The Stardardized Soil Moisture Index (SSI) shows hydrological status at a basin scale at a resolution of 1 km. This index integrates satellite soil moisture data from the past 12 or 24 months from a specific point. Thus, it captures the effect of slow hydrological proccesses such as as snow melting or irrigation, providing a deeper look to precipitation data.

When applied over the Catalan river basins, the average of the index increases during wet periods (for example, after the Gloria Storm in January 2020), or decreases during dry ones (as the drought between February 2022 and February 2025).

As SSI it is not site-calibrated and relies only on satellite data, it provides a high-resolution drought monitoring tool with a global potential, paving the way for accurate assessment in data-scarce regions.