Sea Level Rise Vulnerability Assessment and Capital Improvement Project Adaptation Plan
Publication Date
6-5-2025
Publisher
City Of Arcata GHD
Abstract
Previous studies along with local and global climate models have indicated that the shoreline and select lower elevation landward regions of the City of Arcata (City) are susceptible to increased inundation and flooding from sea level rise (SLR) and storm events. Within these vulnerable areas exist critical infrastructure including City utilities, transportation assets, and other public facilities that warrant study and adaptation planning. The California Coastal Commission’s Local Coastal Program (LCP) Local Assistance Grant Program has awarded the City funding to pursue the Arcata Sea Level Rise Vulnerability Assessment and Capital Improvement Project Adaptation Plan (Project). The City is currently revising their LCP with updates to the Local Coastal Element that reflect the most up to date understanding of the implications of projected SLR and precipitation. To better understand potential impacts of coastal, fluvial and groundwater flooding on City assets and inform the design and development of capital improvement program (CIP) projects, a vulnerability and risk assessment was completed. The assessment was conducted utilizing hydrodynamic modeling of current and future tidal water levels, precipitation events and groundwater levels to identify flood pathways, extent, depth and duration for a range of flooding scenarios. The vulnerability assessment addresses the questions: What City assets may be adversely affected by flooding and when? The risk assessment accounts for the likelihood that an asset will be impacted, the types of impacts, and the consequence of those impacts. The risk assessment is used to inform the temporal and spatial prioritization of adapting assets for future conditions. The framework for these assessments is presented in Figure ES-1. Adaptation strategies will be developed and presented in a subsequent report.