Multitemporal Analysis of Amazon River Morphodynamics via Sentinel-2 MSI and NDWI: A Case Study of the Colombian–Peruvian Border (2018–2025)

The Amazon River’s intense geomorphological activity within the Colombian Amazon Trapeze presents substantial challenges for environmental management and the legal stability of the international border with Peru. Although the river’s regional dynamics are well documented, there remains a critical research gap regarding updated, high-resolution multitemporal assessments of the 116 km Colombian–Peruvian border stretch, where rapid morphological shifts directly threaten navigable sovereignty and local livelihoods. This study addresses this gap by analyzing the fluvial dynamics of the Amazon River between 2018 and 2025 through the integration of Sentinel-2 MSI satellite imagery and advanced spatial analysis in ArcGIS Pro. The methodology employed the Normalized Difference Water Index (NDWI) to extract water surfaces and quantify morphological changes—categorized as erosion, deposition, and stability—across contrasting hydrological periods: high-water (April–June) and low-water (August–October). The findings indicate that the river currently maintains a state of dynamic equilibrium, with overall morphological stability exceeding 70% throughout the study period. Specifically, the high-water channel exhibited remarkable stability exceeding 79%, whereas the low-water channel demonstrated significantly higher lateral mobility, culminating in a 22% erosion spike during the 2024–2025 interval. These localized processes, including bar migration and island formation, confirm active sediment redistribution despite the structural constancy of the main channel. By providing a precise quantification of recent morphodynamic trends, this research offers a vital technical contribution to territorial planning and border management. The results underscore the efficacy of Sentinel-2 for monitoring complex fluvial systems and highlight the urgency of sustained geomatic surveillance to mitigate potential territorial and ecological impacts in this strategic tri-national region