News and science on dams

They do more than hold water

Beavers have constructed dams for millions of years. The impoundments these mammals create are known to provide habitat for birds, fish, and other wetland species. Beaver ponds also diminish soil erosion and mitigate flooding.

People have constructed dams for millennia. A handful constructed by the Romans still stand today. We build dams for irrigation, drinking water supplies, and hydroelectric power. Dams help us avoid floods.

Dams can also create environmental problems; they can also become safety hazards when they get old. For these reasons people have, in the past 20 years or so, started to destroy dams and allow rivers to run free again. There have been some new developments and science concerning dams recently, so I thought I’d write about them for this week’s Green Dispatch.

Dams move the Earth

Feeling a bit off kilter? Maybe it’s because the whole world has gotten a little cattywampus. Due to all the water we have dammed in the last 190 years—redistributing billions of tons of water from the oceans to the land masses—scientists have found we have moved the North Pole by three feet.

Going back to 1835, toward the beginning of the Industrial Revolution, people went on a spree constructing dams in North America and Europe. After 1954, the big surge in dam construction shifted to Africa and Asia.

Researchers at Harvard looked at 7,000 major dams and calculated the amount of water held by their reservoirs and lakes and found this worldwide impoundment to be responsible for the shift in the North pole. They published their findings in the journal Geophysical Research Letters in May. They explain that the entire globe has not moved; rather, the lithosphere, the outermost rocky layer, has shifted.