Climate Science and Policy

Coastal dunes provide a nature-based approach for mitigating flooding and erosion hazards for coastal communities. They can protect valuable coastal infrastructure while maximizing ecosystem services and restoring the historical landscape of shoreline environments. In Oceanside, California, ongoing sea-level rise (SLR) and chronic sediment loss have created an urgent need for shoreline systems that can retain sand and maintain coastal resilience, prompting the creation of a Dune Restoration Pilot Study. To quantify the benefits of this and other coastal dune projects, monitoring of dune and beach profiles is needed to determine how resilient dunes are to various environmental forcings (e.g., waves, wind, sea-level change). Existing spatial mapping tools tend to be expensive to deploy and lack standardization. Moreover, the dynamic nature of coastal dune systems with coupled changes in the beach profile requires frequent sampling in space and time. To address this gap, this study develops and evaluates a novel mobile spatial data collection methodology using smartphone-integrated LiDAR and RTK positioning technology as a low-cost, accessible alternative to conventional aerial and vehicle based surveying during the City of Oceanside's Dune Pilot Study. The proposed framework is designed to enable a single organization to oversee the full monitoring pipeline from field data collection to spatial processing without outsourcing, increasing both efficiency and consistency across monitoring cycles. Results demonstrate that the mobile methodology can produce digital elevation models (DEMs) with spatial accuracy within acceptable thresholds for coastal change detection, yielding quantifiable measurements of dune accretion and erosion over the observation period. Volumetric and cross-sectional analysis of collected point cloud data reveal early-stage sediment accumulation consistent with successful dune establishment, providing an initial performance baseline for the pilot site. These findings underscore the viability of iPhone and RTK platforms as a standardizable monitoring tool and highlight the importance of quantitative spatial methods in communicating the measurable value of nature-based coastal adaptation strategies amid ongoing climate variability.