Simulating the Compound Impacts of Climate Change and Sea-Level Rise on Coastal Shallow Groundwater Using an Integrated Surface-Subsurface Hydrologic Model

Author

Zhaoyi Cai, Old Dominion UniversityFollow

Date of Award

Fall 2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil & Environmental Engineering

Program/Concentration

Civil and Environmental Engineering

Committee Director

Xixi Wang

Committee Member

Carol Considine

Committee Member

Mujde Erten-Unal

Committee Member

Shahin Nayyeri Amiri

Abstract

As climate change intensifies and sea levels rise, coastal aquifers become increasingly vulnerable to interacting oceanic and terrestrial processes. This dissertation examines the combined impacts of climate change and sea-level rise (SLR) on coastal shallow groundwater using an integrated surface-subsurface hydrologic model, focusing on the low-lying Little Creek watershed (LCW) in Norfolk, Virginia. The SWAT-MODFLOW model, a coupled system, unifies land surface, streamflow, and groundwater processes, providing a comprehensive framework for watershed-aquifer analysis. Model parameters were derived from U.S. Geological Survey datasets, relevant literature, station records, and technical reports, followed by meticulous calibration. The validated model first simulated baseline groundwater levels based on historical climate data and a 2000 sea-level benchmark, then projected future scenarios to evaluate the impacts of: 1) climate change alone; 2) SLR alone; and 3) their combined effects.

The findings for the LCW indicate that under the most extreme climate scenario, annual groundwater levels could rise by up to 0.51 m, while the most severe SLR scenario could result in a rise of up to 0.53 m. Combined, these factors suggest a potential cumulative groundwater increase of 0.69 m, with spatial distribution patterns largely influenced by river networks, soil characteristics, and proximity to river channels and the ocean shoreline. This dissertation underscores the need for adaptive water management strategies that account for both long-term trends and immediate risks. Although annual-scale analysis provides insight into overarching patterns, it may obscure short-term extreme events, potentially underestimating the risks of flooding and waterlogging. Targeted planning is essential, particularly in vulnerable subbasins, coastal zones, and low-lying regions near rivers, to mitigate potential impacts on infrastructure, manage saltwater intrusion, and protect ecosystems.

The dissertation provides valuable insights into the hydrologic impacts of climate change and SLR; however, addressing the complex challenges of managing coastal groundwater systems will require ongoing research. Improving model accuracy, expanding data collection efforts, exploring socioeconomic implications, and developing practical adaptation strategies are essential steps toward building resilience in coastal communities facing the dual threats of climate change and rising seas.

Rights

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DOI

10.25777/67ga-k629

ISBN

9798302862433

Recommended Citation

Cai, Zhaoyi. "Simulating the Compound Impacts of Climate Change and Sea-Level Rise on Coastal Shallow Groundwater Using an Integrated Surface-Subsurface Hydrologic Model" (2024). Doctor of Philosophy (PhD), Dissertation, Civil & Environmental Engineering, Old Dominion University, DOI: 10.25777/67ga-k629
https://digitalcommons.odu.edu/cee_etds/215

ORCID

0009-0009-1570-9059