It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, August 24, 2021
WATER IS LIFE
New research in rural Costa Rica suggests community-based monitoring can improve water management
New research published in the Proceedings of the National Academy of Sciences (PNAS) suggests that externally-encouraged, community-based monitoring can improve the management of shared resources. Researchers from the University of Maryland, Baltimore County (UMBC); Wageningen University & Research in the Netherlands; and Johns Hopkins University sought to determine if a community-based monitoring approach promoted by an outside organization could help local communities in rural Costa Rica improve water management. Although replications are needed, the results are encouraging -- promising news ahead of World Water Week 2021.
Citizen engagement program
“Community-based monitoring to facilitate water management by local institutions in Costa Rica” examines a monitoring program aimed to reduce groundwater extraction from aquifers. The program also sought to improve the quality of water accessed by participating Costa Rican communities and their satisfaction with the water supply.
“This study allows us to directly see how community-based monitoring can support more desirable water management outcomes and to analyze the ways to attain those outcomes,” said co-author Maria Bernedo Del Carpio, assistant professor at UMBC. “Monitoring a natural resource or an institution can generate valuable information that will improve governance, but it is necessary to engage decision-makers and the community.”
The process included increased communication about field conditions, additional scrutiny of user and management authority activities, and fostering citizen engagement in water management. Using a specially designed smartphone application and WhatsApp, monitors reported weekly on the conditions of the water system, including service disruptions, water quality, leaks, and source contamination. The app automatically compiled the individual reports into a summary report, which was then made available to the community water management committees and water users.
Improvements in water quality
The program was randomly implemented in 80 of 161 rural Costa Rican communities that expressed an interest in participating. One year after the program started, the team detected that it had modest effects in the predicted directions: less groundwater extracted, better water quality, and more satisfied users. Although the estimated effects are imprecise, the monitoring program appears to be equally or more cost-effective for reducing groundwater extraction in comparison with another program in the same region that encouraged households to adopt water-efficient technologies.
“Understanding how we can make institutions and governance more effective is essential for successfully addressing the most important policy challenges of the 21st century,” said co-author Paul Ferraro a Bloomberg Distinguished Professor at Johns Hopkins University. “We believe this study is an exemplar of how such an understanding can be more effectively generated by careful field testing using the very best scientific practices.”
The Antarctic Ice Sheet, Earth’s southern polar ice sheet, has grown and receded and grown again over millions of years. This changing mass influences the planet’s climate and sea levels, with historic data recorded in sediment, meltwater and surrounding oceans. However, the remote and difficult nature of the sheet leaves researchers with limited access to collect samples and data that may reveal missing pieces in the ebb and flow of historic climate changes.
The results were published on June 14 in Geology.
“An accurate reconstruction of Antarctic Ice Sheet changes is required to develop a further understanding of ice-sheet response to climate changes,” said paper author Takeshige Ishiwa, postdoctoral researcher at the National Institute of Polar Research, Research Organization of Information and Systems.
According to Ishiwa, ice sheet changes before the Last Glacial Maximum about 20,000 years ago, when the ice sheets across the globe were their most extensive, have not been well documented. With limited records, there are inconsistencies in modeled data and geological observations. For example, despite a global sea level drop of more than 40 meters before the Last Glacial Maximum, sedimentary samples from two bays in East Antarctica indicate sea levels did not differ much from modern measurements.
To better understand this inconsistency, the researchers modeled how land under the ice sheet moves, called glacial isostatic adjustment. Even when ice melts, the land has long-lasting effects and moves differently as a result. The researchers simulated various scenarios and found that only one appeared to explain the sea level discrepancy.
“Our glacial isostatic adjustment modeling results reveal that the Indian Ocean sector of Antarctic Ice Sheet would have been required to experience excess ice loads before the Last Glacial Maximum in order to explain limited geological data,” Ishiwa said. “We suggest that the Antarctic Ice Sheet partly reached its maximum thickness before the Last Glacier Maximum.”
The thicker ice appears to have depressed the continent, Ishiwa said, changing the gravitation field of the land and sea to generate the high sea levels.
“Geological evidence supports our glacial isostatic adjustment-based Antarctic Ice Sheet reconstruction before the Last Glacial Maximum,” Ishiwa said, noting how sediment and meltwater data indicates that the ice sheet had partially decayed before the Last Glacial Maximum.
