In this study, we use numerical experiments with a simple water balance model to understand the roles of key climate characteristics in hydrologic drought propagation and the consequence of human responses to drought events under different climates. The experiments use climate inputs from a range of places with a hypothetical catchment of fixed properties to study drought propagation under different climates. Three drought propagation mechanisms are identified that produce hydrologic droughts with differing characteristics. The first mechanism involves seasonal groundwater recharge cycles, which persist during low rainfall periods, resulting in shorter hydrologic droughts compared to meteorological droughts. The second is characterized by seasonal groundwater recharge cycles that are suppressed during low rainfall periods, resulting in longer hydrologic droughts than meteorological droughts. The third is exemplified by a lack of seasonality in groundwater recharge and a strong control of precipitation over groundwater recharge, resulting in hydrologic droughts of similar duration as meteorological droughts. The roles of seasonality, climate aridity, and timing of precipitation in producing these different drought propagation mechanisms are studied. The timing of precipitation is found to have the most significant impact. Furthermore, modeling experiments are performed to understand the role of climate in the interaction between short and long time‐scale human activities in response to droughts and the effect of the common practice of groundwater pumping during drought events on long‐term groundwater depletion. Interestingly, climates with high interannual variability of precipitation are found to be associated with less groundwater depletion than the climates with low interannual variability.

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Drought impacts on the society and environment are influenced by how droughts propagate through the hydrologic cycle; however, the physical processes involved in drought propagation are not well understood. In this study, a physically based hydrologic model is used to understand the drought propagation mechanisms and their controlling factors in multiple watersheds selected from different regions of the contiguous United States (CONUS). The characteristics of hydrologic droughts are found to be significantly different in three regions of the CONUS: (1) western U.S. watersheds have long and intense streamflow droughts, (2) Great Plains and southwest U.S. watersheds have low intensity and duration of streamflow droughts, and (3) eastern U.S. watersheds have short but intense streamflow droughts. This spatial pattern of hydrologic drought characteristics is found to coincide with the pattern of climate properties. Highly seasonal recharge driven by winter precipitation or snowmelt leads to longer streamflow droughts in the western United States; whereas humid climate with low seasonality in the eastern United States leads to shorter streamflow droughts. Furthermore, the storage-discharge relationship is identified as a key watershed property which controls the intensity of hydrologic droughts. Higher sensitivity of baseflow to watershed storage in the western and the eastern U.S. watersheds leads to more intense streamflow droughts in these regions. In the Great Plains and southwest United States, watersheds have a lower sensitivity of baseflow to catchment storage which, combined with the highly arid climate, leads to low variability in baseflow, and in turn results in low intensity of streamflow droughts in the region.

This study investigates the spatial and temporal patterns of multiple drought characteristics (duration, severity, and intensity) under different return periods during 1900–2012 in the Continental U.S. (CONUS). We find two significant patterns: Pattern I shows persistent droughts in western and eastern U.S. and the Great Plains, which experienced large variations in the drought characteristics over long time; Pattern II shows transient droughts in the interior of CONUS, which experienced short‐term variations in drought characteristics. Trend analysis shows that duration, severity, and intensity of droughts under the various return periods are increasing in most of the Pattern I regions. Moreover, spatial distributions of duration, severity, and intensity of more frequent and less severe drought events are found to be different from those of less frequent and more severe droughts in the same time period; trends in these drought characteristics at long and short return periods are different at some locations, showing the different trends of extreme and mild droughts.