Proposal title: evaluating longevity and non-local benefits of coastal nature-based solutions using data-driven modeling natural and nature-based features (nnbf) are increasingly sought to reduce…

Proposal title: evaluating longevity and non-local benefits of coastal nature-based solutions using data-driven modeling natural and nature-based features (nnbf) are increasingly sought to reduce coastal flooding and storm impacts, yet the capability to evaluate the performance and lifespan of nnbf remains an ongoing challenge for california and the united states. Coastal decision-makers and engineers lack capable modeling tools and data to evaluate potential benefits and trade-offs of nnbf, especially when considering how nnbf might evolve and degrade over time. This omission impedes understanding the true nature of long-term SLR impacts. Further, benefits of nnbf are typically quantified in terms of avoided flood damages to local coastal properties, which can inadvertently prioritize protection for higher income areas. Non-local benefitssuch as beach visitation are rarely accounted for in cost-benefit assessments. This project will adapt, make available, and provide use-case tutorials and training for coastal change modeling and use commercially available cell phone location data tools to evaluate the longevity and CO-benefits of nnbf projects. Coastal change modeling builds on the existing U.S. Geological surveys coastal storm modeling system [cosmos] framework, one of few hazard modeling systems that captures feedback between coastal erosion and flooding. The shoreline-change model (cosmos-coast), which has been pre-calibrated using data assimilation of extensive satellite-derived shoreline observations across california, will be adapted to simulate CO-evolution of the beach, natural and managed dunes, and flooding. This will provide an estimate of the local coastal flood-protection benefits associated with nnbf projects, and combined with cell-phone based visitation data to gauge against non-local benefits (e.g., impact of beach width on beach access) to enable a more accurate method of evaluating nnbf and their CO-benefits. We will leverage four existing planned nnbf project sites in north-central california and develop use-case tutorials targeted to coastal managers, engineers, and consultants across california who will be able to readily access and adapt the tools to evaluate nnbf design alternatives and answer questions such as: how much sand? Where should IT be placed? How often? What are the local flood-protection and non-local CO-benefits of this nnbf project? The refinement and publication of existing models, techniques, and case-study examples proposed here will enable rapid evaluation of a wide range of design alternatives that will enable local coastal managers to more accurately weigh the CO-benefits of nnbf to help determine where to focus long-term efforts and ultimately foster innovation and efficiency in the advancement of nnbf statewide.