MATT DOZIER: Hey there, Direct Current fans. Hope you’re all staying safe and healthy out there. I’m currently recording this from my home studio, a.k.a. a coat closet that my cat is frantically trying to get into. I’m sure many of you are stuck at home as we weather this pandemic, so we’ve got a new episode for you to listen to — one that doesn’t have anything to do with COVID-19. Except in a way, it kind of does. In our last episode, we talked about how our National Labs are responding to the COVID-19 crisis, bringing scientific expertise and powerful research tools to the struggle to protect human life. That’s what the National Labs do. They try to solve problems, whether it’s in particle physics, or energy storage, or a worldwide health emergency. My guests in this episode are working on a problem that — like the coronavirus — has human health impacts on a global scale. AND like the coronavirus, it’s a problem that at its core is about our changing planet. It’s not a disease — this problem involves something that’s essential to life on Earth, and yet many of us take it for granted. I’m talking about water. And more specifically, how it moves from place to place. Where does our water come from? Where does it go? And what happens after changes in the water cycle lead to disaster? This interview was recorded at the American Association for the Advancement of Science, or AAAS, 2020 Annual Meeting earlier this year. So if it sounds weird to hear us talking at a gathering of thousands of people… yeah. It’s a little strange for me, too. Anyway. We’ll have another live episode from that conference coming shortly. Hope you enjoy it, and I’ll talk to you soon.

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DOZIER: Hi everyone, this is Direct Current, an Energy.gov Podcast. I'm your host, Matt Dozier, with the U.S. Department of Energy. We're here at AAAS in Seattle live on the Sci-Mic Studio, brought to you by This Study Shows. My guests today are Michelle Newcomer and Ruby Leung, thank you so much for joining me today!

RUBY LEUNG: Thank you for having us.

MICHELLE NEWCOMER: Yes, thank you.

DOZIER: I'd like to start by having you each introduce yourselves, just give us little brief introduction, tell us where you work and a little about your research. Ruby, we'll start with you.

LEUNG: OK, my name is Ruby Leung, I'm a Patel Fellow at the Pacific Northwest National Lab in Richland, Washington, which is not too far away from here. I'm also the chief scientist for the U.S.　Department of Energy's Energy Exascale Earth Systems Model. Thank you.

NEWCOMER: My name is Michelle Newcomer, and I am a research scientists at Lawrence Berkeley National Lab, and my research focuses on topics in hydrology, extreme event-driven disturbances, such as fires, and how those type of events impact our water in our environment.

DOZIER: So we're here today to talk about the future of water and wildfire. Now, to do that, I think we really need to start with water. We're in Seattle, a city that's surrounded by water. We're at a scientific conference, I feel like everywhere I go I see people holding reusable water bottles, we're constantly being told to drink more water — but we don't just drink water, right? We use it for many other things. So what are some of the other ways that we actually use water?

LEUNG: Yeah, indeed, water is used for many different purposes. So besides drinking there are also many other domestic uses. We're all familiar with uses like using water to water our lawn, and we also know that water is used for recreation, and also transportation. But they only make up about maybe like 5% of water use globally. The biggest part of water use in the world is actually agricultural use. So that accounts for about 85% of the water consumption worldwide. But besides agricultural use, water is also actually used for energy production as well. So, hydropower generation uses water — and that's another about 5% of the water consumption globally — but we know that actually even thermoelectric power generation can also require water for cooling, even though most of the water is returned to the stream. But during a drought year when you don't have enough water to draw from the river, that can also cause problems for thermoelectric power generation.

DOZIER: Michelle, what are some of the other ways that water plays a role on the local scale?

NEWCOMER: So, water is incredibly important in the environment, both as an economic driving as well as an environmental driver. Ruby mentioned agriculture, we store our water in groundwater. We pump that water for agricultural purposes. We also store water in reservoirs, that's an important energy storage facility. We use this water, for example, for dilution of contaminants we rely on our rivers as important features in the landscape that dilute contamination. However, that can be challenged, let's say, if there's an event that introduces new contamination into our water system. So we often hear that "dilution is the solution to pollution," and when we have droughts, for example, that really challenges our ability to rely on water for that type of service. Water also provides other environmental services, such as providing habitat for our migratory salmon. It provides our drinking water, so we rely on water for a variety of other services in addition to agriculture.

DOZIER: So I think we all learned about the water cycle in elementary school. It rains, the water going into the streams, rivers, goes to the oceans, evaporates back up into the clouds, and it's very simple maybe 3-4 step process. It's a little more complicated than that, isn't it?

NEWCOMER: Yes.

DOZIER: Tell me a little bit about your work in terms of how we understand the water cycle, and how it moves through the environment.

