West Coast Drone Mapping

Using UAS to measure eelgrass meadow health and extent over time

Student Authors: Owen Hussey, Tiffany Martinez, Bryan Malone (Foothill College), Jessica Reimann, Tou In Kwan, My-Thu Tran, Nick Repetto

Coastal ecosystems and eelgrass habitats provide important services to the marine environment, including primary production, carbon storage, nutrient cycling, habitat for fisheries species, and erosion control. UASs with high spatial resolution, temporal flexibility, and cost-effectiveness for repeat photogrammetry, afford a significant advancement in other remote sensing approaches for coastal mapping, habitat monitoring, and environmental management. They provide essentially on-demand remote sensing at low cost and with reduced human risk.

The DJI Phantom 4 Pro (left) and DJI Inspire (right) were our primary data collection tools for Summer 2022

Drone imagery will be collected at least annually in coordination with in situ samplings which will also be used to validate the imagery by ground-truthing across a range of points within each meadow. Because eelgrass extent in some regions is subtidal and challenging to visualize from the air, we utilize DJI Phantom 4 Pro (RGB) and DJI Inspire (multispectral) drones and related drone mapping technology through Esri Drone2Map. Each year, ideally we allocate 4-6 days at each site for each drone mission to maximize ideal conditions for collecting drone imagery, striving for lowest spring tides, and calm, bright conditions with roughly vertical sunlight.

Drone mapping locations for Summer 2022

For the Summer 2022 leg of this project, the team gathered drone data at multiple sites along the west coast, consisting of Coos Bay OR, Newport OR, Friday Harbor WA, and Bodega Bay CA. For each site, the goal was to work in conjunction with a local university team to gather data on the health and extent of eelgrass beds, these universities being Oregon State University (Coos Bay and Newport), Cornell University (Friday Harbor), and University of California Davis (Bodega Bay).

Our goal for this data collection was to gather the necessary imagery to create large, high resolution maps of the eelgrass meadows for later analysis. By using the DJI Phantom 4 Pro and DJI Inspire, we are able to produce maps not only in the RGB bands, but in the multispectral bands as well.

Aerial view of an eelgrass meadow, shown in both multispectral (left) and RGB (right)


Before setting out for the real deal, the team met for a practice fieldwork session, where they practiced the skills and tasks necessary for the field work, such as drone piloting, drone hand-catching, and collecting GPS points.


Coos Bay and Newport, Oregon

Upon arriving at the first set of sites in Coos Bay, the team met up with and collaborated with Oregon State University and the University of Oregon (Pictured Dr. Ryan Mueller, Dr. Lillian Aoki, et al.,) to collect data on the nearby eelgrass meadows.

If there was one thing to take away about the field sites in Oregon, is that you have to be ready to get muddy! For many of the Oregon field sites, waders were a necessary piece of gear.

In addition to being muddy, some sites also required long treks into the intertidal areas

Thankfully, the weather conditions were often ideal for drone work, semi-clear skies and low winds!

During downtime, the team also took the opportunity to teach the OSU students more about piloting drones!

In much the same way the SJSU team practiced during their prep session, teaching OSU began with an overview of basic drone operation and function

After all the data collection was done, so begins the process of cleaning up the gear and packing up for the next site!

The less glamorous side of fieldwork, equipment often had to be cleaned and washed after each location

Phantom 4 Pro Drone Footage in Coos Bay, OR

As busy as the research trip was, the team still found time to enjoy the scenery and take in some of the sights!


Friday Harbor, Washington

Since many of our mapping sites were located at offshore islands, motorboats became our primary mode of transportation to get to our target locations. A huge shoutout to our collaborators Dr. Olivia Graham and Katie Philipp from Cornell University, for not only facilitating the in situ sampling procedures but also piloting the boat to get us around.

Thanks to the wonderful weather conditions, all the drone mapping works were finished on schedule. The aforementioned drone practice fieldwork session had definitely prepared the team to handle various kinds of situations during the mapping process.

Sometimes pre-flight preparations had to done on the boat. There were instances where we had to install and anchor colored buoys as Ground Control Points, or GCPs, from the boat in order to record their GPS coordinates.

