Integration of UAV photogrammetry, in-situ measurements and X-band-based A-DInSAR for risk assessment in Malta

The study focuses on integrating multiple UAV surveys conducted at critical hotspots with significant stakeholder density and pressures. The objective is to develop and validate a government-operable workflow that fuses cm-scale UAV models with mm-scale X-band A-DInSAR and in-situ measurements for cliff-instability risk assessment. Case studies include St Peter’s Pool, which experienced a major collapse, and Il‑Madonna tal‑Aħrax, a culturally significant area. High-resolution UAV photogrammetry provides precise visual evidence of the collapse zone, enabling accurate mapping of geomorphological changes. To complement UAV data, tilt plate measurements are used, which have already detected significant ground displacement, confirming ongoing instability in the affected areas, particularly during a significant storm event. These in-situ observations are combined with archived and contemporary satellite radar datasets for a multi-temporal analysis consisting of in-situ measurements, cartographic resources (both historic (Tranchant et al., 2024) and contemporary) and state of the art A-DInSAR interferometric analysis, which is a novel approach for Government. The end goal is to produce ground deformation maps that can detect ground movement, verified with in-situ measurements. The methodology applied to these case studies can, if successful, be transposed into other applications critical to governance, such as monitoring of critical infrastructures, for example roadways. The overarching goal of Malta’s Public Works Department, through the application of these methodologies, is to assist policy makers in acting based upon best available technology and practices. The outputs will be hosted as georeferenced hosted layers, accessible to all relevant government or academic stakeholders.