As one of its core research focuses, the U.S. Environmental Protection Agency’s (EPA’s) Homeland Security Research Program (HSRP) is interested in refining its tools and methodologies to better characterize the fate and transport of hazardous contaminants during all phases of an emergency response. Atmospheric dispersion modeling is one tool that can be used for effective emergency preparation or response from hazardous chemical, biological, radiological, nuclear, and explosive (CBRNe) releases, especially in urban areas where population densities are high and wind flow becomes altered between buildings and street canyons.
The goal of this report is to explain the fundamental concepts of atmospheric transport and dispersion and provide a comprehensive database of dispersion models that can be used for emergency preparation and response to facilitate discussion between public, private, academic, and/or government sectors. The abundance of available modeling options creates confusion and results in challenging decisions regarding the type of model to be used during different scenarios. A comprehensive dispersion model review of this magnitude has also not occurred recently. This report provides a literature review of previous model review efforts to lay the foundation for this updated database, provides introductory concepts on boundary layer meteorology and the types of dispersion models available (e.g. Gaussian Plume or Puff, Lagrangian, or CFD models), and outlines a comprehensive list of 96 dispersion models that could be considered for wide-area release risks. Sixteen of those models were selected for a more detailed two-page review due to their potential applicability and usefulness for emergency response. This model review is not meant to recommend or endorse a specific model, but to provide users with a resource of available modeling options. Even though no single model tends to have all the capabilities that are beneficial during the consequence management of a wide area release, this report is meant to identify the strengths and limitations so users can make informed decisions. This report covers a research period from September 2018 to June 2020 and work was completed as of July 2020 as part of the author’s Ph.D. dissertation.
This document first outlines the project background, justification, and goals in Section 2.0, along with a short literature review of previous dispersion model compilations. Section 3.0identifies the role of dispersion modeling in emergency preparation and response, details the available operational dispersion modeling resources, and defines EPA’s role in emergency response. Section 4.0 provides an overview of atmospheric turbulence and the fundamentals of dispersion within the Planetary Boundary Layer (PBL) and urban areas. The types and corresponding strengths and limitations for different dispersion models are covered in Section5.0. Section6.0describes the model review process, specific details included in the review, and the criteria used to determine inclusion or omission of the model in the detailed review. An extensive quick reference table for 96 different dispersion models is provided in Section7.0, and 16 of those models are selected for additional review in Section8.0 due to their applicability and usefulness for emergency response.