The main objective of this dissertation was to investigate the impacts of human activities and climate control on hydrologic responses using the Integrated Hydrologic Model (IHM), which couples HSPF and MODFLOW. The study first evaluated the impacts of land use change and rainfall variability on hydrologic responses-such as streamflow, evapotranspiration (ET), groundwater ET, recharge, and groundwater heads-in the Anclote River basin (ARB), Florida. The results provided insights into the uncertainties in hydrologic responses due to rainfall variability. Secondly, hydrologic response flux changes were partitioned into anthropogenic causes, including groundwater pumping, irrigation, and land use change, by the IHM in the Trout Creek Watershed, Florida. Hydrologic response flux changes per unit of human stress flux change were calculated and assessed at mean annual and monthly scales, offering insights for projecting hydrologic changes due to anthropogenic stressors. For climate control, a three-stage precipitation partitioning framework was proposed to study climate impacts on mean annual groundwater ET across 33 gauged watersheds in west-central Florida using the IHM. The roles of groundwater ET in long-term water balance were quantified through four ratios, and the contributions of various climate variabilities to groundwater ET were determined, providing new insights into sustainable groundwater management. Moreover, the dissertation explored the development and application of a multi-scale framework for the IHM, enhancing simulation accuracy and efficiency across different spatial scales and facilitating better water resource management. Applied to the ARB, this framework demonstrated improved model performance in capturing hydrologic changes due to local human activities and climate variability. This research underscored the significance of integrated surface-groundwater models in accurately assessing hydrologic impacts for water resource management, especially in regions with shallow water tables. It advanced the understanding of human and climate impacts on hydrologic systems, offering valuable tools and methodologies for integrated water resource management.
Dingbao Wang, Committee Chair.
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