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Abstract As global mean temperature rises, extreme drought events are expected to increasingly affect regions of the United States that are crucial for agriculture, forestry, and natural ecology. A pressing need is to understand and anticipate the conditions under which extreme drought causes catastrophic failure to vegetation in these areas. To better predict drought impacts on ecosystems, we first must understand how specific drivers, namely, atmospheric aridity and soil water stress, affect land surface processes during the evolution of flash drought events. In this study, we evaluated when vapor pressure deficit (VPD) and soil moisture thresholds corresponding to photosynthetic shutdown were crossed during flash drought events across different climate zones and land surface characteristics in the United States. First, the Dynamic Canopy Biophysical Properties (DCBP) model was used to estimate the thresholds that define reduced photosynthesis by assimilating vegetation phenology data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to a predictive phenology model. Next, we characterized and quantified flash drought onset, intensity, and duration using the standardized evaporative stress ratio (SESR) and NLDAS-2 reanalysis. Once periods of flash drought were identified, we investigated how VPD and soil moisture coevolved across regions and plant functional types. Results demonstrate that croplands and grasslands tend to be more sensitive to soil water limitations than trees across different regions of the United States. We found that whether VPD or soil moisture was the primary driver of plant water stress during drought was largely region specific. The results of this work will help to inform land managers of early warning signals relevant for specific ecosystems under threat of flash drought events.
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Drivers and trends of streamflow droughts in natural and human-impacted basins across the contiguous United States
This dataset contains: Values for 42 variables related to topography, climate, vegetation, geology, and anthropogenic activities collected from 2001 to 2020. These variables were used to assess the drivers of streamflow drought deficit and duration across 2,550 stream gauges in the contiguous United States, including both natural and human-impacted sites. The computation method for each factor is detailed in Table 1. The dataset also includes trend analyses of drought duration and deficit from 1980 to 2020, performed using the Mann-Kendall test under three conditions: independence, short-term persistence, and long-term persistence. The complete analysis and findings are presented in Vicario, S.A., Hornberger, G.M., Mazzoleni, M., Garcia, M. (2025), "Drivers and trends of streamflow droughts in natural and human-impacted basins across the contiguous United States," Journal of Hydrology, DOI: https://doi.org/10.1016/j.jhydrol.2025.132908.
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- Award ID(s):
- 1923880
- PAR ID:
- 10573284
- Publisher / Repository:
- CUASHI Hydroshare
- Date Published:
- Edition / Version:
- 1
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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