Since the boat had to be anchore slightly offshore, the team often had to carry tools and equipment to and from the beach. This was where wetsuits and waders came in handy.

Because of the aquatic nature of the Friday Harbor fieldsites, all the necessary equipment for the day had to accompany the team via boat

We also tried flying our drones at a relatively low altitude to better capture the distribution and density of the eelgrass. The quality of the captured images was visually impressive.

Not to mention that the scenic views there were absolutely gorgeous!

Some great drone-captured visuals of the harbor!


Bodega Bay, CA

The Bodega Bay team ensuring that the DJI Phantom 4 Pro propellers are properly locked in and ready to go. Luckily, Dr. Yang spent time in class and during the fieldwork training practicing this task, which is necessary to ensure a safe and stable flight.

The DJI Phantom 4 Pro has been our ol' reliable during these fieldwork days. It is also the drone that students from the Geography program are most familiar with, as it fairly easy to learn and a practical size.

It was a great day for flying in Bodega Bay!

The field sites were still muddy, but at least we had our waders!

This photo is a great example that displays the density of eelgrass in our research areas. Here the UC Davis students, led by Claire Murphy, and SJSU students are gathering sampling data and counting for population density.

To help maintain accurate sampling, the students use transects to ensure that they collect from the same locations at each site

Unfortunately, the weather doesn't always cooperate! The drone should not be flown during foggy weather without safety lights, as we could lose line of sight of the drone. This photo was taken as the drone returned to home!

A good rule-of-thumb; if you can't maintain sight of the drone, it's not safe to fly!

Due to the close proximity of the Moss Landing Marine Laboratory, SJSU students, like Jessica pictured here, were able to participate in the marine research with the UCD students.

For the purposes of this project, the collected eelgrass was analyzed and inspected to learn more about the current health of the selected eelgrass meadows

After a long day of fieldwork, you tend to be a bit muddy!

One of best parts of finishing a day of fieldwork, is enjoying a nice hot meal afterwards!

Take-off of the DJI Inspire 2 and the DJI Phantom 4 Pro


Student Testimonials

"Having never been on a research trip proper, I was thrilled to be able to join the drone mapping team for this project. Taking all the techniques and skills I've been learning about in books and lectures, and having the chance to apply them in a real-world application is both an exciting and fulfilling experience. The fieldwork in Coos Bay and Newport was an incredible time with even better colleagues. Despite the mud, wind, and occasional rain shower, our team never let it dampen our spirits. Having just learned about the practical applications of UAS only a year ago, I never expected to use them in my academics as much as I already have. Having been a core member on the Oregon leg of this summer mapping project, as well as recently earning my P107 UAS license, I look forward to what dronework the future holds!"

Owen Hussey SJSU, Geography MA

"One of my favorite parts of being a Geography student at SJSU is the opportunity to join in on field research alongside my peers and professors. I had not anticipated learning how to fly drones during my time in my graduate program - and now I am a certified UAS commercial pilot! I had a great time getting flying practice in during our time in Oregon, as well as enjoying all the scenic views! Whether it was rain or shine, our whole team had a positive attitude and it was clear everyone was eager to get to work, despite the early hours, muddy waters or attacking seagulls."

Tiffany Martinez SJSU, Geography MA

"It was truly an honor to participate in this drone mapping fieldwork project on San Juan Island. I was grateful to have the opportunity to utilize drones in mapping the distribution of eelgrass along several coastal areas. I was really amazed and impressed by the quality of the drone imageries after processing. Thanks to our partner team from Cornell University, I was also given the opportunity to assist in their marine sample collection process. I would say it was a very successful experience, not to mention that Friday Harbor is absolutely gorgeous and fascinating."

Tou In Kwan SJSU, Geography MA

"I had a fantastic time assisting with eelgrass bed drone mapping of Bodega and Tomales Bays. I felt the level of pre-trip training, planning and organization provided by Bo Yang, Kerry Rohrmeier and the SJSU team was great and it helped make for a very successful exercise. I will treasure the memories of the team spirit and collaboration of both the SJSU and UCD teams for some time to come."

