Project period: 6 17 24-6 16 26PROJECT title: compound flood hazards and climate adaptation in the pacific northwestaward purpose: coastal communities, especially those along estuarine coastlines,…

This Cooperative Agreement award from the U.S. Geological Survey (USGS), under the USGS Research and Data Collection program (CFDA 15.808), provides $239,278 to the University of Washington to conduct research focused on three main topics:

1. Modeling flood hazards in river delta systems, with a focus on the Nooksack River and understanding the impacts of morphological changes on flooding under future sea level rise scenarios.

2. Developing a conceptual framework for modeling compound flood hazards in the Pacific Northwest, considering a range of hydrodynamic drivers as well as co-seismic subsidence and other morphological changes.

3. Investigating the influence of adaptation or hazard mitigation strategies, such as green, grey, or nature-based solutions, on hydrodynamics and flood hazards along the Puget Sound and outer Pacific Northwest coasts.

The anticipated deliverables include peer-reviewed publications, conference presentations, and methods to advance the USGS Coastal Storm Modeling System (COSMOS), specifically for the Pacific Northwest region. The primary beneficiaries are agencies and communities along the Pacific Northwest coasts, as well as the broader scientific and practitioner communities engaged in coastal hazard prediction and mitigation.

Activities

Research conducted during this project will address three mainresearch topics: 1) river delta flood hazards modeling: this work will focus on modelingmorphological change in fluvial and estuarine systems to understand the impacts on flooding. Wewill continue the development of a two-dimensional hydro-morphodynamic model of thenooksack river, focusing on the causes and consequences of the november 2021 flood event.as part of this project, we will extend the sediment transport and morphodynamic modelingdownstream into the tidal reaches in order to understand the linkages between these processesand flooding under future sea level rise scenarios. 2) pacific northwest compound flood hazardsmodeling: compound flood events can be generated by combinations of a wide array ofhydrodynamic drivers, such as high discharge events from precipitation or snow melt, stormsurge, and tides. In addition to these hydrodynamic drivers, prediction of future compound floodhazards must consider risk of CO-seismic subsidence and other morphological changes, such assediment infilling or shoal migration. This work will build out a conceptual framework forincorporating these drivers into hazard models such as cosmos. 3) climate adaptationmodeling: this work will investigate the influence of adaptation or hazard mitigation strategiessuch as green (e.g., tidal marsh restoration), grey (e.g., sea walls), or nature-based (e.g., dynamicrevetments) solutions on hydrodynamics and therefore flood hazards along puget sound andouter pacific northwest coasts. We will use hydrodynamic modeling to assess the efficacy andimpact of potential solutions.deliverables and expected outcomes: anticipated deliverables include peer-reviewed data andpublications, conference presentations, and methods developed to advance cosmos, specificallyfor the pacific northwest puget sound and outer coast shorelines.

Intended beneficiaries

The primary beneficiaries of this project are agencies and communitiesalong pacific northwest coasts, and more broadly the scientific and practitioner communitiesengaged in coastal hazard prediction and mitigation.