Which cities are at greatest risk from sea level rise? Satellite measurements give us the general picture of where waters are rising fastest, but they can’t capture the local detail. Now a study reveals that the way the Earth rotates causes river outflow water to pile up more in some locations than others.
Chris Piecuch, from the Woods Hole Oceanographic Institution, and colleagues gathered decades worth of river level and tidal gauge data from eastern US locations, along with measurements of water density, salinity and the Earth’s rotation. Their results, published in PNAS, show that, due to the combined effects of Earth’s rotation and fresh river water being less dense than salty ocean water, in the northern hemisphere the river discharge flows to the right-hand side out of the river, and in the southern hemisphere to the left-hand side. This effect raises sea level more in one direction along the coast than the other.
“For example, our findings suggest that coastal communities to the west of the Mississippi river mouth – along the coasts of Louisiana and Texas – will be most influenced by outflow from that particular river,” said Piecuch. In low-lying areas this could help to identify which communities might be most at risk when a big storm sweeps through.
