Coastal Protection Under a Changing Climate

This workshop is particularly for those living and/or working in Coastal areas who are striving to better assess vulnerabilities and adapt to anticipated climate driven changes and sea level rise. Designed for inter-disciplinary learners of all levels, this presentation will use the seismic and hydrologic backdrop of Humboldt Bay’s sand dunes, baylands, aglands, and urban centers to provide an overview of localized assessment and adaption to sea level rise and climate change. A selection of both time-tested and emerging restorative management interventions, including hard-engineered protection, living shorelines, and enhanced natural buffers will be presented.

Full Abstract: Due to seismic deflection and subsidence, parts of California’s north coast are both increasingly desirable to develop and increasingly vulnerable to climate driven changes in storm patterns, wind, fog, sea level rise, and natural disasters such as tsunamis. Coastal communities are on the frontline of global climatic changes and are under increasing pressure to assess their vulnerability and develop adaptive strategies to current and anticipated changes. This session provides an overview of how communities around Humboldt Bay in Northern California are evaluating their future and prioritizing a combination of adaption strategies ranging from fortification to retreat and including measures inclusive of building or improving upon hard-engineered structures, developing living shorelines, and enhancing natural buffers, to name a few.

More specifically, this course will provide a methodology for assessing local sea level rise from a combination of eustatic sea level rise (SLR), tide gages, land leveling, and analysis of geologic uplift and subsidence. Once local SLR trajectories are determined relative to land level, an assessment of community vulnerabilities is conducted. Adaptions are then developed to mitigate vulnerabilities.

While dikes, sea walls and other traditional infrastructural elements are considered, they are not in themselves a sufficient solution. Even with fortification, higher tides can inhibit upland stormwater drainage without a network of pump stations. Higher sea levels can also cause groundwater to rise on the inboard side of fortifications reducing permeability converting near shore grasslands to wetlands. Moreover, higher tides can hasten saltwater intrusion. Hence, fortification and adaption strategies are more complex to plan. This session will explain several policy level approaches including conversion of landuse designations and phased partial retreat. The heart of the session will focus on nature based solutions including enhancement of natural dunes, salt marshes, estuaries, as well as conservation lands, agricultural fields, and other areas in which volumetric capacity of water bodies can be increased to attenuate higher tides. Living shorelines that offer buffer and transitional habitats can also be part of the adaption strategy.

In this session we will also discuss the inter-jurisdictional nature of the coastal zone and the challenges to bring planning entities and stakeholders together to discuss the slow moving flood of sea level rise. The instructor will be querying participants to share other unique approaches.