of dry weather reducing fresh water flow in the rivers.

Click your browsers BACK button to return to Venue Descriptions.