Mapping The Environmental Footprint of Storm Daniel in Derna, Libya Using Satellite Imagery

Abstract

Storm Daniel triggered one of the deadliest and most destructive flood disasters in Libya's history, devastating the city of Derna after the failure of the Abu Mansour and Derna dams in September 2023. This study investigates the environmental impacts of the disaster using multi-temporal Sentinel-2 satellite imagery integrated with geographic information systems (GIS) and remote sensing techniques. A combination of land-cover classification, normalized difference vegetation index (NDVI) change detection, flood extent mapping, sediment transport analysis, coastal impact assessment, and digital elevation model (DEM) differencing was used to evaluate the environmental changes caused by the flood. The analysis revealed widespread flooding along Wadi Derna, extensive riverbank erosion, channel widening, large-scale sediment deposition, considerable vegetation loss, and severe damage to urban areas. Satellite imagery also showed a substantial sediment plume extending into the Mediterranean Sea, highlighting the close connection between upstream flood processes and coastal ecosystems. In addition, the findings suggest that the flood likely redistributed pollutants such as sediments, untreated sewage, petroleum products, and agricultural contaminants, which may have lasting consequences for soil, freshwater resources, coastal waters, and marine ecosystems. Overall, the study demonstrates that integrating satellite remote sensing with GIS provides a reliable and efficient approach for rapid post-disaster environmental assessment, offering valuable insights to support ecosystem restoration, disaster risk reduction, watershed management, and more sustainable urban planning in areas vulnerable to flooding.