LEUNG: Yeah, indeed, because water is so integral to the human society and also to ecosystems. We all learn about the water cycle even in middle school, and we know that on earth most of the water is stored in the oceans. But the water than we can actually use for consumption is mostly coming from water over land, in the form of groundwater, but also water in the streams and in the lakes, but also soil moisture. So these are like big storages of water, but what's important to understand is not only the storages, but what goes in and out of the fluxes — and we call them the fluxes. So some of the fluxes are, for example, precipitation — precipitation can enter into the ocean or into the land, and that can increase the storage — but also what comes out of the land or the ocean. These are what we call evaporation and transpiration. We also care a lot about runoff, which is the flux that connects between the land and the ocean. So as a matter of fact, the most difficult part that we need to learn about is the flux. Because of our lack of complete understanding about the fluxes, there are lots of uncertainties in how we can model water cycle.

DOZIER: So, in your work, you are working to build computer models that take into account all of these fluxes, different storage things, tell me a little about how you go about doing that — so you want to understand completely this whole picture of the water cycle and other environmental processes.

LEUNG: Yeah, indeed. So when we model the water cycle, we start by understanding the physical processes that govern the storages and also the fluxes, and so we turn them into equations. And after we have the equations, then we try to solve the equations by putting them over a mesh that covers the earth, so not only we have a mesh that covers the earth, but also we have vertical columns for the atmosphere, vertical columns for the ocean, and vertical columns for the land. And then we try to solve these equations. So we turn the equations into computer codes, and in fact most of our models, we have over a million lines of code, and we solve these equations on big supercomputers. So this is generally how we model the water cycle. But one really important thing that we also add to our model is that now our water cycle is no longer just a natural water cycle, because human activities have been really affecting the water cycle. So about two-thirds of the rivers around the world are regulated by dams, and if we look at the U.S. alone, less than 10% of the rivers are running free to the ocean, so they are all kind of regulated. I mention about the important use of water for agriculture. Since the beginning of the 20th century, irrigated area has expanded by over 5 times. So now we need a lot more water to irrigate the crops, and so we get the water from surface water, but we also get the water from groundwater as well. So pumping the groundwater really affects the groundwater level, so all of these human impacts have been affecting the amount as well as the timing of the water cycle.

DOZIER: Right. Let's talk a little about some of the impacts that can have, when we as humans change the water cycle and affect it, and other factors also contribute to changes. That I think brings us to the other topic that we're discussing here today, which is wildfire. So Michelle, can you talk a little about what you've seen in Northern California, especially through your work, with the wildfires and their links to the water cycle.

NEWCOMER: Sure, so a lot of the work I've done related to wildfires is in Sonoma County, where they've experienced some of the most devastating wildfires — both in terms of economic losses and in lives lost. During 2017, those wildfires appeared overnight, and they spread very rapidly, and one of the challenges that emerged after these wildfires is, how do we now assess the environmental impacts? This includes water as an environmental impact. So, some of those impacts are also related to water quality. You can imagine that, when you have a burned landscape, you have ash, you have trees that are burned, you have houses that are burned. So that introduces both natural organics into the waterways, new types of nutrients, as well as metals and contaminants that are entering not only the rivers, but one of the unrecognized portions of this landscape in terms of changes in water and water quality is the groundwater. So after a fire, you can have major impacts both to your infiltration of water going into the ground, as well as water going into the rivers. That's both the quantity of that water and the quality of that water. And so what I do in my research, my team is leading research in building a team framework to go out into the field, and to be ready to go after these type of disturbances, to sample the water. So we have a team, and within days of those fires we were out there. We mobilized very quickly to take a watershed approach to our sampling. So the watershed is really this unique, defined boundary where water is within this one unit of the landscape, and when rain falls on that landscape, you can track a particle of water as it goes into the soil, mixes with that ash, it goes through reactions, and eventually makes its way to the stream and to the groundwater system. So our team is really taking this very broad, long timescale watershed approach to understand the changes in the water quality, the changes in the quantity of the water both in the surface and the groundwater, and using novel techniques — for example, looking at microbes as indicators of these type of changes. So we're really excited about the trajectory of this type of research.

DOZIER: What's it been like going out and doing this kind of rapid response water quality sampling in communities that have been ravaged by these wildfires?

NEWCOMER: It's often very difficult — first, logistically, you can imagine just the nightmare that people are experiencing there, the people who live there, and so trying to navigate a team really requires a lot of coordination with local agencies. So we did that, we coordinated with local agencies. We were able to access sites to start to perform the sampling, and this includes water sampling and ash sampling, but I think it's really impactful when you actually go to these locations, and you can see not only how much your research impacts the science, but impacts people who have now just experienced this type of disaster. So our team really took that in mind, being very sensitive to the nature of this, that we wanted to explore the science but also provide a service in terms of research for a specific issue they were dealing with.

