Dust Control at the Oceano Dunes

Dust Control at the Oceano Dunes

Last May, DRI scientist Jack Gillies, Ph.D. spent three weeks at the Oceano Dunes State Vehicular Recreation Area (SVRA), a 3,500-acre area of sandy beach and coastal dune habitat located within the Guadalupe-Nipomo Dunes complex on the central California coast. Unlike most visitors to this popular park, Gillies was not there to camp, or to ride OHVs over the miles and miles of beaches and dunes; he was there to measure the dust.

For more than 100 years, people have visited the Oceano Dunes region to drive on the beaches – beginning in the early 1900s with horse-drawn carriages and early automobiles, then later with ATVs, dune buggies, dirt bikes, trucks, RVs, and other types of vehicles. All of this activity, however, has not been without impact: Dust emitted by the dunes routinely blows toward the nearby Nipomo Mesa area, violating air quality standards for particulate matter and posing a public health threat to residents.

Last year, the Oceano Dunes SVRA was issued an Order of Abatement, which requires the development and implementation of a management plan to bring the park’s dust emissions back into compliance with State and Federal air quality standards within four years. Now, with new funding from the California State Parks Off-Highway Vehicle Division, Gillies and several other DRI researchers – Vic Etyemezian, Ph.D., George Nikolich, and John Mejia, Ph.D.—are continuing a long-term effort to help park officials understand and manage dust emissions from the Oceano Dunes. But in order to stop the dust, it would help to know how it forms, and this is still a bit of a mystery.

Researchers measure dust emissions at Oceano Dunes.

The source of the problem

“Dunes are always sandy, but they aren’t normally dusty; at least not to this extent,” said Gillies, who has worked at the Oceano Dunes since 2010. “Part of our research is to actually come up with the scientific reasons why the dunes are so dusty.”

Neither the park nor the town has long-term air quality data to show what conditions were like prior to the presence of vehicles, says Gillies, but there is evidence that suggests that the presence of the vehicles exacerbates the problem. Gillies and Etyemezian hypothesize that the dust emitted under elevated wind speeds could be a result of the re-working of the dunes by the vehicles and re-shaping of the dunes by coastal winds.

Researchers do know that dust is released from the dunes through a natural process called saltation, in which wind-blown sand particles bounce along the surface of the dune, kicking up smaller particles of dust – and that holding the sand in place helps to prevent that dust from being released.

“When the wind blows the sand across the dune surface, it’s like all these little missiles of sand coming in,” Gillies explained. “That’s what kicks out the dust, and then the dust is dispersed by the wind.”

Tools of the trade

To help park officials identify major sources of dust, Gillies and his DRI colleagues are engaged in an effort to map out specific areas of the park where dust originates. This spring, they collected more than 500 dust emissions measurements in a grid pattern through the OHV recreation area using a tool called the PI-SWERL (Portable In-Situ Wind Erosion Lab).

“The last time we did such an extensive measurement of dust emissions at the Oceano Dunes was in 2013, so it was decided that we should go back this year to update the underlying emission grid and see if, or how much, it has changed,” Gillies said.

PI-SWERL at the Oceano Dunes

Pi-SWERL at the Oceano Dunes. Credit: Jack Gillies/DRI.


The PI-SWERL at Oceano Dunes. A flat blade several cm above the surface in PI-SWERL rotates creating a shear stress like the wind created when it blows across a surface, causes the sand to saltate and the dust is emitted. The inset shows the sand surface after a test. PI-SWERL sits on the metal frame to provide a stable surface for testing. Credit: Jack Gillies/DRI.

The PI-SWERL, which was developed at DRI by Etyemezian and Nikolich, measures the potential for dust emissions from real-world surfaces. It acts as a miniature wind tunnel to simulate the high winds that produce dust storms. The dust emissions measurements are fed into a computer model, developed in part by DRI’s John Mejia, which simulates the action of coastal winds and the subsequent dispersal of dust. Using this model, the team can help park officials identify “hot-spot” areas where dust originates, and target those areas for remediation.

The team has also installed a network of air quality monitors throughout the park, which monitor wind speed, wind direction, relative humidity, and particulate matter. These data are adding to their overall understanding of the spatial variability and strength of the dust emissions at the dunes.

“These data will help us answer questions like whether dust emissions levels are different on weekdays versus weekends, when human activity in the park is higher,” Gillies explained. “It will also allow us to see how things are changing over time.”

Researchers gather dust emissions data at the Oceano Dunes SVRA using the PI-SWERL. May 2019. Credit: Vic Etyemezian/DRI.

Researchers gather dust emissions data at the Oceano Dunes SVRA using the PI-SWERL. May 2019. Credit: Vic Etyemezian/DRI.

Seeking new solutions

As the DRI team works to answer underlying scientific questions about the Park’s dust problem, they are also engaged in efforts to help develop and monitor solutions. They are working with Park officials on various dust control strategies, such as the use of temporary sand fencing, and revegetation with native plants to help hold sand in place and trap moving sand.

