Osprey’s View of a Curious Natural Perched Beach, Guilford, CT - µUAS Aerial Mapping

Keywords: Natural Perched Beach, Theodolite and µUAS Surveys, Beach profile volume comparison.
Abstract Type: Poster Abstract

Abstract

Osprey’s View is a pilot project focused on evaluating viability and utility of engaging µUAS (micro drones) for coastal wetland monitoring, mapping, and 3D Modeling of a Natural Perched Beach located at Chaffinch Island Park, Guilford, CT. The Study Site comprises a salt marsh wetland with a curious "perched beach" deposit that rests atop and back from a natural wetland shoreline. This curious perched beach is anomalous in that loose sandy beach deposits usually reside at the shoreline in front of salt marsh wetland systems.

Google Earth views of the Perched Beach show a landward retreat ~60m in just 10 years. Theodolite and µUAS Mapping transects/surveys yielded comparable beach volumes. Both Theodolite and Aerial µUAS transects extend across the full beach width (~20m). Theodolite Transect Volume calculated to 9.10m3, and µUAS Transect Volume calculated to 9.14m3±0.36m3. Both Survey techniques were tied to a common set of ground control points using a precision GPS/RTK. In addition to a cross-beach "slice" from which volumes were extrapolated (traditional Theodolite technique), the µUAS mapping allowed for the entire 20m wide by 200m long by 0.6-1m high beach deposit volume to be model/calculated (1,107.38m3 ±58.26m3) with Pix4D Structure from Motion (SfM) software.

We demonstrated that the two methods are equivalent with similar calculated volumetric results. Unlike the single “slice-extrapolated” Theodolite volume, the µUAS/SfM technique also allows for the entire beach volume to be calculated, and as such is a far more efficient and effective survey technique to use in monitoring open area coastal landscapes.