DOZIER: When you're going out there, what are some of the sites that you pick to sample as you're trying to assess the impact of these wildfires on water quality?

NEWCOMER: We usually pick sites that are close to waterways, so tributaries, creeks, areas that have some sort of burn zone — maybe near the top of the watershed or at some location within the watershed. We also choose sites that are burned directly, where we can sample the ash, because the ash — that's your source of contamination. So when that ash either infiltrates and it leaches into the ground or it runs off into the river, that's the source where you know, "OK, this is the initial metals for example that are being introduced to the system. So we go across the entire watershed as a team, so we are sampling both the ash and the water.

DOZIER: So you're looking for hidden impacts of these wildfires that may not be immediately apparent. Obviously, we see the news footage of burned houses and homes and trees, but there's then potential invisible impacts in the form of groundwater. Now Ruby, we were talking earlier — there's also impacts beyond the immediate area of the fire, correct?

LEUNG: Mhmm.

DOZIER: Is that something that you're able to follow with your modeling simulations?

LEUNG: Yeah, indeed, but before talking about the other types of impacts of wildfires, it might be important to know what actually causes wildfires.

DOZIER: Sure.

LEUNG: And how they might change in the future. Right, because many of us get the anecdotal information that seems like wildfires have been increasing. So we have been seeing more wildfires in California, and recently we have also seen a big wildfire in Australia. So it's important to understand what conditions are actually favorable for wildfires. So we know that wildfires happen under the conditions when you have high temperatures — basically, hot and dry conditions are very favorable for wildfires. And in California, we know that hot and dry conditions are usually coming from a condition where you have a high-pressure system sitting over land and then you get these northeasterly flows coming from inland blowing over to California, and because the winds are coming from inland, so they are often dry and hotter compared to when you have flows that are actually coming from over the ocean, where they are moister and cooler. So under these kind of conditions, you actually get wildfires. And we know that actually based on data, over the last 30 years, the frequency for this kind of hot and dry conditions are becoming more favorable, and increasing over time.

DOZIER: More favorable for fires.

LEUNG: Yes, yes. More favorable for wildfires, yeah. And also when we project into the future of what might happen, we find that over California, a very interesting thing that happens in the future under warming, is that the timing and the amount of precipitation can change. So what we found in California, for example, is that there's a sharpened seasonal cycle. So we know that California has the Mediterranean type of climate, so we get most of our precipitation in the winter, a little in the fall, and a little in spring. But under global warming, we find that the wintertime precipitation will be amplified, but the precipitation in spring and fall will actually decrease in the future. So this sharpened the seasonal cycle of precipitation, and potentially can expend the length of the wildfire season in the summer into spring, and also into the fall season. So it's really important to understand that wildfires can change, and then as a result of that, we can also see other impacts of wildfires. For example, widlfires produce these small, tiny particles — we call them particulate matter. They have the size of about maybe like 2.5 micron, which is at least 10 times smaller than the diameter of your hair. And these particles can be picked up by the wind, and they can be blown downwind thousands of kilometers away from the wildfire location. And so they can affect human health, they can affect air quality, and also visibility. So besides the air quality and human health impacts, we know that wildfires can also change the vegetation cover. By changing the vegetation cover, you can also change how much of the sunlight is reflected by the land surface, and how the land surface exchanges the fluxes of energy and water with the atmosphere. So that can also provide kind of a long-term impact on the climate.

DOZIER: Right. I want to circle back to the value of this research, and what the focus is, and why it matters to people. So Michelle, you were alluding to it earlier, of what you can learn from studying this water quality after a fire. What are you hoping this can provide to people who are impacted by these sorts of natural disasters?

NEWCOMER: What I'm hoping this provides is, first, a methodology for how we approach research after natural disasters. I think it's really important that we develop better research and protocols for these type of events. Just to give you an example, after wildfires, there are no protocols for what to do in terms of water. There are a variety of agencies that often come in, they have different techniques, different ways of sampling, different ideas of what's important to sample. So there are no methods for us to work together, and I think that's a really important first step, is developing these type of protocols, and I think my team and I, we're really at the forefront of that. I think it's also important in terms of groundwater, thinking about — since groundwater is such an important feature for California, we rely on groundwater during drought years, we rely on it for agriculture, that we recognize the importance of groundwater for maintaining this type of water security, and that in the future, our research can help to push those type of methods and analyses forward.

DOZIER: Right, and then also at that local level, you're talking about resilience, here, as well.

NEWCOMER: Right. It's definitely resilience, and we think about how we can be resilient to wildfires, it's managing our water infrastructure, and making these pre-investments to disturbances so we're ready when a wildfire or other natural disaster hits.