“Our aim is to stop the sand from moving, because when you stop the sand moving, you essentially stop the dust from being emitted,” Gillies said.

They are guiding the creation of “vegetation islands” of native plants, similar to that which are found in undisturbed dune areas to the north and south of the SVRA. OHVs are excluded from these areas, as well as from large sections of the park where endangered California least terns and threatened Western snowy plovers breed and nest during spring and summer.

As new dust control measures are added, the team monitors the remediation sites to see if dust emissions levels are reduced. The goal, Gillies says, is to help the park develop a management plan that will bring them into attainment with the Federal air quality standard for particulate matter within four years.

“The park has been ordered to find a solution to this problem, and it’s a problem that has raised a lot of contention among people of the region,” Gillies said. ”There are a lot of people who enjoy OHV recreation at the dunes and their visits contribute to the local economy, and another contingent of people who live downwind of the park and really want to breathe clean air. So, it is an interesting project to work on, both from a scientific perspective and as a project that deals with real-world problems.”

Vegetation islands at Oceano Dunes

At the Oceano Dunes SVRA, native “vegetation islands” are being restored to help reduce dust emissions from the dunes. Credit: Jack Gillies/DRI.

About Jack Gillies: Jack Gillies, Ph.D. is a Research Professor of Geography with DRI’s Division of Atmospheric Sciences. Jack specializes in the physics of sediment transport by wind, and applies this knowledge to solve problems related to air quality. He grew up in Ontario, Canada, and holds bachelors, master’s and doctoral degrees in physical geography from the University of Guelph, Ontario. Jack began his career at DRI as a post-doctoral researcher in 1994, and has been a member of the DRI community for 25 years. To learn more about Gillies and his research, please visit: https://www.dri.edu/directory/5427-jack-gillies 

Researchers identify connection between more frequent, intense heat events and deaths in Las Vegas

Researchers identify connection between more frequent, intense heat events and deaths in Las Vegas

Photo: Hotter temperatures and longer, more frequent heat waves are linked to a rising number of deaths in the Las Vegas Valley over the last 10 years.


Las Vegas, Nev. (June 4, 2019) – Over the last several decades, extreme heat events around the world—particularly in the North American Southwest—have gotten hotter, occurred more frequently, and lasted longer. These trends pose significant health risks to the growing number of people making cities like Las Vegas home.

A new study by faculty and undergraduate students at the Desert Research Institute (DRI), Nevada State College, and Universidad de Las Americas Puebla traces the relationship between extreme heat and mortality rates, identifying a clear correlation between heat wave episodes and heat-related deaths in Las Vegas over the last ten years.

“Current climate change projections show an increased likelihood of extreme temperature events in the Las Vegas area over the next several years,” explained Erick Bandala, Ph.D., assistant research professor at DRI and lead author on the study. “Understanding recent extreme heat trends and their relationship to health hazards is essential to protecting vulnerable populations from risk in the future.”

Researchers analyze data on computer.

Erick Bandala, PhD (left), shows a graduate student the data he and his team analyzed for this study.

Urban areas of the Southwest are of particular concern because several factors compound the health-related risks of extreme heat events. The heat-absorbing properties of common materials like asphalt exacerbate already high temperatures in cities (called the urban heat island effect), particularly at night. What’s more, populations in cities like Las Vegas are growing rapidly, especially among those 55 and older, which means that more and more people are exposed to risk.

In this study, the research team analyzed two measures of extreme heat—heat index and excess heat factor—for the Las Vegas metropolitan area in the June, July, and August months from 2007 to 2016. Heat index (HI) accounts for how the human body reacts to surface temperature and relative humidity. Excess heat factor measures (EHF) heat wave intensity in relation to historic temperature trends to account for how acclimated the public is to a given temperature threshold. Because both HI and EHF incorporate the human body’s response to extreme heat, they are ideal metrics for assessing public health impacts, and both were shown to rise over the study period.

The annual average of severe heat events per year in Las Vegas also showed significant increases in this study, from an average of 3.3 events per year from 2007-2009 to 4.7 per year in the 2010-2016 period. These findings match historic trends, which show a steady increase in severity and frequency of excess heat in Las Vegas since 1980.

Strikingly, the number of heat-related deaths in Las Vegas map onto these trends: as heat wave intensity increases, the number of heat-related deaths does, too.

Graphs of heat index and excess heat factor.

Heat Index (HI) and Excess Heat Factor (EHF) are metrics that go beyond just temperature to also account for the human body’s response to heat. This study found that rising trends in these measures tracked closely with the number of heat-related deaths in Las Vegas.

“From 2007 to 2016, there have been 437 heat-related deaths in Las Vegas, with the greatest number of those deaths occurring in 2016,” explained Bandala. “Interestingly, 2016 also shows one of the highest heat index measures over the last 35 years. This shows a clear relationship between increasingly intense heat events in our area and public health effects.”