The researchers plan to conduct another field survey and obtain additional geological data to better understand changes in the Antarctic Ice Sheet.
Co-authors include Jun’ichi Okuno and Yusuke Suganuma, both with the National Institute of Polar Research and the Department of Polar Research Science, School of Multidisciplinary Science, The Graduate University for Advanced Studies (SOKENDAI).
The Japan Society for the Promotion of Science, the TOREY Science Foundation and the Giant Reservoirs-Antarctic program supported this work.
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About National Institute of Polar Research (NIPR)
The NIPR engages in comprehensive research via observation stations in Arctic and Antarctica. As a member of the Research Organization of Information and Systems (ROIS), the NIPR provides researchers throughout Japan with infrastructure support for Arctic and Antarctic observations, plans and implements Japan's Antarctic observation projects, and conducts Arctic researches of various scientific fields such as the atmosphere, ice sheets, the ecosystem, the upper atmosphere, the aurora and the Earth's magnetic field. In addition to the research projects, the NIPR also organizes the Japanese Antarctic Research Expedition and manages samples and data obtained during such expeditions and projects. As a core institution in researches of the polar regions, the NIPR also offers graduate students with a global perspective on originality through its doctoral program. For more information about the NIPR, please visit:https://www.nipr.ac.jp/english/
About the Research Organization of Information and Systems (ROIS)
The Research Organization of Information and Systems (ROIS) is a parent organization of four national institutes (National Institute of Polar Research, National Institute of Informatics, the Institute of Statistical Mathematics and National Institute of Genetics) and the Joint Support-Center for Data Science Research. It is ROIS's mission to promote integrated, cutting-edge research that goes beyond the barriers of these institutions, in addition to facilitating their research activities, as members of inter-university research institutes.
A study that monitored surface waters in the wake of 2018’s Hurricane Florence finds that waters contaminated by fecal bacteria were affected by both human and swine waste.
“We found that surface waters in eastern North Carolina were more likely to face dual contamination than to be contaminated by either human waste or swine waste by themselves,” says Angela Harris, corresponding author of the study and an assistant professor of civil, construction and environmental engineering at North Carolina State University.
“This means people are dealing with multiple hazards,” Harris says. “It also means there are two sources of fecal contamination that need to be addressed. It’s not just the swine industry, and it’s not just wastewater treatment plants or septic systems.”
For the study, researchers collected surface water samples at 40 sites across eastern N.C. Samples were collected one week after Hurricane Florence made landfall in September 2018, and again one month after landfall. These samples are referred to as Phase 1 and Phase 2, respectively.
The researchers tested the water samples for a variety of bacteria. Specifically, the samples were tested for: E. coli – an indicator species used to identify fecal contamination and the likelihood that there are pathogens present; pathogens such as Arcobacter butzleri and various Listeria species; and bacterial species associated specifically with either swine or humans, so that researchers could trace contamination back to its source.
“About 30% of the surface water sites we tested had levels of bacteria that would have made those waters unsafe for swimming,” Harris said.
The most commonly found pathogen was Arcobacter, a finding the research team published late last year. The new study reports that the presence of Arcobacter wasn’t associated with human or swine fecal markers. In other words, it’s not clear where the pathogen is coming from.
Another mystery was that the levels of E. coli in Phase 2 samples taken from permanent water channels (as opposed to floodplains) were actually higher than the levels of E. coli in the Phase 1 samples.
“We’re not sure why E. coli levels jumped in those Phase 2 samples,” Harris says. “It could be because water levels were decreasing, so there was less dilution. It could be due to temporary changes in regulatory requirements in the wake of the hurricane. It could be some other variable we haven’t identified. We need a lot more monitoring data to begin to tease that apart.
“A lot of post-flooding work has been done in urban areas,” Harris says. “This is one of the few studies that looks at post-flooding water quality impacts in rural, agricultural areas. And our findings suggest that this merits a much closer look. This work highlights the need for more routine water quality monitoring in these areas that tests for the bacteria we were looking at here. That could help us establish broader baseline measures for water quality.
“This is particularly important given concerns around antibiotic-resistant pathogens and the likelihood that we’ll be seeing more extreme wet weather events in the future.”
