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Modeling flood hazards and exposure in the context of sea-level rise: Implications for human, engineered, and natural systems

  • Author(s): Hummel, Michelle Ann
  • Advisor(s): Stacey, Mark
  • et al.
Abstract

Sea-level rise (SLR) threatens coastal communities by increasing flood exposure for people, homes, businesses, and critical infrastructure. In order to protect residents and the infrastructure systems on which they rely, coastal communities will need to plan for and adapt to higher sea levels and increased flood hazards.

This dissertation contributes to the understanding of SLR impacts on human, engineered, and natural systems. More specifically, the text addresses three important aspects of SLR adaptation: the need for data-driven methods to inform regional SLR adaptation networks, the impacts of SLR on critical infrastructure and service disruptions, and the influence of coupled SLR, precipitation, and storm surge on coastal groundwater aquifers and flooding.

Many collaborative networks aimed at promoting SLR adaptation at the global, national, or regional scale are primarily based on geographic proximity or voluntary participation and are not grounded in any quantitative assessment of shared vulnerability. The first part of this dissertation presents a method to group communities based on similar SLR exposure variables using statistical cluster analysis. The method is applied to cities and counties in the San Francisco Bay Area to demonstrate the usefulness for developing regional SLR adaptation networks.

In coastal communities, critical infrastructure assets, such as wastewater treatment plants, are susceptible to flooding due to SLR. However, the extent and progression of this exposure and the impacts on service disruptions are poorly understood. The second part of this work presents a geospatial analysis of wastewater exposure to SLR-induced marine flooding at the national scale and a similar analysis of SLR-induced groundwater flooding at the regional scale in the San Francisco Bay Area. Overall, hundreds of wastewater treatment plants could face flood disruptions due to SLR, which could lead to a loss of wastewater services for millions of residents. In some cases, groundwater is more of a threat than marine flooding.

To understand the potential impacts of SLR on coastal groundwater aquifers and flooding, most previous studies have used steady-state methods and have focused on SLR and other climate factors, such as precipitation, separately. However, the strong coupling between precipitation and other weather variables that influence coastal water levels suggests a need for multivariate approaches. The final part of this dissertation describes the use of a copula approach to correlate precipitation with wind speed and atmospheric pressure. These variables are then used to determine changes in water levels due to wind setup and pressure-driven surge under current and future climate scenarios. Forcing a groundwater model with this data provides insight into the potential for a narrower unsaturated zone and groundwater emergence.

Together, these chapters explore the local disruptions and regional impacts of SLR, as well as the coupled processes that lead to flooding.

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