Combating Rising Seas, Sinking Cities

Engineering Inc. magazine

As Land Subsidence and Climate Change Threaten Infrastructure, Engineers are Pioneering Solutions for a  Sustainable Future

In 1977, a photo was taken of hydrologist Dr. Joseph F. Poland standing next to a utility pole in California’s San Joaquin Valley. Signs on the pole indicate where the ground level was in a given year: At the top, one reads 1925; further down, 1955; at his feet, 1977. The ground had sunk almost 30 feet in about 50 years as a result of groundwater pumping. One would think the image would have become a wake-up call to the dangers of land subsidence. It was not.

A recent study in Nature Communica­tions found that cities along the U.S. East Coast—home to roughly 118 million people—are sinking at a rate of roughly 0.12 inches a year. Across the nation, more than 17,000 square miles in 45 states are sinking. The situation is even worse in some places around the globe.

Mexico City, home to 21 million people, has sunk more than 32 feet in the last 60 years. Areas of Jakarta, Indonesia, population 11.2 million, have sunk 8.2 feet in the last 10 years and continue to sink almost 6 inches per year—a dilemma that has ultimately forced the Indonesian government’s decision to build a new capital city more than 1,200 miles away.

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