The study, “Microbial Contamination in Environmental Waters of Rural and Agriculturally-Dominated Landscapes Following Hurricane Florence,” is published in the journal ACS ES&T Water. The paper was co-authored by Emine Fidan, a Ph.D. student at NC State; Natalie Nelson and Mahmoud Sharara, assistant professors of biological and agricultural engineering at NC State; Ryan Emanuel, a professor of environmental resources at NC State; Theo Jass and Jeffrey Niedermeyer, former research assistants at NC State; Sophia Kathariou, professor of food, bioprocessing and nutrition sciences at NC State; Francis de los Reyes III, professor of civil, construction and environmental engineering at NC State; and Diego A. Riveros-Iregui and Jill R. Stewart of the University of North Carolina at Chapel Hill.
The study was done with support from the National Science Foundation, under grants 1901588 and 1901202; the North Carolina Policy Collaboratory; and the International Life Sciences Institute.
The “megadrought” impacting the Colorado River system this year has been devastating to the 40 million people who rely on it for water. But could this drought have been predicted? Will we be able to predict the next one?
Mountain watersheds provide 60 to 90% of water resources worldwide, but there is still much that scientists don’t know about the physical processes and interactions that affect hydrology in these ecosystems. And thus, the best Earth system computer models struggle to predict the timing and availability of water resources emanating from mountains.
Now a team of U.S. Department of Energy scientists led by Lawrence Berkeley National Laboratory (Berkeley Lab) aims to plug that gap, with an ambitious campaign to collect a vast array of measurements that will allow scientists to better understand the future of water in the West. The Surface Atmosphere Integrated Field Laboratory (SAIL) campaign will start on September 1, when scientists flip the switch on a slew of machinery that has been amassed in the Upper Colorado River Basin.
Over the course of two falls, two winters, two springs, and a summer, more than three dozen scientific instruments – including a variety of radars, lidars, cameras, balloons, and other state-of-the-art equipment – will collect a treasure trove of data on precipitation, wind, clouds, aerosols, solar and thermal energy, temperature, humidity, ozone, and more. That data can then be used to turbocharge the capabilities of Earth system models and answer many scientific questions about how, why, where, and when rain and snow will fall. In close collaboration with researchers specializing in Earth’s surface and subsurface, the SAIL campaign will help the scientific community understand how mountains extract moisture from the atmosphere and then process the water all the way down to the bedrock beneath Earth’s surface. Ultimately, this will provide the tools for scientists to better predict the future availability of water.
“The Upper Colorado River powers more than $1 trillion in economic activity and provides an immense amount of hydroelectric power, but it’s very understudied compared to how important it is,” said Berkeley Lab scientist Daniel Feldman, the lead SAIL investigator. “We’re starting to see really dramatic consequences from the changing water resources, but the details of what is actually going on in these places where the water's coming from – those details matter, and that’s what SAIL is focused on.”
CAPTION
This rain gauge will measure the amount of liquid precipitation that falls during ARM’s Surface Atmosphere Integrated Field Laboratory (SAIL) field campaign in Gothic, Colorado. The measurements from the rain gauge will also help scientists validate precipitation estimates from radar. The SAIL campaign, which will run from September 2021 to June 2023, will help scientists better understand how water is produced and transported in mountainous watersheds.
CREDIT
John Bilberry, Los Alamos National Laboratory
From the Arctic to the Rockies
SAIL is a research campaign managed by DOE’s Atmospheric Radiation Measurement (ARM) user facility, a key contributor to climate research with its stationary and mobile climate observatories located throughout the United States and around the world. Much of the equipment being used in SAIL has just returned from a one-year Arctic expedition.
“SAIL is a timely campaign because of the ongoing drought in the Western United States,” said Sally McFarlane, DOE Program Manager for the ARM user facility. “The Colorado River is of particular concern because it supplies water to 40 million people. SAIL is bringing together data from ARM and other research programs from within DOE to ultimately help provide insights into the atmospheric processes and land-atmosphere interactions that impact rain and snow in the upper Colorado River watershed.”
SAIL is truly a broad, collaborative effort. ARM is co-managed by nine DOE national labs; Los Alamos National Lab leads the overall management and operations of the ARM mobile observatory while scientists from several other DOE labs, including Argonne, Brookhaven, Pacific Northwest, and Oak Ridge National Labs, work closely with Los Alamos and Berkeley Lab to support SAIL science and operations. A number of university researchers from Colorado State University, UC Berkeley, UC Irvine, UC Davis, Oregon State University, Indiana University, Pennsylvania State University, University of Utah, Desert Research Institute, and Boise State University are also involved in the research.
