Remote Sensing-Based Assessment of Exorheic Siltation in Homonhon Island, Philippines Using Hyperspectral Imagery

Abstract: Mining activities on Homonhon Island, Philippines, have increasingly contributed to coastal water pollution and siltation, particularly during extreme weather events. This study investigates the influence of climatological factors—specifically precipitation—on mining-induced siltation using satellite-based remote sensing. Sentinel-2A imagery was employed to monitor and quantify changes in water turbidity and sediment deposition before and after typhoon events. Two spectral indices, the Normalized Difference Water Index (NDWI) and Normalized Difference Turbidity Index (NDTI), were applied to assess the extent of siltation across different time periods. Results revealed a notable increase in siltation areas following typhoons, with the year 2023 showing a surge of approximately 11 million square meters of affected areas, despite receiving only 23.9 mm of rainfall. This indicates that cumulative land degradation from mining operations may have heightened siltation susceptibility even under moderate precipitation. These findings highlight the critical role of satellite-based monitoring in supporting sustainable land use and coastal resource management in mining-affected regions.