Bandala’s team found that the subpopulation particularly at risk of heat-related deaths is adults over 50 years old—76% of the heat-related deaths in the study period were individuals in this subpopulation. Of the deaths in this group, almost all individuals also showed evidence of pre-existing heart disease. Researchers note that these findings are highly significant given that the population of adults over 50 in Las Vegas is increasing, with more retirees choosing Clark County as a retirement destination.

Only 23% of heat related deaths occurred in the subpopulation of adults aged 20 to 50 years; interestingly, the most common pre-existing condition for this group was drug and alcohol use. More research is needed to understand how heat is impacting this segment of the population, Bandala noted, because though the number of deaths in this group is comparatively smaller, it is still nearly one quarter of heat-related deaths in the Las Vegas Valley. Additionally, this subpopulation includes economically active adults.

With more intense, more frequent, and longer lasting heat events projected in the coming years, the research team hopes that the trends identified in this study can assist local decision-makers in taking steps to protect the most vulnerable groups in Las Vegas.

“This research helps us better understand the connection between the climate changes we’ve experienced in Las Vegas and their impact to public health over the last 35 years,” Bandala said. “Ideally, this data analysis will help our community adapt to the changes yet to come.”

The full study, titled “Extreme heat and mortality rates in Las Vegas, Nevada: inter-annual variations and thresholds”, is published in the International Journal of Environmental Science and Technology. The study abstract and references are available here: https://link.springer.com/article/10.1007%2Fs13762-019-02357-9 

This study is based on work supported in part by the National Science Foundation, NASA, and the Desert Research Institute. Other members of the project team include Kebret Kebede, Nikole Jonsson, Rebecca Murray, and Destiny Green, all of Nevada State College; John Mejia of DRI; and Polioptro Martinez Austria of the Universidad de Las Americas Puebla. 

New study identifies atmospheric conditions that precede wildfires in the Southwest

New study identifies atmospheric conditions that precede wildfires in the Southwest

Reno, Nev. (January 3, 2018): To protect communities in arid landscapes from devastating wildfires, preparation is key. New research from the Desert Research Institute (DRI) in Reno may aid in the prevention of large fires by helping meteorologists and fire managers in the Southwestern U.S. to forecast periods of likely wildfire activity.

Each summer, from June through September, a weather pattern called the North American monsoon brings thunderstorms to the Southwestern U.S., with lightning that often sparks wildfires.

The new study, which published in the International Journal of Climatology, examined twenty common weather patterns that occur during the North American monsoon season, and identified relationships between certain weather patterns and times of increased fire activity.

One of the most problematic weather patterns, the team learned, was when dry and windy conditions gave way to lightning storms in May and June – a time when fuels tended to be at their driest and monsoon rains had not yet soaked the region with added moisture. When lightning storms were followed by another hot, dry, windy period, increased fire activity was even more likely.

“A lot of fire meteorologists know from experience that this is how things happen, but our study actually quantified it and showed how the patterns unfold,” said lead author Nick Nauslar, Ph.D., who completed this research while working as a graduate student at DRI under Tim Brown, Ph.D. “No one had ever really looked at large fire occurrence in the Southwest and how it related to atmospheric patterns.”

To identify problematic weather patterns, Nauslar and his team looked at monsoon season weather data collected from April through September over the 18-year period from 1995-2013. They then classified wildfire activity over the same period into days or events that were considered “busy” by fire managers in their study area, and used an analysis technique called Self-Organizing Maps to detect relationships between the two datasets.

In addition to identifying relationships between specific weather patterns and fire activity, their analysis also looked for patterns in wildfire occurrence and fire size throughout the season. Analysis of more than 84,000 wildfires showed that although July was the month that the most wildfires occurred, wildfires that occurred during the month of June (prior to the arrival of much monsoonal moisture) were more likely to develop into large fires. In July and August, when the heaviest monsoonal precipitation typically occurs, the percentage of fires that developed into large fires decreased.

“Our goal with this study was to provide fire weather meteorologists in the region with information to help inform fire forecasts, and I think we were able to identify some important patterns,” said Brown, Director of the Western Regional Climate Center at DRI.

Nauslar, who is now employed as a mesoscale assistant and fire weather forecaster for the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center in Norman, Oklahoma, hopes that the findings of this study will help fire managers in the Southwest to proactively identify periods when wildfires are more likely to occur, and to allocate firefighting resources accordingly.

“I think a lot of what we learned confirms forecaster experience about the types of atmospheric patterns that are problematic with regard to wildfire occurrence in the Southwest,” Nauslar said. “I hope that people in operations can really use this information, and help refine it and build upon it.

Other DRI scientists who contributed to this research included Benjamin Hatchett, Ph.D., Michael Kaplan, Ph.D., and John Mejia, Ph.D. The full study, titled “Impact of the North American monsoon on wildfire activity in the southwest United States,” is available online from the International Journal of Climatology: https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.5899


The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI serves as the non-profit research arm of the Nevada System of Higher Education. Learn more at www.dri.edu, and connect with us on social media on FacebookInstagram and Twitter. 

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