Multidecadal Changes and Trends in Global River Positions

Rivers play a central role in shaping the Earth's surface and ecosystems through physical, chemical, and biological interactions. The intensity and locations of these interactions change as rivers continuously migrate across the landscape. In recent decades, human activity and climate change have altered river hydrology and sediment fluxes, leading to changes in river position, or migration. However, a comprehensive perspective on and understanding of these recent changes in the rate of river position shifts is lacking. To address this knowledge gap, we created a continuous global dataset of yearly river positions and migration rates over the past four decades and analyzed trends. The global annual river positions were detected using Landsat-derived surface water datasets and processed in Google Earth Engine, a cloud-based parallel computation platform. The resulting river extents and centerlines reflect the yearly permanent position, corresponding to the rivers’ location during base flow. This approach improves the representation of position changes derived from geomorphological rather than hydrological processes. To robustly analyze river position changes across different patterns and complexities and at large scales, we developed and applied a global reach-based quantification method.

Results show that while alluvial rivers maintain stable positions in certain regions, others exhibit trends in the rates of position change. For instance, the Amazon Basin, which has experienced significant deforestation and hydrological modifications, has shown increased rates of river position change in recent decades, directly modifying active floodplains. In this presentation, we will discuss the advantages, limitations, and applications of the global yearly river position dataset, offer insights into the changing rates of river position, and highlight current and future impacts on one of Earth’s most vulnerable hydrologic systems.