Open the floodgates: Designer deluges could save dammed rivers

时间:2019-03-01 05:18:01166网络整理admin

Jamey Stillings By Terri Cook BETWEEN the still waters of Lake Gruyère, held back by the Rossens dam, and the pretty town of Fribourg, the Sarine river winds lazily through western Switzerland. It’s a picture of bucolic tranquility. One day last September, though, it was anything but. Suddenly, great torrents of white water came rushing from the base of the dam. With spectators crowding vantage points and a drone capturing footage from above, it looked for all the world like a catastrophic engineering failure. In fact, it was quite the reverse. This stretch of the Sarine hadn’t run free since it was dammed for hydropower more than half a century ago, restricting its capricious flows to a predictable near-trickle. It is a story repeated around the world, with nearly half of the planet’s major river systems choked by dams. They bring important benefits, not least renewable energy, but come with a high ecological cost. Where people once marvelled at these triumphs of engineering, many have come to see dams as an environmental liability. But what if all that concrete could be part of the solution? That’s what the scientists behind the artificial flood released on the Sarine are attempting to find out. They want to unleash regular designer deluges, carefully calibrated to restore the river’s natural rhythms. The idea is to give us the best of both worlds: to keep our dams without destroying the ecosystems they exploit. The results are just beginning to dribble in,