[Rockhounds] How humans are altering the tides of the oceans

[Kreigh Tomaszewski]

It was the muddy water that caught Stefan Talke’s eye. In the mid-2000s
Talke was a postdoctoral scholar at Utrecht University, studying the river
Ems that empties into the North Sea between Germany and the Netherlands.
Decades earlier, engineers had begun dredging parts of the Ems so that
newly built ships could navigate it from a shipyard upriver.

But those changes also changed the rhythm with which tides ebbed and flowed
into the river from the sea. Those shifting tides stirred up sediment from
the river bottom and muddied its waters. Over the last 120 years the tidal
range – the distance between high and low tide – has quintupled in the Ems
estuary.

“I had always assumed tides were constant,” says Talke, now an
oceanographer at California Polytechnic State University in San Luis
Obispo. “That’s why we have tide tables.” He was amazed to discover, he
says, that not only could tides undergo long-term changes, but that they
could change by so much.

https://www.bbc.com/future/article/20200703-how-humans-are-altering-the-tides-of-the-oceans