Capitalizing on the surfcam phenomenon : a pilot study in regional-scale shoreline and inshore wave monitoring utilizing existing camera infrastructure

Driven by dynamic inshore wave climates, sandy beaches oscillate around long term mean trends at daily (storm events) to inter-annual timescales (regional climate cycles). Coastal imaging technology provides a practical means for sustained, autonomous beach morphology and inshore wave monitoring at high temporal resolution. However, existing, scientifically-proven systems are limited in their application due to cost and required infrastructure. A potential alternative has been identified in the existing surfcam networks operating at 100+ sites around Australia and many sites around the world. This work reports a critical evaluation of this new, low-cost monitoring method which has the potential to significantly expand spatial coverage of coastal behavior; capturing both real-time forcing (waves) and effect (shoreline change). In this study, seven embayed beaches in New South Wales, Australia, are used to examine the potential for a sustainable regional monitoring network using existing surfcam infrastructure to provide daily measurements of shoreline position and inshore waves at the break point. Surfcam image-derived shorelines are compared at daily frequency over 10 months at one site to co-located Argus image-derived shorelines and at monthly frequency over 18 months at nine camera sites to concurrent on-ground RTK-GPS surveys. Preliminary comparisons to Argus image-derived and RTK-GPS surveyed shorelines indicated promising qualitative agreement. A simple geometric correction was shown to significantly improve the surfcam-derived shoreline measurements. Surfcam-derived inshore wave heights and periods are compared to three months of concurrent hourly nearshore (depth ?10m) wave buoy measurements at two camera sites. Initial evaluation of the wave measurement capability suggests a consistent over-estimation of smaller waves and under-estimation of larger waves. It is suggested that these "bottom-heavy" measurements are due to pixel rectification error associated with obliquity from a single low-angle camera; and the high variability in measurements due to beach and wave type.6 page(s