Author ORCID Identifier:
Date of Graduation
8-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Geosciences (PhD)
Degree Level
Graduate
Department
Geosciences
Advisor/Mentor
Cheng, Linyin
Committee Member
Peter, Brad
Second Committee Member
Stahle, David
Third Committee Member
Feng, Song
Fourth Committee Member
He, Yaquian
Keywords
Agricultural Impacts; Drought-Pluvial Transition; Landscape Controls
Abstract
Climate change is intensifying the frequency and magnitude of rapid transitions between drought and flood conditions, creating unprecedented challenges for water resource management, agricultural productivity, and ecosystem stability. This dissertation presents a comprehensive, multi-scale analysis of drought-pluvial volatility by 1) examining their observational uncertainties, 2) exploring their agricultural impacts, and 3) investigating landscape controls on these transition events across global and continental scales. Using the Event Coincidence Analysis with multiple observational datasets (GPCC, CRU, ERA5), this research provides a systematic global assessment of drought-to-pluvial (DTP) and pluvial-to-drought (PTD) transition frequencies from 1951-2020. Our results demonstrate that approximately 15.5% of meteorological droughts shift to pluvial conditions at the global scale, with similar rates for the reverse transitions, though substantial regional variations and observational uncertainties exist. In addition, the temporal analysis reveals an increase in drought-to-pluvial frequencies in several regions over the recent decades, with enhanced agreement among datasets for trend detection compared to the absolute frequency estimation. The agricultural implications of these transition events are next examined across the contiguous United States using crop yield data for corn and soybeans from 1980-2016. Our analyses reveal that the DTP events can partially mitigate drought-induced yield losses in the Upper Midwest, while the PTD events consistently exacerbate pluvial impacts, intensifying yield reductions by 10-15% in vulnerable regions, including the Northeast, Ohio Valley, and Southeast. Seasonal timing plays a critical role, with mid-season transitions showing the strongest influence on crop outcomes, particularly for corn during reproductive development phases. The third component of this dissertation investigates relationships between land use/land cover (LULC) patterns and drought-pluvial transition events using four decades of high-resolution satellite data (1985-2024). This continental-scale analysis reveals striking differences between the forest-dominated regions (transition rates < 20%) and the agricultural landscapes (rates >40%), providing empirical evidence for LULC controls on hydrological volatility. Crucially, the research identifies divergent landscape change patterns: regions with low drought-pluvial transition probabilities exhibit gradual, directional vegetation development toward improved water regulation capacity. In contrast, high-transition areas demonstrate chronic vegetation instability and simultaneous opposing land cover conversions (grassland-to-shrubland and shrubland-to-grassland transitions occurring concurrently across different locations) that perpetuates vulnerability of drought-pluvial transition events. This dissertation advances scientific understanding of compound extreme events by quantifying their global patterns, agricultural consequences, and their associations with the landscape. The findings highlight critical observational uncertainties that must be considered in climate model validation and risk assessment. Agricultural analysis shows that drought-to-pluvial events can mitigate drought-induced crop losses, while pluvial-to-drought transitions intensify yield reductions by 10-15% in vulnerable regions. The identification of LULC-hydrology feedback mechanisms provides new insights for developing landscape-based adaptation strategies to enhance resilience under accelerating climate change. In conclusion, these results show that drought-pluvial volatility poses a challenge, requiring integrated approaches spanning observational science, agricultural adaptation, and land management policy.
Citation
Li, Y. (2025). Spatial-temporal Analysis of Drought-Pluvial Volatility. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/5908
