Dr. Ehsan Jalilvand (He/Him/His)

Hydro-Data Scientist
Hydrological Sciences (617)

What is your research focus?

My primary research focus is on incorporating human water usage as a dynamic variable into water cycle modeling. Life on Earth depends so fundamentally on water that our search for extraterrestrial life always begins with the search for water! A striking fact about water usage on Earth is that over 70% of freshwater resources are used for agriculture to grow food, and once used, it is turned into a form that is no longer readily available locally. For instance, when farmers pump groundwater to irrigate crops, the plants use the water and later release it to the atmosphere; the water then moves elsewhere, and it is uncertain when—if ever—it will return.

Another issue is the matter of time. While pumping is fast, recharging groundwater can take much longer. Isotope-tracing studies have revealed that farmers may be using groundwater recharged by rainfall thousands of years ago! So, it is very important to protect our precious water resources on which we and our ecosystems rely. To do that, we need to know where, when, and how much water is used—and here is where the problem arises. Humans make all of these decisions, and our models are not equipped to represent their behavior. We usually simplify the decision-making process by making assumptions that can introduce significant errors into our estimates. For instance, we assume that farmers start irrigation when soil moisture drops below a predefined threshold and stop when it reaches another exact level. In reality, they may simply observe a neighbor and replicate their actions or rely on generational knowledge, leading to decisions that differ significantly from our assumptions.

I believe we can understand this complex decision-making process by observing farmers' decisions over time and then incorporating those insights into our models. This is where long-term satellite observation comes into play. Currently, I am working on algorithms to monitor and understand these decision-making systems using thermal, optical, and microwave satellite observations. By applying machine-learning models, I aim to integrate human decision behaviors into large-scale water-cycle modeling systems like NASA's Land Information System (LIS).

How did you end up working at NASA Goddard?

Eleven years ago, I reposted a NASA Goddard story for its breathtaking image of Iran's Dasht e Kavir desert (top right; acquired by Landsat 7 ETM+). Recently, Facebook resurfaced that memory—and I was struck by how little I knew back then: I didn't even know NASA Goddard existed, let alone imagine I'd one day work there.

At the time, I was a first-year PhD student still searching for the right research question when I came across an interesting paper proposing soil moisture as a “natural rain gauge.” The idea was that soil retains a memory of recent rainfall, and thus satellite-observed changes in soil wetness can be used to estimate the amount of rain that fell earlier. Intrigued, I emailed the author (Dr. Luca Brocca), and we had some back and forth. Fast-forward one year, I found myself in Italy working with him as my co-advisor to extend that approach for my dissertation. Near the end of my PhD, we serendipitously realized the same method could estimate irrigation water use—and to my surprise, this application drew much more interest than my original PhD topic. So, I shifted gears toward irrigation water use estimation.

After I finished my PhD in 2019, I was still really excited about the topic and wanted to keep working on it. I reached out to several people in the small community working in the same area, just trying to connect and explore some options for building upon the work. One of those emails went to Dr. Ronnie Abolafia Rosenzweig, who's now a good friend. I didn't hear back for nearly three months and had almost forgotten about it when he finally replied, saying, “Your email got lost in the shuffle—I just found it again.” That late reply ended up sparking the longest long-distance collaboration I've had, which led to multiple new studies, including one with Dr. Narendra Das. That collaboration eventually opened the door to a postdoc position at Michigan State University and brought me to the U.S. in 2022.

Another study from that outreach introduced me to Dr. Sujay Kumar who offered me an opportunity to join NASA Goddard just over a year ago. Working with Sujay, we realized that irrigation is fundamentally driven by human decisions, yet our models barely account for this. So, we took a step back to address this foundational issue. Now, I'm focused on integrating human decision-making into large-scale water-cycle models—arguably the most challenging, yet exciting, scientific question I've encountered in my career.

Looking back, if you asked me how I ended up at Goddard, I'd say it was a blend of curiosity, luck, and meeting great people. One thing's for sure—I never set out to work here; chasing a problem, not an institution, brought me to this wonderful place and to these wonderful people, and I can't wait to see what challenges lie ahead.

What aspects of your work are you most passionate about?

