Research Technical Report

Evaluation of Erosion Mitigation Alternatives for Southern Monterey Bay

ESA PWA (May 2012)

Report prepared for Monterey Bay Sanctuary Froundation and the Southern Monterey Bay Coastal Erosion Working Group, 30 May 2012, ESA PWA REF.#1972.00. 216pp.

PURPOSE AND OBJECTIVES

The goal of this Evaluation of Erosion Mitigation Alternatives for Southern Monterey Bay (Alternatives Study) is to provide an assessment of various erosion mitigation measures to support development of a regional strategy to address coastal hazards in southern Monterey Bay. The purpose of the project is to provide a technical evaluation of various erosion mitigation measures, conduct a cost benefit analysis of some of the more promising measures and to make recommendations on Subregional approaches for effectively addressing coastal erosion in Southern Monterey Bay (SMB). Each of these measures was identified by the Southern Monterey Bay Coastal Erosion Workgroup (SMBCEW; See 1.2.1). In this study, each of the erosion mitigation measures were evaluated using a variety of criteria and compared with more traditional types of shore protection via a cost benefit analysis. A series of project alternatives were then developed. Each Alternative was comprised of one or more mitigation measures for each critical erosion Subregion that will avoid erosion hazards, protect upland development, and maintain beach health. This analysis therefore supports development of one or more shore management strategies for southern Monterey Bay, potentially as part of a Regional Shoreline Management Plan. The terminology is summarized in Section 1.1.3 Definitions. While focused on southern Monterey Bay, this report is expected to clarify the benefits, costs, and effectiveness of a range of erosion mitigation management measures for California's shores over multiple time horizons. Specifically, this report assesses the effectiveness of each measure at protecting upland property and beach widths, and compares the costs and benefits of each measure with coastal armoring, the status quo strategy for mitigating erosion impacts. This report is also expected to begin to inform adaptation to increased coastal hazards and vulnerability resulting from accelerated sea level rise.