Highways in the River Environment - Floodplains, Extreme Events, Risk, and Resilience - FHWA Hydraulic Engineering Circular 17 (HEC-17)

The Federal Highway Administration (FHWA) manual Highways in the River Environment - Floodplains, Extreme Events, Risk, and Resilience provides technical guidance to assist transportation agencies in assessing vulnerabilities of assets and facilities to climate change and extreme events occurring in riverine environments. It includes new information on how to account for changing precipitation conditions including more frequent and extreme weather events that may affect transportation infrastructure and drainage systems in riverine environments, consisting of rivers and streams, lakes, wetlands, and other natural features conveying water. The manual does not address interactions between coastal and riverine environments, such as when coastal waters influence rivers and streams flowing into them. 

The manual includes an overview of how federal policies affect transportation in or near floodplain areas (including those of FHWA and FEMA), a description of flood events affecting transportation and statistical hydrologic models used by engineers, a discussion of key drivers of nonstationarity (particularly climate change and land use changes), with emphasis on climate modeling and techniques for projecting future flooding. Chapter 5 of the manual addresses the importance of climate modeling for estimating extreme flows of water in riverine environments, and discusses climate modeling, downscaling, emissions scenarios and resources available to help planners and engineers incorporate climate change into planning and design. Chapters 6 and 7 address the concepts of risk assessment and resilience, describing a framework for risk and resilience assessment in floodplain development and hydrologic design that can be tailored for specific projects. Finally, the manual includes case studies to illustrate the concepts and methods described throughout the manual.

The manual updates and supersedes the first edition of HEC-17, which was initially published in 1981. This update was developed to address a need for improved approaches to risk assessment and planning, design, and operation of transportation infrastructure in the context of both climate change and fiscal constraints. The manual is intended for use by agencies and individuals involved in roadway infrastructure design, such as hydrologists, hydrualic and civil engineers, and roadway designers.

Publication Date: June 2016

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