Resilience Infrastructure and Future Hazard Impacts: Tropical Cyclones

Summary

Observed changes in the climate system, including increases in land, atmospheric, and ocean temperatures and in the frequency and intensity of rainfall and tropical cyclones, are imposing additional stress on the built environment beyond the current design requirements and potentially putting lives at risk. Current building codes and standards do not yet consider the hazards associated with hurricanes - including wind speed, storm surge, and waves - as coupled and correlated events.  In ASCE 7-22, the coastal wind speeds and storm surge heights for structural design are prescribed independently.  In fact, these hurricane-induced hazards are coupled and are highly dependent upon the bathymetry and topography of the local area of interest (Phan et al., NIST TN 1482, 2007; Phan and Simiu, ICASP11, 2011; Phan et al., NISTIR 7689, 2010). In addition, there is currently no consideration of the hydrodynamic forces that are associated with storm surge flow velocity acting on coastal structures.  Further complicating the effort to characterize coastal hurricane-induced hazards for design criteria is the fact that hurricanes are evolving in duration, intensity, and frequency because of increased ocean and atmospheric temperatures.  This, coupled with increasing sea level rise (SLR), means current design criteria for the built environment in coastal regions need to be updated to address correlated coastal hazards to ensure building performance and community resilience.

Description

Credit: Image by WikiImages from Pixabay

Objective
By 2028, develop a methodology for quantifying hurricane-induced hazards, including wind speed, storm surge, waves, and associated hydrodynamic effects, with consideration of the near- and long-term effects of natural hazard evolution.

Technical Idea
This project will investigate and quantify the temporal effects of the evolution of natural hazards, including SLR, on the four components of storm surge (tidal stage, barometric tide, wind stress tide, and wave set-up), which can vary differently depending on the bathymetric and topographic conditions of the location of interest along the Atlantic and Gulf coasts.  Once this is determined, the project will perform mass hydrodynamic simulations using simulated hurricanes in the National Hurricane Center (NHC)’s HURDAT2 database and probabilistic treatment of simulation outputs to extract maximum wind speeds, maximum storm surge, and wave heights, and maximum flow velocity and to develop joint probabilities of these joint hazards for near- and long-term projections of future hazard events for any specific locations of interest in hurricane-prone regions.

Research Plan
The research plan consists of two concurrent activities.

First, this project supports the larger MSSD program that focuses on developing a roadmap to identify research needs and implementation activities to incorporate future hazard projections in the tropical cyclones, storm surge, and coastal flooding hazard areas, in codes, standards, and guides for the design or assessment of buildings and infrastructure systems and to support community resilience and functional recovery. The roadmap will be developed through a collaborative effort with subject matter experts as well as a stakeholder-driven process with federal and industry partners (e.g., FEMA, NOAA, ASCE, ICC, Canadian Building Code) through two phases of work:

Phase 1: A working group of subject matter experts (SMEs) with expertise in the characterization of natural hazards and engineering is working with NIST researchers on two NIST publications. The first publication will provide an overview of foundational documents and current practices, guidance on when and how to use downscaled environmental data for regional/local applications, associated increases in uncertainty, and an assessment of gaps and needs for using future hazard projections in codes, standards, and tools as well as community resilience planning.

Evolving natural hazards include flood (sea level rise; coastal and inland flooding), wind (hurricane and tornadoes), precipitation (rain, snow, hail), atmospheric temperatures, wildland-urban interface (WUI) fires, and earthquakes (landslides). The material focus includes performance and durability for adverse environmental effects, such as increased rates of corrosion. Structural and community focus includes structural capacity, the service life and reliability of existing structures, and functionality over time. This publication will serve as the basis for future planning and activities.

A contractor will assist with hosting a series of hybrid workshops to further inform the development of the second publication. The workshop will identify specific research needs and implementation activities required for each of the topical subjects identified in the first publication and through the workshops. The NIST team and SMEs will work with the contractor to develop the content for the workshop series. The workshops will identify experts in natural hazard evolution, vulnerability of infrastructure, and design adaptation to obtain broader perspectives on the focus areas and priorities identified in the first NIST publication. The information collected at the workshop will inform the second publication: a research roadmap with specific action items and research activities for various stakeholders who can play a role in implementing future hazard conditions in next-generation codes and standards.

Phase 2: After completing the roadmap, the NIST team will identify research topics for MSSD projects based on their priority and the availability of resources and expertise. Multiple research projects are expected to be launched within MSSD.

Second, this project will perform the following major tasks to quantify future hurricane-induced hazards for the Atlantic and Gulf Coast regions:

• Quantify the near- and long-term effects of hurricanes and sea level rise (SLR) on the Atlantic and Gulf coasts.
• Conduct hydrodynamic simulations using synthetic hurricanes from the Florida Public Hurricane Loss Model (FPHLM) and projected representative future hurricanes and Advanced Circulation Model (ADCIRC), coupled with storm surge and waves from Simulating Waves Nearshore (SWAN) model (Delf Technical University), for the Atlantic and Gulf coast regions with initial conditions of (1) no SLR, (2) near-term projection of SLR, and (3) long-term projection of SLR.
• Develop joint probability distributions for hurricane-induced hazards (wind speed, storm surge, waves, and flow velocity) in the Atlantic and Gulf coast regions for varying initial conditions based on SLR.

Based on the joint probability of hurricane hazards, compute the probability of the coupled hazards using the NIST methodology (see NIST TN 1482) to provide the technical basis for the determination of appropriate design criteria for the projected future coastal flooding hazards.