Dredging within or shallower than the Depth of Closure (DoC) has been identified as a critical driver of coastal instability, particularly in high-energy environments such as the San Felipe, Zambales coastline. This study integrates satellite-based shoreline monitoring, empirical modeling of wave transformation, and morphodynamic analysis to quantify the impacts of dredging near the Sto. Tomas River exit. Quarterly Sentinel- 2 imagery (2020–2025) was processed using a geodata science approach in Google Colab (Python 3.0), employing cloud masking, Normalized Difference Water Index (NDWI), and regression-based shoreline change analysis. These physical changes correlate with a negative sediment budget following the onset of dredging shortly before 2023 and afterwards, underscoring reduced sediment supply as a key mechanism of accelerated erosion. The study highlights the compounded risks of dredging-induced morphodynamic changes, wave run- up, and sea-level rise, which threaten coastal properties, ecosystems, and livelihoods; reflecting the high cost of unmanaged shoreline retreat. Importantly, the findings stress the inadequacy of current Philippine environmental impact assessments (EIA), which often rely on secondary data and fail to incorporate DoC-based dredging thresholds, sediment transport modeling, or wave transformation dynamics. By combining remote sensing, empirical 2D/3D modeling, and process-based analysis, this research demonstrates the necessity of integrating DoC criteria, sediment budget accounting, and high-resolution simulation into dredging project evaluations. Such approaches can provide more reliable predictions of coastal response, ensuring that regulatory frameworks evolve to protect vulnerable shorelines while balancing the demand for marine sand resources.

Keywords: Satellite Data, Nearshore Dredging, Coastal Erosion, Depth of Closure (DoC), Wave Propagation