The instruments are mostly housed in large containers sited in the picturesque mountain town of Gothic, Colorado, an old mining town near Crested Butte, Colorado. The facility is hosted by the Rocky Mountain Biological Laboratory, which is dedicated to research on high-altitude ecosystems. A staff of three technicians will monitor the instruments around the clock.
“This is a profound and incredibly unique opportunity and represents a first-of-its-kind experiment in mountainous systems worldwide, bridging the processes from the atmosphere all the way down to bedrock,” said Berkeley Lab scientist Ken Williams, the lead on-site researcher for SAIL.
CAPTION
On July 1, 2021, Heath Powers, site manager for the second ARM Mobile Facility, helps set up radiometers for ARM’s Surface Atmosphere Integrated Field Laboratory (SAIL) field campaign in Gothic, Colorado. To his right is site technician Wessley King. The SAIL campaign, which will run from September 2021 to June 2023, will provide insights into mountainous water-cycle processes. Data from the radiometers will be used to help determine the site’s surface energy balance.
CREDIT
David Chu, Los Alamos National Laboratory
SAIL science: better models to answer tough questions
Having this volume of data at a wide range of spatial and temporal scales will allow scientists to begin to understand the physical processes that may affect mountain hydrology and answer questions such as how dust, wildfire, hot drought, tree mortality, and other phenomena might affect the watershed. Ultimately, the data will be fed into Earth system models so they can “get the water balance right.”
“Our models that predict what future water is going to be – their resolution is now about 100 kilometers [62 miles], but there's a lot of activity that happens in 100 kilometers, a lot of terrain variability, a lot of differences in precipitation, and surface and subsurface processes,” Feldman said. “So really the question is, what are all the details that need to go into those big models, so that we can get them to get the water balance right? And that's why this is really exciting – we’ll be measuring the inputs and the outputs at a fundamental level to develop a benchmark dataset for the scientific community to evaluate and improve their models.”
DOE’s Atmospheric System Research (ASR) program works closely with ARM to improve understanding of the key processes that affect the Earth’s radiative balance and hydrological cycle.
“ASR research projects during the SAIL campaign will help us learn more about the cloud, aerosol, precipitation, and radiation processes that affect the water cycle in the upper Colorado River watershed,” said Jeff Stehr, a DOE Program Manager for ASR. “Ultimately, this work will help us improve climate models so that they can be used to better understand, predict, and plan for threats to water resources in the arid West and globally.”
SAIL leverages the substantial efforts that Berkeley Lab has already undertaken in this area: it has been leading field studies at the East River watershed of the Colorado Upper Gunnison Basin since 2014, as part of the DOE-funded Watershed Function Scientific Focus Area project. SAIL will build on that research effort, bringing together a wide range of scientific disciplines to create the world’s first bedrock-to-atmosphere mountain integrated field laboratory.
“To have hydrologists working with precipitation process scientists, aerosol researchers working with snow process researchers, that's a really important part here, and it's unique and exciting,” Feldman said.
Some of the practical questions the SAIL campaign could help answer include:
How do we plan for a future of low snow or snowfall changing to rainfall? “Our planning for the Colorado River is largely based on historical weather patterns that might be changing, from snow to rain,” Feldman said.
How do activities and disturbances in the forest affect water quality and water availability? “It’s not just about the total volume of water exiting these systems,” Williams said. “We’ll also be looking at how land activities – such as wildfire and forest management – affect the concentrations of constituents in the water and overall water quality.”
Will dams overflow? The U.S. Bureau of Reclamation, the federal agency charged with managing dams in the western U.S., will be using the new data coming in from the radar system to help with controlled dam and reservoir operations. Feldman noted: “There have been some pretty scary situations that have arisen when rain falls on snow. The Oroville Dam disaster [in California in 2017] is just one of many such examples.”
Additionally, one of the weather radars will be located at a ski area owned by Vail Resorts, a major Colorado ski resort, which could benefit outdoor enthusiasts as well as scientists. And the research will also be useful to organizations such as water utilities and the Bureau of Reclamation that are experimenting with weather modification technologies, such as cloud-seeding.
Other federal agencies join the bandwagon
All the data collected by SAIL will be freely available to researchers. What’s more, a bevy of researchers from other federal agencies are undertaking field campaigns in the area with complementary research efforts.
