Analyzing Total Suspended Matter variability at the Ebro-Segre river confluence (North-East Spain) by satellite data

High-quality inland water is crucial for human life, as well as for preserving the biodiversity of the involved ecosystems and habitats. The implementation of adequate monitoring systems for inland water quality is requested by the EU Water Framework Directive, as well as foreseen within the Sustainable Development Goals of the 2015 Agenda of the United Nations. Ocean-color remote sensing may represent a useful tool to complement ground-based measurements, since it ensures synoptic view as well as a good trade-off between spatial and temporal resolution. Among the water quality parameters that can be retrieved by satellite, Total Suspended Matter (TSM) is one of the most relevant, because its fluctuations can affect light penetration and phytoplankton productivity, thus threatening the ecological status of inland waters. Optical sensors such as OLI (Operational Land Imager) onboard Landsat 8 and 9 and (MSI Multispectral Instrument) on Sentinel 2A and 2B, have already demonstrated their capabilities in providing accurate TSM retrievals with spatial resolution up to 20 and a sub-weekly temporal resolution, especially when jointly used. In this work, the long-term spatiotemporal TSM variability by satellite data has been investigated for a subset of the Segre and Ebro river confluence, just downstream the Mequinenza dam (province of Saragozza, North-East Spain). This area has been studied within the framework of the IDEWA (Irrigation and Drainage monitoring by remote sensing for Ecosystems and Water resources management) project, funded by the EU PRIMA program, to assess the impacts of irrigation activities (including drainage) on water quality within the Algerri Balaguer irrigation district. The assessment of TSM climatology, its inter-annual variability and the identification of potential extreme TSM plumes have been performed also for comparison with river discharge (Q) data (free available by the Confederación Hidrográfica del Ebro), measured close to the Mequinenza dam for the 2015-2022 period and the achieved results will be discussed in this work.