Fluvial Dynamics of the Amazon River between Nazareth and Leticia: Potential Loss of Colombia's Sovereignty Over the Amazon River

The southern border of Colombia is delimited by the Amazon River, which defines the frontier between Colombia and Peru. Since the 1920s the border limit between these two countries has been defined by the river’s thalweg, however the river dynamics has caused changes within its geomorphology making this border line be constantly shifting due to changes in the river’s thalweg. This study analyzes the hydrodynamic behavior of the Amazon River and its geomorphological changes within a reach of 3.5 km between the towns of Nazareth (Colombia) and Leticia (Colombia). Through numerical modelling of the river reach, severe sedimentation processes in the left channel were identified, indicating major bed level changes within a 2-year simulation. These bed level changes indicate the appearance of sand bars in the Colombian portion of the river bed. The geomorphological changes shown in the model were validated through the analysis of satellite imagery, which indicates the erosion of the river’s right bank, and the sedimentation and contraction of the left bank. These geomorphological changes are causing the loss of river area within Colombian territory, hence meaning that Peru is gaining more river area. If the sedimentation processes continue within the left channel of the Amazon River between Nazareth and Leticia, island formations will increase and it will eventually close, therefore meaning a potential loss of Colombia’s sovereignty over the Amazon River.