DOZIER: Right, and decision-making, that's another focus — I know that you have a session coming up, Ruby, talking about specifically water and making decisions about how we use it. With your research, how does that help us better make decisions that set us up... either protect us from threats, being more resilient in the wake of disasters, that sort of thing?

LEUNG: Yeah, so, computer models are really important in this regard. We use computer models to help us better understand the water cycle processes, because computer models can be used to test hypotheses. But more importantly, computer models are also used to help us simulate and predict what will happen in the future. So with computer models we can look at, for example, the impact of human activities on the water cycle, but also projecting over longer term as well as predicting in the shorter term how much water is available, as well as looking into extreme events. So what is really important is, extreme events have outsized impacts on society. So for example, extreme events such as tropical cyclones or severe storms, they can cause flooding on the ground, but also drought can change in the future because of the warmer temperature that causes more evaporation from the land surface. So being able to predict the water available underground for consumption and withdrawal, as well as predicting how extreme water cycle processes might change in the future is really important to help us prepare for what might happen in the future — as well as managing the resources that we have.

DOZIER: Right. And we've talked a little about some of the ways the conditions around wildfire can then create sort of a feedback loop in terms of then producing, potentially, more wildfires. In terms of the ways in which your research helps us understand that, tell me a little bit about the feedback loop there, and the ways it's important to both have the modeling and also be collecting the data on the ground.

NEWCOMER: One of the most surprising findings that came out last year from our colleagues at Berkeley Lab, Faji Minah and Erica Cyrilla-Woodburn — they looked at how wildfire impacts groundwater storage, and I think one of the most interesting things from that is that wildfire can have sometimes surprising impacts in terms of increasing groundwater storage. And so while that was a modeling study, that's exactly where　I think　data is needed. We need data to look at these type of results, to really analyze what are these drivers of these type of changes, and data modeling approaches are absolutely necessary for this type of work. So even with water quality, for example, it's the same approach — we have models that simulate water quality, but we have to verify and validate with real datasets, and scientific interpretation of those datasets. We can't just rely on, you know, data being presented to the public and say, "There you go." We have to have actually a very rigorous back-and-forth between the models and data for this type of interpretation.

DOZIER: And what's the value been, then, of being positioned at National Labs — at Pacific Northwest National Lab and Lawrence Berkeley National Lab — in terms of the resources you have available, and the amount of other expertise within arm's reach, in terms of being able to have interdisciplinary research.

LEUNG: Yeah, I think we are quite fortunate to be working for the Department of Energy. There are lots of facilities and resources that we can use. For example, when I talk about modeling, we really need to have very big computers. So supercomputers are important for helping us to better resolve the processes that we have, and the Department of Energy is leading the initiative the exascale computers for the future. So that's very important, but at the same time, I can't agree with Michelle more in terms of the needs for data. We really need to go out and collect data, and DOE has a lot of different programs that help us to go to the field — we have research aircraft, we have laboratory facilities, and also going out to the field to collect in-situ type of measurements. So these data are very important for us to better understand the processes that we are trying to model, but also we can use the data to help us evaluate how well our models are actually capturing the important processes that we are trying to model. So we are constantly using these data to help us improve the model. So, the type of data that we need are actually many different kinds. Besides data over the land surface that Michelle talked about, there are also other types of data, for example, collecting information about the clouds — we have research aircraft that we can fly through the clouds and collect information about these tiny little cloud droplets and cloud ice that actually produce the precipitation. We also have instruments where we can measure the aerosols, the tiny little particles in the atmosphere that influence how much precipitation is produced by the clouds. So I think these are great facilities that we use a lot, combining model and observations.

DOZIER: Yeah. So there's a feedback loop then, there as well, in terms of collecting the data, improving the models, improving the questions you're going to ask.

NEWCOMER: Right, a feedback in model-data integration, but it also feeds into how we understand the water cycle, that groundwater impacts the ability of vegetation to survive during droughts, and then droughts then change the groundwater — so the feedback right there is very direct. The interdisciplinary nature of that is incredibly important, and we would not be able to tackle these problems without having this lab-type environment where we have researchers from ecology, from hydrogeology, biogeochemistry, all coming together to try and tackle these large problems that individuals can't tackle alone.

DOZIER: Well, thank you for joining me, I appreciate it very much.

LEUNG: Alright, thank you.

NEWCOMER: Yes, thank you.

DOZIER: That's it for this episode of Direct Current. Thank you to my guests, Ruby Leung and Michelle Newcomer. Thanks as well to AAAS for hosting us on the Sci-Mic Studio, brought to you by This Study Shows. You can find Direct Current at energy.gov/podcast, on Twitter @ENERGY, or wherever you get your podcasts. I've been your host, Matt Dozier, with the U.S. Department of Energy. Thanks for listening!

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