Streaming Media
Presentation Abstract
Future changes in the Pacific Northwest climate have implications for regional habitat restoration, flood hazard mitigation and community resilience. Modeling regional exposure to flooding requires capturing the interactions of extreme stream discharge, sea levels, and flood mitigation controls (e.g., dams, flood gates). Here, extreme statistics of stream flow are derived from ensemble hydroclimate forecasts throughout Puget Sound, provided by the Columbia River Climate Change study (CRCC, Chegwidden et al., 2017). Flow projections are examined from four hydrologic models (three Variable Infiltration Capacity models and one Precipitation Runoff Modeling System model) used in the CRCC, each forced by 10 different global climate models for Representative Concentration Pathways (RCP) 4.5 and 8.5. Computed changes in extreme flow statistics for the 2040s and 2080s relative to historic values are used to adjust observed hydrographs from two different flood types (10¬–yr and 25–yr recurrence flows) on the Nooksack River and modeled with a Delft 3D Flexible Mesh compound flood model. The hydrodynamic model employs a 1D grid network in the Nooksack River connected to a 2D floodplain and delta/tide model, allowing for high model resolution with relatively low computational cost (compared to traditional 2D implementations). Moreover, water levels are simulated with the combined influence of new probabilistic sea level rise estimates for Washington State (Miller et al., 2018). Model results show that flooding extent will increase with higher sea levels and increasing peak stream flows. Also explored are the relative contribution of each forcing through time. Simulated adaptive management alternatives show that floodplain habitat restoration can reduce flood exposure to agriculture, transportation, and critical habitat. Simulations of flood exposure on the Nooksack River under future conditions provide regional context and a blueprint for further assessment across Puget Sound.
Session Title
Poster Session 1: Applied Research & Climate Change
Conference Track
SSE14: Posters
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-posters-480
Start Date
26-4-2022 4:00 PM
End Date
26-4-2022 4:30 PM
Type of Presentation
Poster
Genre/Form
conference proceedings; presentations (communicative events); posters
Subjects – Topical (LCSH)
Floods--Washington (State)--Nooksack River; Floods--Washington (State)--Whatcom County; Floods--Northwest, Pacific; Climatic changes--Northwest, Pacific; Hydrometeorology--Northwest, Pacific
Geographic Coverage
Nooksack River (Wash.); Bellingham (Wash.); Whatcom County (Wash.); Northwest, Pacific
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Format
application/pdf
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons
Projected changes to the hydroclimate in the Pacific Northwest and implications for coastal hazards and compound flooding
Future changes in the Pacific Northwest climate have implications for regional habitat restoration, flood hazard mitigation and community resilience. Modeling regional exposure to flooding requires capturing the interactions of extreme stream discharge, sea levels, and flood mitigation controls (e.g., dams, flood gates). Here, extreme statistics of stream flow are derived from ensemble hydroclimate forecasts throughout Puget Sound, provided by the Columbia River Climate Change study (CRCC, Chegwidden et al., 2017). Flow projections are examined from four hydrologic models (three Variable Infiltration Capacity models and one Precipitation Runoff Modeling System model) used in the CRCC, each forced by 10 different global climate models for Representative Concentration Pathways (RCP) 4.5 and 8.5. Computed changes in extreme flow statistics for the 2040s and 2080s relative to historic values are used to adjust observed hydrographs from two different flood types (10¬–yr and 25–yr recurrence flows) on the Nooksack River and modeled with a Delft 3D Flexible Mesh compound flood model. The hydrodynamic model employs a 1D grid network in the Nooksack River connected to a 2D floodplain and delta/tide model, allowing for high model resolution with relatively low computational cost (compared to traditional 2D implementations). Moreover, water levels are simulated with the combined influence of new probabilistic sea level rise estimates for Washington State (Miller et al., 2018). Model results show that flooding extent will increase with higher sea levels and increasing peak stream flows. Also explored are the relative contribution of each forcing through time. Simulated adaptive management alternatives show that floodplain habitat restoration can reduce flood exposure to agriculture, transportation, and critical habitat. Simulations of flood exposure on the Nooksack River under future conditions provide regional context and a blueprint for further assessment across Puget Sound.
