A Compound Flooding Manual of Practice for Engineers

Abstract Submission: Compound flood events result from a combination of multiple meteorological, hydrologic and oceanographic drivers occurring either in close succession or concurrently. These events often lead to greater impacts on flood magnitude, volume and duration compared to events driven by individual factors. Key contributing drivers include heavy precipitation, storm surges, waves and tides, river floods, and high groundwater levels. These drivers may be statistically interdependent, and the processes that cause them may be non-stationary. The rate and magnitude of the changes of these processes are subject to significant uncertainty due to a lack of understanding of model physics and the natural variability in the climate system. Traditional engineering practices have generally used univariate approaches that assume stationary conditions. To address the challenge of compound flood analysis in a changing climate, the ASCE Committee on Adaptation to a Changing Climate is writing a Manual of Practice (MoP) on Compound Flooding. The purpose of this MoP is to provide guidelines for the practicing engineer on how to analyze compound flooding events. The MoP provides definitions and typologies of compound flooding and their characterization in statistical and process-based frameworks. It describes hydrodynamic process-based models, including rainfall-runoff, riverine, and coastal models, statistical models of compound flooding, including measures of correlation, multivariate statistical methods particularly the use of copulas, and non-stationary analysis, the joint probability method which is a probabilistic modeling framework for estimating the frequency of exceedance of coastal hazards, and hybrid models which link statistical and process-based models. The MoP reviews how the conditions affecting compound flooding are changing and methods for analyzing projections of future compound floods. Risk and uncertainty analysis is presented describing methods for incorporating uncertainty in engineering planning, design, and risk assessment. The MoP includes case studies to illustrate how the models and methods can be applied to practical problems.

Learning Objectives/Expected Outcome (Optional) : An overview of the Manual of Practice on Compound Flooding