Assessing the Propagation from Meteorological to Hydrological Drought in the São Francisco River Catchment with Standardized Indexes: Exploratory Analysis, Influential Factors, and Forecasting Strategies

Droughts are recurrent natural hazards that can strongly affect human activities and the natural dynamics of ecosystems. Strategies for drought risk management and mitigation depend on how rainfall shortages translate into water deficits in soil, streams, and aquifers. From this perspective, this paper investigates, with the use of standardized drought indexes, the propagation mechanisms from meteorological to hydrological droughts in the São Francisco River catchment, providing an assessment of the times of propagation and of influential physical and climatological factors. In addition, we explore a potential framework for predicting the times of propagation in locations with no streamflow information. The study results demonstrated that, while no marked distinctions in the meteorological drought statistics are verified across the study region, spatial patterns are observed in those of hydrological droughts, implying different mechanisms for drought propagation. Moreover, the prediction models demonstrated acceptable capacity, despite the complexity of the propagation physical processes. Hence, notwithstanding some modeling limitations, the proposed approach may constitute a useful auxiliary tool for hydrological drought forecasting and early warning at regional scale.