Sandy ocean-facing shorelines are constantly changing due to wind- and wave-driven currents, wave action, overwash, and aeolian transport. Vegetation contributes to the process by trapping sand to aid dune stabilization and growth. Satellite images of Head of the Meadow beach (Cape Cod National Seashore, Truro, Massachusetts) suggest that vegetation has been expanding over the last decade at the base of a bluff system. We mapped a ~300-m long section of the beach in late winter of 2020, 2021, 2022, and 2023 by collecting an average of 1,000 overlapping aerial images each year using a camera attached to a helium-filled kite. We applied structure-from-motion photogrammetry with ground-control points to create 5-cm horizontal resolution digital elevation models (DEMs) for each year with vertical accuracies of ~2 cm. We calculated erosion and deposition rates by differencing the DEMs and found that the small dunes at the landward edge of the beach, where vegetation had increased, were growing. Sections of the beach gained as much as 1.7 ±0.02 m of elevation between 2020 and 2022, and the vegetated band at the base of the bluff averaged about 0.30 m of deposition. The cumulative accretion rate in the vegetated regions amounts to about 6 m3/m per year, which contrasts with a long-term average erosion rate of about 0.05 m3/m per year along outer Cape Cod.

The data in this release map the beach and nearshore environment at Head of the Meadow Beach in Truro, MA and provide environmental context for the camera calibration information for the 2019 CoastCam installation that looks out at the coast shared by beachgoers, shorebirds, seals, and sharks. This is related to the field activity 2020-015-FA and a collaboration with the National Park Service at Cape Cod National Seashore to monitor the region that falls within the field of view of the CoastCam, which are two video cameras aimed at the beach. On March 4, 6, and 10, 2020, U.S Geological Survey and Woods Hole Oceanographic Institution (WHOI) scientists conducted field surveys to collect position and orientation information for the CoastCam cameras and map the field of view. Elevation data were collected using a real time kinematic satellite navigation system (RTK-GNSS) receiver attached to a pole and walked on the beach. Point data of the beach face were collected along transects and at periodic locations of plywood targets moved throughout the day within the CoastCam view. Grain-size analysis was performed on sediment samples collected with a spade along multiple profiles from the bluff base to the intertidal zone. Images of the beach were taken with a camera (Ricoh GRII) and a post-processed kinematic (PPK) system attached to a kitesurfing kite, and high-precision targets (AeroPoints) were used as ground control points. Bathymetry was collected in the nearshore using a single-beam echosounder mounted on a surf capable self-righting electric autonomous survey vehicle. Agisoft Metashape (v. 1.6.1) was used to create a digital elevation model with the collected imagery and this was merged with the bathymetry in MatLab (v. 2020) to create a continuous topobathy product.

The U.S. Geological Survey (USGS) provides operational forecasts of total water levels (TWL) and coastal change. Uncertainties around forecast TWL are based on the temporal and spatial range of observed beach slopes near the forecast site. This paper investigates other sources of uncertainty that are not accounted for, focusing on four beaches where the USGS has deployed remote cameras, and on outer Cape Cod, which has diverse bar morphologies. We find that the range of runup indicated by ten formulae is nearly as large as the variations caused by the range of beach slopes. A formula that accounts for bar morphology substantially decreases calculated runup, and might improve forecasts. Errors in the timing of forecast storm landfall generate uncertainties in TWL where tides are large. Analyses suggest that the effect of off-normal incident waves is relatively small. These results suggest opportunities for improving the TWL forecasts.