Implementing a national-scale River Monitoring with Sentinel 2 images

Mapping river systems and their dynamics can enhance our understanding of the underlying geomorphic processes and their natural and anthropogenic drivers. Analyzing river morphological evolution, in particular, provides insights into historical, contemporary, and potential future river changes. This information can support river managers in identifying and prioritizing effective strategies for flood and geomorphic hazard management as well as for restoration programs. In Italy, the IRIDE project, funded by the Italian PNRR (Piano Nazionale Ripresa e Resilienza – “National Recovery and Resilience Plan”) and developed through a collaboration between the European Space Agency and the Presidency of the Council of Ministers of the Italian Republic, leverages available satellite constellations to establish an automated river monitoring system at national scale. This monitoring framework was designed using the Copernicus Sentinel-2 images (10 m resolution, 5 days revisit time) for medium-large rivers and will be further implemented with the upcoming IRIDE constellation (8 m resolution in multi-spectral bands + 3 m in panchromatic band, daily rivisit time). This contribution outlines the workflow developed in collaboration with the industry, showcasing key results that have supported various geomorphic analyses. The workflow involves: (1) generating a sequential structure of Disaggregated Geographic Objects (DGOs) to discretize rivers from upstream to downstream into ordered 500-meter-long units; (2) automating the generation of annual Active Channel (AC) masks—encompassing river water and sediment bars—using a global Convolutional Neural Network algorithm [1]; (3) performing monthly classifications of water, sediment, and vegetation within the annual AC mask via a data-driven algorithm tailored to the Italian territory; (4) analyzing the aggregated monthly classifications within the S2 archive (2017-2024) to develop indexes of geomorphic activities. The first results in the Po River network demonstrate that this monitoring system successufully capture planform mobility hotspots as well as episodic and progressive geomorphic change in each River reach. This systematic, nationally harmonized river observatory is unique and represents a pivotal step in using current satellite assets for wide-scale geomorphic analyses to support river management.

[1] Carbonneau, Patrice E., and Simone Bizzi. "Global mapping of river sediment bars." Earth Surface Processes and Landforms 49.1 (2024) - https://doi.org/10.1002/esp.5739 (2024)