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The trouble with dams
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The trouble with dams A UK town has been evacuated after damage to a dam risked disaster. The likelihood of such events may be rising, reports Michael Le Page DAMS are typically built to cope with once in a century floods. But global warming is raising the odds of extreme events and therefore the chances of dams failing too. “The 1-in-100-year event is perhaps happening every five years,” says Roderick Smith at Imperial College London. “I’m absolutely convinced that it is due to climate change.” On 1 August, 1500 people from the UK town of Whaley Bridge were asked to evacuate after damage to a dam built in 1831 (pictured). Problems began when a section of the spillway slope where water drains out of the reservoir was damaged after heavy rain. The immediate danger has passed as the reservoir behind the dam has
been partly emptied into rivers by using pipes and pumps. The Whaley Bridge incident is similar to that at the Oroville dam in California in February 2017. Both are earthen dams where excess water flows over the top of the dam and down a concretelined spillway. If this concrete is damaged, the water flowing down the spillway can rapidly erode the earth underneath, leading to the entire dam wall collapsing There is a much greater chance of this happening when extreme rainfall or snow melt leads to very high water flows into already full reservoirs. A 2018 study concluded that climate change exacerbated the high water flows that led to the
erosion of the Oroville dam spillway, which resulted in the evacuation of 190,000 people and repairs costing $1.1 billion. The role that climate change may have played at Whaley Bridge isn’t yet clear. There haven’t been any serious dam collapses in the UK since the Eigiau and Coedty dams failed in 1925, killing 16 people. After that, regular inspections by qualified engineers became mandatory. Globally there have been at least 40 dam failures since 2000. The most recent was the Tiware dam breach in India on 2 July after heavy rain. At least 19 people died. The worst disaster was in 1975, when around 170,000 died after China’s Banqiao dam gave way. ❚
BRAZIL’S president Jair Bolsonaro has fired the director of the nation’s space agency INPE. Ricardo Galvao was sacked after he and his colleagues revealed that deforestation in the Amazon has increased since Bolsonaro took power in January. More than 3700 square kilometres of forest have been cut down so far this year, according to INPE, a figure which is backed up by other countries monitoring the region. But Bolsonaro claimed that the INPE numbers were a “lie” and were released to harm Brazil’s reputation. ❚ Michael Le Page
Chemistry
Metal tongue has a taste for whisky AN ARTIFICIAL tongue may one day help tackle the counterfeit alcohol trade. Alasdair Clark at the University of Glasgow, UK, and his colleagues built the device using two different types of metal taste buds. To use it, they pour whisky over the metals and measure how light is absorbed (Nanoscale, doi.org/c85z). This allowed them to tell apart samples of the same brand of whisky aged in different barrels with more than 99 per cent accuracy. The tongue could also differentiate whisky samples that had been aged for 12, 15 or 18 years. ❚ Staff and agency 10 August 2019 | New Scientist | 5
Shrinking wasps Some insects may be getting smaller due to climate change p8
Terrascope We could use Earth as a lens for a giant space telescope p10
Prenatal vitamins Folic acid may be important for both sexes p14
Hypervelocity star Alien sun spotted speeding its way out of our galaxy p15
Deforestation
LEON NEAL/GETTY IMAGES
Bolsonaro hits out over Amazon data
The trouble with dams A UK town has been evacuated after damage to a dam risked disaster. The likelihood of such events may be rising, reports Michael Le Page DAMS are typically built to cope with once in a century floods. But global warming is raising the odds of extreme events and therefore the chances of dams failing too. “The 1-in-100-year event is perhaps happening every five years,” says Roderick Smith at Imperial College London. “I’m absolutely convinced that it is due to climate change.” On 1 August, 1500 people from the UK town of Whaley Bridge were asked to evacuate after damage to a dam built in 1831 (pictured). Problems began when a section of the spillway slope where water drains out of the reservoir was damaged after heavy rain. The immediate danger has passed as the reservoir behind the dam has
been partly emptied into rivers by using pipes and pumps. The Whaley Bridge incident is similar to that at the Oroville dam in California in February 2017. Both are earthen dams where excess water flows over the top of the dam and down a concretelined spillway. If this concrete is damaged, the water flowing down the spillway can rapidly erode the earth underneath, leading to the entire dam wall collapsing There is a much greater chance of this happening when extreme rainfall or snow melt leads to very high water flows into already full reservoirs. A 2018 study concluded that climate change exacerbated the high water flows that led to the
erosion of the Oroville dam spillway, which resulted in the evacuation of 190,000 people and repairs costing $1.1 billion. The role that climate change may have played at Whaley Bridge isn’t yet clear. There haven’t been any serious dam collapses in the UK since the Eigiau and Coedty dams failed in 1925, killing 16 people. After that, regular inspections by qualified engineers became mandatory. Globally there have been at least 40 dam failures since 2000. The most recent was the Tiware dam breach in India on 2 July after heavy rain. At least 19 people died. The worst disaster was in 1975, when around 170,000 died after China’s Banqiao dam gave way. ❚
BRAZIL’S president Jair Bolsonaro has fired the director of the nation’s space agency INPE. Ricardo Galvao was sacked after he and his colleagues revealed that deforestation in the Amazon has increased since Bolsonaro took power in January. More than 3700 square kilometres of forest have been cut down so far this year, according to INPE, a figure which is backed up by other countries monitoring the region. But Bolsonaro claimed that the INPE numbers were a “lie” and were released to harm Brazil’s reputation. ❚ Michael Le Page
Chemistry
Metal tongue has a taste for whisky AN ARTIFICIAL tongue may one day help tackle the counterfeit alcohol trade. Alasdair Clark at the University of Glasgow, UK, and his colleagues built the device using two different types of metal taste buds. To use it, they pour whisky over the metals and measure how light is absorbed (Nanoscale, doi.org/c85z). This allowed them to tell apart samples of the same brand of whisky aged in different barrels with more than 99 per cent accuracy. The tongue could also differentiate whisky samples that had been aged for 12, 15 or 18 years. ❚ Staff and agency 10 August 2019 | New Scientist | 5