The National Oceanic and Atmospheric Administration (NOAA), a Department of Commerce agency, has launched a project called SPLASH, or the Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology, to improve weather and water prediction in the Colorado mountains and beyond. It will also be making detailed atmospheric co-observations in the SAIL study area.
The U.S. Geological Survey (USGS), a Department of Interior agency, has developed an Upper Colorado Next Generation Water Observing System (NGWOS) to provide real-time data on water quantity and quality in more affordable and rapid ways than previously possible, and in more locations.
“It’s quite rare for a single research question, the future of water in the West, to integrate the research activities of investigators across multiple federal agencies,” Williams noted.
But the scale of the challenge, and the prospect of a low- to no-snow future, calls for nothing less than an all-hands-on-deck response by scientists. “We need to understand the range of risks that we’re facing moving forward,” Feldman said. “The term ‘no-analog future’ is a really big one for us.”
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Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams,Lawrence Berkeley National Laboratory and its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visitenergy.gov/science.
IMAGE: THIS ILLUSTRATION SHOWS A PALEOARTIST'S RECONSTRUCTION OF THE THREE EXTINCT RHINOCEROS SPECIES WHOSE GENOMES WERE SEQUENCED AS PART OF THE STUDY. IN THE FOREGROUND IS A SIBERIAN UNICORN (ELASMOTHERIUM SIBIRICUM), AND CLOSE BEHIND ARE TWO MERCK’S RHINOCEROSES (STEPHANORHINUS KIRCHBERGENSIS). IN THE FAR BACKGROUND IS A WOOLLY RHINOCEROS (COELODONTA ANTIQUITATIS).view more
CREDIT: BETH ZAIKEN
There’s been an age-old question going back to Darwin’s time about the relationships among the world’s five living rhinoceros species. One reason answers have been hard to come by is that most rhinos went extinct before the Pleistocene. Now, researchers reporting in the journal Cell on August 24 have helped to fill the gaps in the rhino evolutionary family tree by analyzing genomes of all five living species together with the genomes of three ancient and extinct species.
The findings show that the oldest split separated African and Eurasian lineages about 16 million year ago. They also find that—while dwindling populations of rhinos today have lower genetic diversity and more inbreeding than they did in the past—rhinoceroses have historically had low levels of genetic diversity.
“All eight species generally displayed either a continual but slow decrease in population size over the last 2 million years, or continuously small population sizes over extended time periods,” said Mick Westbury (@Mick2474) of the University of Copenhagen, Denmark. “Continuously low population sizes may indicate that rhinoceroses in general are adapted to low levels of diversity.”
This notion is consistent with an apparent lack of accumulated deleterious mutations in rhinos in recent decades. Westbury says that rhinos may have purged deleterious mutations in the last 100 years, allowing them to remain relatively healthy, despite low genetic diversity.
There were some challenges to overcome, says Shanlin Liu, China Agricultural University, Beijing. “When we decided to put together all the rhinoceroses’ data and conduct a comparative genomics study, we also confronted the ‘big data’ problem,” Liu explained.
The genome data represented different data types, in part due to the inclusion of both modern and ancient DNA. The team had to develop new analysis tools to take those differences into account. The new approaches and tools they developed can now be applied to studies in other taxonomic groups.
“However, we also find that present-day rhinos have lower genetic diversity, and higher levels of inbreeding, compared to our historical and prehistoric rhinoceros genomes,” he says. “This suggests that recent population declines caused by hunting and habitat destruction have had an impact on the genomes. This is not good, since low genetic diversity and high inbreeding may increase the risk of extinction in the present-day species.”
The findings do have some practical implications for rhino conservation, the re-searchers say.
“Now we know that the low diversity we see in contemporary individuals may not be indicative of an inability to recover, but instead a natural state of rhinoceros," Westbury says. “We can better guide recovery programs to focus on increasing population size rather than individual genetic diversity.”
“We hope that this will provide a framework to better understand where translocated populations may have arisen from, direct changes in genetic diversity, and whether any populations may have been lost forever because of humans,” Westbury said.
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The researchers received support from the European Research Council, the Independent Research Fund Denmark, the Australian Research Council, the Agencia Estatal de Investigación, the Howard Hughes Medical Institute, GENCAT, the Swedish Research Council, and Formas.
