Evaluation of the influence of systematic components on drought indices under climate scenarios in the upper basin of the Ángulo River, Michoacán

Abstract

This study evaluates the effect of deseasonalization and trend removal in precipitation, streamflow, and groundwater level series to improve drought index accuracy (SPI, SDI, and SGI) in the upper Angulo River basin, Michoacán. SARIMA models were applied to isolate genuine hydrological anomalies, comparing indices from original and adjusted series. Results show that processed indices exhibit greater sensitivity and realism in detecting meteorological and hydrological droughts, avoiding biases from seasonal patterns and long-term trends. It is concluded that these processes are essential for accurate drought characterization in basins with high seasonal variability.