Kelp Survey North Beach Port Townsend WA

Welcome to the North Beach Kelp Survey project

Our objective is to monitor the state of the kelp fields in the study area by conducting periodic aerial photo surveys and processing them into map-ready ortho-photo mosaics. A time series of these mosaics will show how the fields vary throughout a year and between years.

This study will supplement other similar studies (read more... NKKelp.pdf) and could be useful in discussions about the Protection Island Aquatic Reserve expansion (read more... PIAR.pdf).

BACKGROUND

Efforts to study kelp beds in Washington have relied on satellite and aerial photography, which are expensive and difficult to collect in fine detail statewide.

We thought we could act independently to collect high resolution imagery of our local area. We had access to some UAVs and GIS mapping software. We could be ready at short notice when the tide and wind conditions were favorable. Our particular blend of tools and talents allowed us to plan and conduct the flights, then to process them into accurate map images. (see fishnet.png image below)

During the previous six months we developed our procedures. Each flight was constrained by the battery life of the aircraft so we defined zones within which to fly parallel paths. We had flights almost every month. The full resolution images showed lots of detail (see images below full_res1.jpg and full_res2.jpg)

In June we completed our largest collection so far, almost the full study area. (see images below latestMosaics.png, latestPartMos.png and LatestPhotos.png). This will be used as a baseline data set, with additional layers added each month. By this time next year, we hope to have a clear and compelling understanding of how our local kelp beds are faring.

THE TEAM

The team members are retired scientists who live in Port Townsend and visit North Beach regularly. Christopher Kelley is a marine biologist, Jeff Taylor an engineer and Joe Roubal a cartographer.

Our aircraft are DJI mini-pros. We fly at 20 m above the water, at a speed of 4 m/s. Pictures are taken at 2 second intervals. A typical flight lasts about 20 minutes and collects about 500 images. Each raw image is about 3000 x 4000 pixels and covers an area of about 18 m x 22 m (60 x 70 feet), resulting in a pixel size of about 7 mm. The ortho-corrected image is resampled to 2 cm in UTM coordinates and is about 900 x 1200 pixels.

Christopher uses ArcGIS and Photoshop to do the planning, visualizations and analysis. Joe uses Photoshop and EZ_Map (his own proprietary software) to perform the ortho-corrections and mosaicking.