Date of Award
8-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Civil Engineering
Committee Chair/Advisor
Dr. Abdul K. Khan
Committee Member
Dr. C. Prakash Khedum
Committee Member
Dr. Ashok Mishra
Committee Member
Dr. Charles Privette
Abstract
Droughts and associated changes in water availability are major hydroclimatic risks under climate change, with important implications for water supply, agriculture, ecosystems, energy production, and water-resource planning. These risks are especially relevant in the Southeastern United States, where humid subtropical conditions, rapid population growth, land-use change, physiographic variability, and recurrent hydroclimatic extremes complicate drought assessment and surface water management. This dissertation investigates drought-driven changes in water availability across multiple spatial scales through literature synthesis, climate-model evaluation, drought-characteristic analysis, hydrological modeling, and explainable machine learning. First, the dissertation reviews droughts in a warming climate, emphasizing the roles of precipitation deficits, rising atmospheric evaporative demand, soil-moisture depletion, altered runoff generation, sectoral impacts, and key assessment uncertainties. Second, it evaluates CMIP6 models’ ability to reproduce historical meteorological drought characteristics and project future drought changes under 1.5°C, 2°C, and 3°C warming using SPI and SPEI. Results show that CMIP6 models capture broad drought patterns but exhibit regional biases, while future projections indicate stronger drought intensification under SPEI, highlighting the influence of warming-driven evaporative demand. Third, the dissertation examines historical and future meteorological droughts across the Southeastern United States, showing that projected drought risk depends strongly on the selected drought index. Finally, SWAT+ and VIC simulations are evaluated against observed USGS streamflow to assess surface water availability. Results show that VIC provides more consistent regional performance, while SWAT+ performance varies more strongly across discharge classes and watershed settings. SHAP-based interpretation indicates that model performance is shaped by watershed characteristics and model structure. Overall, this dissertation demonstrates that drought risk and water availability are governed by interacting climatic, physiographic, land-surface, and model-structural controls.
Recommended Citation
Bhardwaj, Kunal, "Hydroclimatic Variability and Drought Driven Changes in Water Availability in the Southeastern United States" (2026). All Dissertations. 4320.
https://open.clemson.edu/all_dissertations/4320
Author ORCID Identifier
https://orcid.org/0000-0002-4006-408X