Advance the practical application of statistical and other analytical techniques that can be used to assess the vulnerability of built and natural environments to the impacts of coastal flooding in a changing climate. This effort constitutes a substantial expansion upon work conducted under the Limited Scope project RC-2335, “Advancing Best Practices for the Formulation of Localized Sea Level Rise/Coastal Inundation ‘Extremes’ Scenarios for Military Installations in the Pacific Islands.”

Under RC-2335 a sequence of analyses focusing on nonstationary extreme value analysis (EVA) that enables the Generalized Extreme Value (GEV) location and scale distribution parameters to vary in time was applied to tide gauge records at select sites in the Pacific Islands. This approach enabled the extreme water level signal to be decomposed into its various components and be recombined in a way that more accurately reflects how the various components can combine to determine extreme water levels at a specific place and time. The results indicated that the relative importance of the various components differed from place to place and that in response to a changing climate, alterations to natural patterns of sea level variability and storminess (in addition to increasing global sea level) can contribute to the more frequent occurrence of extreme water level events. The results also revealed areas in which further work is needed; as a result, the focus of the current proposed work is to:

1. enhance the historical diagnosis of site-specific still water level (SWL) patterns and trends to more clearly decipher the differences in location and scale parameters and better isolate contributions of waves within tide gauge signals;
2. explore techniques that can be used to support regional analysis to address limitations in tide gauge records, in particular poor spatial coverage, including the use of satellite altimetry and other types of data;
3. extend significantly the historical diagnosis of and potential prognosis for extreme water level;
4. patterns and trends by applying it to the total water level (TWL; i.e., including the effects of waves) focusing on, but not limited to, the expression of ”lesser extremes” (e.g., annual to decadal event probabilities); and
5. address gaps that exist in the types of assets currently considered, as well as gaps in the measures used (such as damage/fragility curves) to evaluate impacts of coastal flooding in all its forms to assets on an individual basis and in aggregate under different climate change scenarios.

The results of proposed work will advance the practical applications of coastal flooding analysis, and they will lead to an improved understanding of which components of Department of Defense (DoD) facilities and infrastructure are potentially vulnerable to coastal flooding and how they could be affected, as well as how species and ecosystems associated with DoD lands and waters will respond in a changing climate. They will be amenable to incorporation into site and region-specific tools and models to inform decision and policy making. The results will have broad interest within the region and the nation.