River Mouths See Increased Tidal Range

Joris Beemster of Wageningen University researched centuries-old archives and found that the difference between high and low tide has grown in many river mouths. Beemster, who grew up in the Dutch village of Griete beside the Westerschelde estuary, began noticing the changing tides as a child. His recent study in Nature Geoscience shows that human interventions—like building dikes, polders, and dredging shipping lanes—have had a greater impact on rising water levels than climate change itself.

These rising tides harm plants and animals, and could pose risks to people, drawing a parallel to the 1953 Dutch flood disaster which occurred after decades of dike construction. Though Dutch dikes now withstand storms expected only once in ten thousand years, even small margins can quickly become dangerous, as seen with “high tide flooding” in the United States.

Beemster’s research also examines 17th-century maps, revealing how landscapes have changed and how modern alterations to riverbeds and channels amplify tidal effects. While restoring natural landscapes could help, solutions are complicated by economic factors like maintaining deep shipping lanes for ports like Antwerp. The work continues as Beemster plans to center future research on former colonies and the impact of human interventions there.