Flood planners should not forget beavers

MONTREAL — Busy beavers can curtail rising floodwaters, new research shows. The work suggests that beaver dams can provide natural flood protection and that officials should consider encouraging beaver construction projects as part of flood prevention plans, the researchers say.

Beavers construct dams from twigs and mud to create large, relatively calm pools of water to live in. Scientists had previously believed that beaver dams had little impact on floodwater storage during rainstorms, ecohydrologist Cherie Westbrook said May 6 at a meeting of the American Geophysical Union and other organizations.

As 19 centimeters of rain soaked Alberta, Canada, over three days in June 2013, Westbrook, of the University of Saskatchewan in Saskatoon, Canada, and colleagues monitored beaver dams along a stream. Water levels behind the dams rose 10 to 50 centimeters during the storm, postponing and reducing the peak surge of water flowing down the stream.

During the rainstorm, a 10-meter-wide breach burst open in one of the dams, causing a torrent of water to gush downstream. Surprisingly, despite the large rupture, the damaged dam still held back 15 centimeters of water as the storm progressed.