The Bull Run Water Shed feeds into two reservoirs that are the source of Portland’s public water supply and a critical part of the area’s infrastructure. In August of 2023, lightning ignited the Camp Creek wildfire that burned over 2,000 acres within the southern portion of the watershed. Once contained and extinguished concerns about the effect the fire had on the region and the watershed were raised. Vegetation lost to the fire could lead to slope instability and significant land movement. If such events were to occur, they could introduce high levels of sediment into the watershed. This might jeopardize the water quality by increasing the turbidity or could change the flow and output of the system entirely.
The Portland Water Bureau has engaged in a multi-year plan to monitor the area affected by the Camp Creek Fire focused on evaluating and mitigating potential land movement that could affect the public water supply. Traditional surveying methods, while valuable, had proven insufficient for assessing the extent of this risk, prompting the bureau to seek a more advanced solution. The Bull Run watershed is a remote, densely forested gorge with steep, rugged terrain, making ground-based assessments extremely challenging. While many of the State and Federal Departments conduct and provide aerial surveys of the area, they are not conducted to provide high resolution, “tactical data”, of the specific area nor are they conducted often enough to be effective monitoring solutions for the site. Elevate consulted with the Portland Water Bureau to develop a data collection methodology that would provide the sufficient detail and temporal information needed for the maintenance of their system. As a result Elevate conducted a high-precision small, unoccupied, autonomous, system (sUAS or “drone”) based aerial survey of the South Bull Run watershed as part of the developed monitoring plan.
Orthomosaic image of the south Bull Run area of interest.
LiDAR derived pointcloud of the site, classified by elevation.
Using LiDAR and imagery, Elevate was able to collect data that could be used to create a high resolution, “bare-earth”, digital terrain model (DTM) of the area of interest. While the data collection period was timed to coincide when tree cover was at a minimum, LiDARs ability to penetrate vegetation was critical in this area, despite the devastation of the fire. The use of a sUAS allowed the Elevate Team to fly closer to the earth’s surface, increasing data density. Further, by flying into the valleys, Elevate collected data from the steep slopes that are not able to be collected from a traditional aerial LiDAR system. The collection of data from these high-slope areas was a critical requirement of our client. Classification of the LiDAR data conducted by Elevate was required to provide an accurate model of the land surface in the area. This method was not without challenges. Our team navigated thick undergrowth, crossing massive fallen trees, and scaling steep inclines to deploy our equipment effectively. With the access and help provided by the Portland Water Bureau and using advanced aerial surveying techniques, we captured high-resolution LiDAR scans and imagery of the area, providing a comprehensive dataset to analyze post-fire landscape changes.
Image showing the ground return point density in points per square foot of the LiDAR data. Point density was over 9 points/sqft for most of the site.
“Bare-Earth” model of the site derived from the LiDAR data.
The Portland Water Bureau expressed confidence in the accuracy and completeness of our deliverables, which provided a level of detail previously unattainable through conventional methods. By equipping them with precise geospatial data, Elevate provided our clients a baseline to enable proactive monitoring and risk mitigation strategies. This project underscores our commitment to providing cutting-edge solutions that help clients address complex environmental challenges with accuracy, efficiency, and safety. The Portland Water Bureau has already contracted with Elevate to provide additional data from the site as part of the multi-year monitoring program and we are honored to play a role in protecting one of City of Portland’s most vital natural resources.