Through Proxy and Scale: How Measurement Choices Shape Narratives of Shoreline Change and Vulnerability along the southern Irish coast

Shoreline change in Ireland is frequently managed using suboptimal evidence: monitoring coverage is spatially and temporally limited, and decision support often relies on a small number of indicators used as proxies for complex coastal behaviour. This paper argues that shoreline vulnerability is not only a physical condition but is also partly produced through measurement methods. Choices about what is observed, and at what spatial and temporal scales, actively shape the narratives constructed about shoreline behaviour, whether coastlines are interpreted as persistently eroding, highly variable, or capable of recovery, with direct implications for prioritisation and adaptation. The study examines how the use of different proxies and observational scales generate divergent or complementary interpretations of shoreline change, and what these differences imply for translating evidence into management-relevant guidance. It is based on a three-year, multi-method monitoring programme across five contrasting beach systems along the County Cork coastline in Ireland (2023–2025), integrating long-term aerial imagery and vegetation-line change, Sustainable Coastal Vulnerability Index (SCVI) outputs, repeated seasonal cross-shore RTK-GNSS beach profiles, high-resolution UAV-derived orthophotos and digital surface models, and targeted post-storm assessments following major events.

A comparative narrative analysis is used to evaluate how each monitoring method characterises coastal change at each site. Results show that long-term shoreline proxies and derived change rates can mask more recent acceleration trends, regime shifts, or hotspots of erosion, particularly where accretionary and erosional phases offset each other over extended time periods or where anthropogenic modification constrains proxy behaviour. High-resolution field and UAV-based measurements reveal that many sites are dominated by cross-shore and alongshore sediment redistribution rather than uniform shoreline retreat, with erosion and accretion occurring simultaneously in different areas, and at recurring hotspots linked to access paths, structures, and channel dynamics.

Comparison with SCVI classifications demonstrates that index-based vulnerability assessments are effective for broad screening of exposure and receptors, but may overestimate or mischaracterise physical susceptibility where local sediment dynamics, management measures, or recovery processes are not represented. The research proposes a tiered, resource-aware monitoring framework. Repeated cross-shore profiles are shown to be sufficient for tracking seasonal dynamics and storm response in relatively uniform settings, while drone-derived surface models are most valuable where spatial complexity, structural controls, or management-relevant hotspots are present, provided that logistical and environmental conditions allow their deployment. By clarifying when proxy-based screening, profile surveys, or spatially continuous UAV products are most appropriate, the study provides guidance for designing efficient monitoring programmes that reduce interpretive bias and better support coastal adaptation decisions.