Tag Archives: groundwater

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13 March 2018, The Conversation, More of us are drinking recycled sewage water than most people realise. The world is watching as Cape Town’s water crisis approaches “Day Zero”. Questions are being asked about which other cities could be at riskand what can they do … Continue reading →

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17 February 2017, New York Times, Mexico City, Parched and Sinking, Faces a Water Crisis. Climate change is threatening to push a crowded capital toward a breaking point. MEXICO CITY — On bad days, you can smell the stench from a mile away, drifting over a nowhere sprawl of highways and office parks. When the Grand Canal was completed, at the end of the 1800s, it was Mexico City’s Brooklyn Bridge, a major feat of engineering and a symbol of civic pride: 29 miles long, with the ability to move tens of thousands of gallons of wastewater per second. It promised to solve the flooding and sewage problems that had plagued the city for centuries. Only it didn’t, pretty much from the start. The canal was based on gravity. And Mexico City, a mile and a half above sea level, was sinking, collapsing in on itself. It still is, faster and faster, and the canal is just one victim of what has become a vicious cycle. Always short of water, Mexico City keeps drilling deeper for more, weakening the ancient clay lake beds on which the Aztecs first built much of the city, causing it to crumble even further. As Arnoldo Kramer, Mexico City’s chief resilience officer, put it: “Climate change has become the biggest long-term threat to this city’s future. And that’s because it is linked to water, health, air pollution, traffic disruption from floods, housing vulnerability to landslides — which means we can’t begin to address any of the city’s real problems without facing the climate issue.” Read More here

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21 December 2016, The Conversation, Why we can get over the ‘yuck factor’ when it comes to recycled water. In light of climate change and a growing population, water authorities around the world are looking at the treatment of recycled water to achieve water security and sustainability. Recent authors on The Conversation have raised the possibility of expanding the use of water recycling in Australia, noting the potential benefits for domestic, agricultural and industrial water supply. Some contributors have noted that the major roadblocks to water recycling, in places where it could be beneficial, are not technical issues, but public reluctance to use recycled water. Emotional Responses In the past, our aversion to recycled water has been explained by the “yuck factor”. Some people have an emotional response of disgust to using recycled water, even when they know it has been highly treated and is safe. There are large individual differences in the strength and type of different people’s disgust responses. Psychologists have tried to understand why our thought processes can lead some people to think of recycled water as unclean. One explanation is contagion thinking, the idea that once water has been defiled it will always remain unclean, regardless of treatment, at least according to the mental models that underlie our emotional responses. What such approaches often neglect is that cognition does not occur in a cultural vacuum, but is affected by the associations and stigmas of society. It is important to note that these emotional responses are often in conflict with our rational thinking. Some theorists, such as Nobel laureate Daniel Kahneman, have argued that we make judgements using two contrasting systems. One of these systems is slow and operates according to a formal risk calculus. The other is fast, based on positive or negative emotional responses. Because of this, how we feel about someone or something (positively or negatively) is often as important as what they are being judged on. In other words, the fact that a person understands that a highly treated sample of recycled water is safe to drink may not be enough to stop the emotional response, as we often tend to think intuitively, drawing on our social and cultural values. The most important question, however, is whether the emotional responses some people have to recycled water can be changed. And what role do stigmas associated with cultural norms play in shaping these? Read More here

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17 November, ABC Science, New map of Earth’s groundwater to help estimate when it may run out. Less than 6 per cent of ground water in the upper two kilometres of the Earth’s landmass is renewable within a human lifetime, according to a new map showing the world’s hidden groundwater. “This has never been known before,” said the study’s lead author, Dr Tom Gleeson of the University of Victoria in Canada. “We already know that water levels in lots of aquifers are dropping. We’re using our groundwater resources too fast -faster than they’re being renewed.” Using data and computer models, an international group of hydrologists has produced the first data-driven estimate of the Earth’s total supply of groundwater. “Since we now know how much groundwater is being depleted and how much there is, we will be able to estimate how long until we run out.” The study, published in the journal Nature Geoscience, estimated a total volume of underground water to be almost 23 million cubic kilometres, of which 0.35 million cubic kilometres is younger than 50 years old. Underground water is found beneath the Earth’s surface and is recharged by rain, snow or water that leaks from the bottom of lakes and rivers. Its age can be a few months to millions of years. It can be found as deep as nine kilometres, according to the United States Geological Survey. “Since we now know how much groundwater is being depleted and how much there is, we will be able to estimate how long until we run out,” Dr Gleeson said. Read More here