Drought propagation as a complex process has compounding ecological and societal impacts, which are seen through various manifestations of deficits being translated through the hydrological cycle in a region. Drought propagation time as an estimate of lag between meteorological drought and hydrological drought, provides vital information for developing drought mitigation strategies in a region. In this study we investigate the drought propagation time in 1031 catchments across various climate zones of CONUS using SPI and SSI to characterize meteorological and hydrological droughts respectively. We investigated two methods to estimate propagation time, using a linear method of correlation analysis, and using a cause-effect based method employing Cross-convergent mapping from meteorological to hydrological droughts. Moreover, to understand the influence of various catchment and climate controls on drought propagation time, we use an interpretative framework for Randon Forest models used for predicting drought propagation time in subsets of catchments in different aridity classes. Our results indicate that while CCM as a method is effective in quantifying response sensitivity of hydrological droughts to meteorological droughts, correlation analysis provides more reliable depiction of overall propagation process due to its inherent considerations for accumulation of deficits. Through the interpretative framework, we found that catchments storage elongated the drought propagation processes in catchments of all aridity classes. While few variables showed similar effect on drought propagation time in different aridity classes, significant differences in the variables importance measures and functional relationships with drought propagation time were found when comparing catchments of different aridity class.