Bryan Malone Foothill College, GIST

"The drone mapping field trip to Bodega and Tomales Bays was fantastic! I had hands-on experience flying the drone for mapping seagrass, as well as collecting seagrass samples. It gave me great inspiration to continue doing research related to drone mapping for the Ph.D. level. Thank you, Dr. Bo Yang, SJSU, and UCD teams for this great field trip!"

My-Thu Tran SJSU, Geography MA

"Before joining Bo on his research project, I did not have the slightest idea of what his work would entail or how I would be providing assistance to him in collecting data. I was mainly interested in the project because it involved utilizing drones in field research and the concept was a unique application I had only heard about previously from Jeffrey Miller in his GEOG 135 Field Methods course at SJSU. Before setting out to conduct our field work, Bo had noted that the weather, specifically the fog, hindered data collection at this site in the past. This was indeed the case when we stopped at the first location alongside the western coast of the Bodega Harbor. After relocating to the second and third sites south of Bodega Bay, however, the weather was not an issue. I unfortunately did not have an opportunity to fly either of the drones at these locations, but I did join the UC Davis team in collecting samples of seagrass in Tomales Bay. It was a fun and kind of messy process, but I realized the value of learning about seagrass growth for the sustainability of the local ecosystem. My two pieces of advice for those who collect research in this setting in the future are #1) wear sunscreen or sun protection out in the flats and open waters to protect your skin against sunburns and #2) distribute your weight across as much surface area as possible to avoid trudging through the mud (you will travel at much greater speeds by pushing on a large object ahead of you than if you place your full weight on your feet or hands alone). It was certainly an interesting experience, and I enjoyed it a lot more than I had at first originally anticipated."

Nick Repetto SJSU, Geography BA

"Working on the Bodega Bay eelgrass mapping project has been one of the most unique & fulfilling experiences I've taken part in! Our team was well prepared and, even when we encountered on-site difficulties, we were able to collect great data and adapt our plans smoothly and have a good time while not working. Alongside guidance from UCD team members, I was able to assist with collecting eelgrass samples as well as process them for further analysis. This hands-on work proved to be incredibly satisfying after a day of fieldwork, and gave our team an amazing look into all aspects of our shared project. The new skills I have learned (as well as the exercise I had going through the mud!) and the memories our team made while traveling are invaluable."

Jessica Reimann SJSU, Marine Biology BA

Project performed in collaboration with:

  • Smithsonian Marine GEO
  • University of Central Florida
  • Citizen Science GIS Group
  • Cornell Univeristy and the Friday Harbor Marine Lab
  • UC Davis and the Bodega Bay Marine Lab
  • Oregon State University

Special Thanks to:

  • SJSU Research Foundation Level-up Grant
  • SJSU College of Social Sciences Student RSCA Grant
  • SJSU Spatial Analytics and Visualization (SAVI) Center

Join the Geography program at SJSU to participate in opportunities just like this! Visit sjsu.edu/geography to learn more.

SJSU URBP Faculty: Bo Yang, Kerry Rohrmeier, and Ahoura Zandiatashbar

For any questions, please contact: bo.yang02@sjsu.edu

The DJI Phantom 4 Pro (left) and DJI Inspire (right) were our primary data collection tools for Summer 2022

Aerial view of an eelgrass meadow, shown in both multispectral (left) and RGB (right)

In addition to being muddy, some sites also required long treks into the intertidal areas

In much the same way the SJSU team practiced during their prep session, teaching OSU began with an overview of basic drone operation and function

The less glamorous side of fieldwork, equipment often had to be cleaned and washed after each location

Because of the aquatic nature of the Friday Harbor fieldsites, all the necessary equipment for the day had to accompany the team via boat

Some great drone-captured visuals of the harbor!

To help maintain accurate sampling, the students use transects to ensure that they collect from the same locations at each site

A good rule-of-thumb; if you can't maintain sight of the drone, it's not safe to fly!

For the purposes of this project, the collected eelgrass was analyzed and inspected to learn more about the current health of the selected eelgrass meadows

One of best parts of finishing a day of fieldwork, is enjoying a nice hot meal afterwards!