Date of Award

Fall 2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Committee Director

Hans-Peter Plag

Committee Member

Richard G. Whittecar

Committee Member

Hua Liu

Abstract

Global sea level rise (SLR) is one of the most immediate impacts of climate change, and poses a significant threat to low-lying coastal communities worldwide. The metropolitan region of Hampton Roads in Southeastern Virginia is one such community, and one where knowledge surrounding SLR is rapidly accumulating. However, most of the research is focused exclusively on surface water processes despite the presence of a shallow groundwater table closely connected to them. SLR will continue to cause the groundwater table to increase in tidally influenced areas of Hampton Roads, and thereby decrease storage capacity of the unsaturated zone.

This study investigates the spatial and temporal response of the groundwater table to SLR and precipitation. We choose a tidal watershed, West Neck Creek, in Hampton Roads was chosen to conduct a conceptual yet realistic simulation of the hydrologic cycle using historical precipitation data with SLR scenarios from 0 m (current) to 2 m in 1 m intervals. Groundwater infiltration from the land surface, recharge, and evapotranspiration are modeled using the Unsaturated-Zone Flow package with MODFLOW-NWT. Groundwater rise is simulated by increasing the stage of the tidal stream that drains the watershed. Precipitation and overland runoff are simulated using the surface water model SWMM. The two models are coupled to permit the exchange of boundary condition values at each time step.An ensemble approach is taken to test model sensitivity to a variety of parameters.

The findings of the study demonstrated the potential for the effects of SLR-induced groundwater rise to become a damaging hazard to Virginia Beach communities and ecosystems. Most of the potential damages arose from increased interactions of groundwater levels with subsurface infrastructure. Additional runoff was found to be of lesser concern, because the prevalent soils in West Neck Creek are characterized by slow infiltration rates. The results of the sensitivity analysis provided encouraging results, in that changes in parameters did not have excessively large effects on forcing variables. Overall, this study provides a foundation to guide future scientific and engineering efforts to mitigate and adapt to the increasing threat of SLR-induced groundwater rise.

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DOI

10.25777/qsft-gq17

ISBN

9780355621310

ORCID

0000-0002-0602-3196

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