I am very passionate about science communication and believe weaving a strong narrative with familiar analogy can help core concepts stick! At my American Geophysical Union (AGU) 2022 poster session, I illustrated how thawing permafrost fuels climate change by borrowing from the iconic Game of Thrones scene when the ice dragon breaches the ice wall, and an army of nightwalkers pours through. Permafrost, a frozen layer of the soil that remains frozen for more than 2 years has stored remains of plants and animals (ancient carbon) for millennia. Now global warming (dragon) is causing it to thaw (shatter the ice wall), exposing this ancient carbon, twice the size of carbon currently in our atmosphere, to decomposition which releases CO₂ and methane (unleashing the army of dead). Using this analogy helps me borrow the imagery, drama, and chaos of that scene to highlight the importance of permafrost thawing that can push our climate-system past a tipping point. Almost half of the people who stopped by my poster were from a completely different field that wanted to know what that dragon is doing on my poster! It somehow worked like a clickbait, drawing people in, and helped me to start a conversation, the only prerequisite was having watched GOT which was met by almost everyone! (Read the full story here).

Did you always know that you wanted to study Earth science and hydrology?

For a civil engineer, especially one whose peers are now mostly involved in construction management and design, using satellite imagery and working at NASA feels like a significant departure. Frankly, pursuing a Ph.D. in remote sensing was never part of my plan. However, towards the end of my master's degree, I enrolled in a course focused on the application of [Geographic Information Systems (GIS)] and Remote Sensing in hydrology. It was literally the last course I took. During this course, there were references to a class taught by Dr. David Maidment at the University of Texas at Austin. He generously made all his teaching materials openly accessible, and his compelling teaching style and engaging assignments sparked my interest, initially in GIS, and later in remote sensing applications in hydrology.

Thirteen years later, just a few months ago, Dr. Maidment was in Maryland and was invited to deliver a Terrestrial Water Cycle seminar for the Hydrological Sciences lab at NASA Goddard. I had the chance to meet him in person for the first time and tell him that it was because of him, and the way he prepared and openly shared his teaching material with the public, that someone thousands of miles away was drawn to this field and is now here at Goddard. He jokingly replied, 'I'll tell my wife all those hours I sat behind the computer resulted in something!'. I truly believe that going that extra mile, like his pioneering decision to openly prepare and share teaching materials, which was quite progressive at the time, can have a profound and far greater impact than one might ever imagine.

What is a fun fact about you?

I have loved designing ever since I was a kid, starting with car sketches and then creating interactive prototypes to demo website experiences (you can see a demo for map-based tourism platform here) and eventually building my own website. More recently, I've started crafting logos for every new project I launch. I never start with a fixed concept in my mind; the design evolves organically as I work. Here you can see two logos I designed for two of my projects. They may be simple, but they give each initiative its own distinct character.

What scientific challenge intrigues you the most?

I believe that human intervention in the water cycle has grown significantly over the last century. Yet, large-scale hydrological models often treat human water use (e.g., abstraction for irrigation) as pre-defined demands, rather than as dynamic variables influenced by human behavior, socio-economic factors, policy, etc. I think the behavioral component has been largely ignored, because it was considered a discipline far removed from hydrology and Earth science.

However, satellite remote sensing provides unparalleled capabilities to observe and monitor various human-induced changes. With long-term global satellite data, we can observe human decisions over time, associate them with specific locations, and identify connections and patterns. Integrating these behavioral predictions into hydrological models moves the field beyond purely physical modeling to more holistic human-water systems modeling. I believe this paradigm shift has the potential to truly transform hydrological sciences.

What do you like to do in your free time?

I love playing a variety of sports—CrossFit, rock climbing and most recently pickleball (which honestly, I love the most) among others. We also often go on family trips and hikes with my wife, Mahya (also a GSFC scientist), and my son, who is just over one year old.

One of our most unforgettable adventures was a 1,200-mile road trip across Alaska in a car with a rooftop tent. We hiked in an abandoned mining town, flew in a floatplane, and watched bears, mosses and even Orcas, among others, in a remote corner of the state—proof that, despite development, Alaska remains wild at heart. At the time, I was developing and validating a satellite soil moisture product for the far north, and getting out there in person profoundly enriched my work, giving me a grounded perspective of a terrain I usually only observe from space.