Abstract
Drought is one of the most complex extreme hydrometeorological phenomena to study and affects extensive regions worldwide. This study aimed to characterize droughts in the state of San Luis Potosí, Mexico. The analysis employed the parametric Standardized Precipitation Index (SPI), based on the two-parameter Gamma distribution. Drought intensity, magnitude, and duration were estimated at a 12-month accumulation time scale (SPI-12) based on records from 194 climatological stations covering the period 1955–2017. Multivariate statistical techniques were applied to identify the main precipitation patterns and the dominant modes of SPI-12 variability. The first two EOF modes explained 67% of the total SPI-12 variance (46% and 21%, respectively), and 14 and 11 drought events were identified for these modes. Significant spatially contrasting associations between the El Niño–Southern Oscillation (ENSO) and drought occurrence and spatial extent were identified. Drought conditions in the Altiplano and Centro regions were more strongly associated with La Niña, whereas the Media and Huasteca regions showed stronger associations with El Niño. Furthermore, the potential utility of SPI-12 as an explanatory covariate for changes in monthly runoff volume records was demonstrated for the Verde and Gallinas river systems, with significant Kendall’s tau correlations of 0.330 and 0.380, respectively. The findings provide a basis for improving drought characterization and understanding of its spatiotemporal variability in the region, while offering valuable information to support the development of effective planning, adaptation, and mitigation strategies.