Columbia River Treaty 2014/2024: HEC-WAT and the FRA Compute Option

Abstract

The U.S. Army Corps of Engineers (USACE) has long had a policy stating that USACE will perform its water resources studies using risk analysis and watershed, systems, and life-cycle approaches. However, the software to support these requirements and perform these analyses has not been available. For this reason and others, USACE's Hydrologic Engineering Center (CEIWR-HEC) began developing the watershed analysis tool (HEC-WAT). HEC-WAT was initially developed to assist project delivery teams conduct water resources studies of complex riverine systems with an integrated, comprehensive, and systems-based approach. More recently, the capability to perform a life-cycle approach was added to HEC-WAT. To perform a life-cycle analysis, HEC-WAT added the flood risk analysis (FRA) compute option. This capability allows HEC-WAT to run a Monte Carlo analysis so a robust risk analysis can be performed throughout the life cycle. HEC-WAT/FRA now includes systems and life-cycle approaches, event-based sampling, parameter sampling, and the ability to do scenario and alternative analyses. Members of the Columbia River Treaty (CRT) 2014/2024 Review team heard about the HEC-WAT/FRA capabilities and decided the software met the needs of their study. Therefore, an implementation of HEC-WAT/FRA was constructed for the CRT project. This paper will describe HEC-WAT/FRA and how the software was used to assess current treaty operations and possible future treaty alternatives. This paper will also describe the scientific advancements included within HEC-WAT/FRA, how those advancements were used for the CRT study, and how HEC-WAT/ FRA will advance USACE modeling approaches for flood risk analysis.