Cell (@CellCellPress), the flagship journal of Cell Press, is a bimonthly journal that publishes findings of unusual significance in any area of experimental biology, including but not limited to cell biology, molecular biology, neuroscience, immunology, virology and microbiology, cancer, human genetics, systems biology, signaling, and disease mechanisms and therapeutics. Visit: http://www.cell.com/cell. To receive Cell Press media alerts, contact press@cell.com.
IMAGE: EVERY YEAR, MORE THAN 1,000 TONS OF PLASTIC RAIN DOWN ONTO NATIONAL PARKS AND WILDERNESS AREAS IN THE WESTERN U.S. IN THIS WEEK’S EPISODE, WE TALK ABOUT WHERE THAT PLASTIC COMES FROM, AND WE LOOK FOR IT IN RAIN THAT FALLS ON WASHINGTON, D.C.: HTTPS://YOUTU.BE/HUAAURZKI6U.view more
CREDIT: THE AMERICAN CHEMICAL SOCIETY
WASHINGTON, Aug. 24, 2021 — Every year, more than 1,000 tons of plastic rain down onto national parks and wilderness areas in the western U.S. In this week’s episode, we talk about where that plastic comes from, and we look for it in rain that falls on Washington, D.C.: https://youtu.be/HUAaurZKi6U.
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The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.
IMAGE: WIND TURBINE RESPONSE TO WIND AND EARTHQUAKES.view more
CREDIT: XILULI DU
WASHINGTON, August 24, 2021 -- As China's economic development continues, energy demand is rising along with it. Meeting this energy demand via fossil fuels is becoming increasingly undesirable, because it poses environmental and climate risks.
One solution is to embrace renewable energy sources, such as wind power, and it has experienced fast growth within China during the past decade. But many wind farms are being built within regions of high seismic activity.
In Journal of Renewable and Sustainable Energy, by AIP Publishing, researchers from Changzhou University and Beijing University of Technology present their work exploring the dynamic behaviors of wind turbines subjected to combined wind-earthquake loading.
The group discovered that changes in the wind increase and decrease the response amplitude of the wind turbine under weak and strong earthquakes, respectively.
"The input angle of earthquakes influences the seismic response of wind turbines, because of the asymmetry of aerodynamic damping and blade stiffness," said Xiuli Du, a co-author from Beijing University of Technology. "The wind and earthquake ground motion both induce the vibration of wind turbines, especially the blades, which changes the aerodynamic load acting on the blades."
Modern large-scale wind turbines use variable speed and variable pitch control technology, which means their dynamic behavior is affected by the controller.
"Consequently, the dynamic response of wind turbines under wind-earthquake excitation shows the coupling effect of aeroservoelasticity -- the interactions between the inertial, elastic, and aerodynamic forces that occur when an elastic body is subjected to a fluid flow," said Du. "Wind and ground motion are also random vector fields, with complex time-domain and spatial uncertainties involved when combined."
Surprisingly, the researchers found the wind simultaneously exerts a dynamic loading and damping effect on the seismic response of wind turbines. So, they caution that considering only one of these two effects could lead to inaccurate or even erroneous conclusions.
"Our work can guide the determination of wind-earthquake combinations for the seismic design of wind turbines and directly help design wind turbine structures," said Du.
Wind turbine support towers located within seismically active areas of China do not typically include redundant supports, so if one fails, it may result in a collapse of the turbines.
"While converting wind energy into electricity, wind turbines are in the operational state for most of their service life, which makes it important to study the dynamic behavior of wind turbines under wind-earthquake loading," said Du.
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The article "Dynamic behaviors of wind turbines under wind and earthquake excitations" is authored by Renquang Xi, Piguang Wang, Xiuli Du, and Chengshun Xu. It will appear in Journal of Renewable and Sustainable Energy on Aug. 24, 2021 (DOI: 10.1063/5.0054746). After that date, it can be accessed at https://aip.scitation.org/doi/10.1063/5.0054746.
ABOUT THE JOURNAL
Journal of Renewable and Sustainable Energy is an interdisciplinary journal that publishes across all areas of renewable and sustainable energy relevant to the physical science and engineering communities. Topics covered include solar, wind, biofuels and more, as well as renewable energy integration, energy meteorology and climatology, and renewable resourcing and forecasting. See https://aip.scitation.org/journal/rse.
