UAV Benthic Habitat Mapping Overview

Hoop Pole Creek Project

Mapping the distribution of different bottom habitats is critical to effectively protect and manage estuarine resources. Because of this and to aid in facilitating shellfish harvest and aquaculture, the Division of Marine Fisheries maps and samples the benthic habitats within shellfish growing areas to determine habitat type, acreage and abundance of oysters, clams, scallops and submerged aquatic vegetation. To date, the division has mapped over 602,000 acres of the coastal estuarine waters from Little River in Brunswick County to the northern end of Roanoke and Croatan sounds in Dare County.

Traditional methods were time consuming and expensive. Historically, EBHM data collection was done with hand drawn paper maps in the field, which were then scanned and digitized in the office. More recently, the program transition to an iPad Pro system in the field to more accurately map utilizing Bluetooth GPS devices. This improved efficiency, but still required immense field time. Thus, the implementation of drone technology.

Numerous technologies are utilized in the UAS program. First and foremost are the airframes used for collection. DIT choose to utilize DJI copter solutions as the exclusive airframe option. The DJI Phantom 4 Pro was used for initial case studies. Subsequent flights within the program incorporated the DJI Mavic 2 Pro with Hasselblad Sensor. Additionally, GPS receivers, ground control targets, and the Environmental Systems Research Institute’s (ESRI) mapping platform, which includes Drone2Map, have been incorporated.

Cost savings and accuracy gains realized by the incorporation of DJI drone solutions were astonishing. Acreage mapped in a day increased 5900% for a two staff member team. Traditional methods averaged 10 acres per day, while the UAS produced 600 acres per day. Estimated savings for the small portion (7500 acres) of the EBHM study area projected to ~ $400,000.00. As this area is only a fraction for the EBHM area, the potential savings for this program alone are in the millions.

The orthomosiac map displayed here is the result of a habitat mapping project carried out with a DJI Mavic 2 Pro with Hasselblad Sensor. The project achieved a spatial resolution of 0.62 inches, incorporating 201 images.

Zoom and navigate the map to see the incredible detail visible in the imagery.

Zoomed in example of oyster habitat.

The path of the drone and location of the images taken can be viewed in this map.

This map is the resulting classification layer derived from the drone imagery. This project was completed with only a 10 minute drone flight.

The sky is truly the limit with this technology. When the initial groundwork was laid for this program, approximately ten programs were identified within DEQ that would benefit from this technology. That number is growing rapidly as every division within DEQ would like to implement the technology. Taking into account the savings possibilities realized by UAS DEQ operations thus far, this has the potential to save the state millions in data collection costs yearly.

Initial EBHM case studies highlighted the savings that are and will be realized with future adaptations of UAS technology. For instance, the S024 (lower Cape Fear Estuary) area that the EBHM staff have been mapping in, is 7500 acres. With traditional methods, that equates to 750 field days for a team of 3 at 10 acres per day. The UAS program has proven to be capable of 600 acres in two-hour window around low tide. Low tide is required for either method to capture the estuarine benthos. At this rate the UAS can complete the field work for the 7500-acre area in 12.5 days. The estimated savings potential realized from S024 alone is ~$400,000. Extrapolated coast wide, the EBHM program savings are in the millions. 

Short terms gains have been realized in efficiency and accuracy. Long term, this technology will revolutionize the way North Carolina collects environmental data.