Building Resilience to Challenges and Disruptions

With unprecedented investments in coastal community and ecosystem resilience, federal, state, tribal, and local entities are tasked with determining their vulnerability, identifying activities towards mitigating current and future risk, and prioritizing which actions to pursue. Coastal communities in particular are facing a combination of offshore, nearshore and inland extreme events playing out across a dynamic landscape of tidally influenced ecosystems. This highly coupled system requires innovative approaches to understanding how multiple possible actions will perform to both protect them from flooding and erosion and to attain other values like improving recreational opportunities, fisheries, or economic gains. 


NOAA's Competitive Research Program (CRP) has spent the past eight years supporting interdisciplinary teams across the country to advance the science and products needed by coastal managers. This includes work on present and future flood vulnerabilities and solutions to mitigate risk, while also considering impacts to built and natural infrastructure. Increasingly, there is a need for advanced ecosystem change modeling to inform the success of multiple short- and long-term on-the-ground projects with different levels of community support, across a region. 


This talk will emphasize a collaborative effort through the Cooperative Institute for Research to Operations in Hydrology to inform decision making at local and regional scales by advancing compound flooding and ecosystem change modeling. We will also highlight an ongoing collaboration to create a user-informed national framework for applying marsh models. Both case studies represent successful, multifaceted collaboration and offer insights for future efforts seeking to connect cutting-edge science to coastal communities.

The complexity of compound flooding, resulting from the interplay of rainfall, storm surges, and riverine flooding, calls for an advanced and integrated approach to flood risk assessment. This presentation details the end-user engagement that is foundational to an ongoing compound flood modeling project focused on better estimating flood dynamics and assessing the impacts of resilience strategies, particularly nature-based solutions (NBS), in Mobile Bay, Alabama. The overarching goal of this project is to enhance coastal resilience by providing actionable guidance for project implementation, policy development, and watershed management planning. A collaborative end-user engagement process is central to the project to infuse the science outputs into practical application.
The project team has held two face-to-face workshops with local coastal decision-makers. The first was designed to present the project's goals and objectives and characterize compound flooding as a group while also collecting input on stakeholder needs and planning priorities. Through facilitated discussions and activities, we gathered information on the types of outputs and products most beneficial for management and planning. The project team also gathered information about flood hotspots and areas that would be ideal locations to implement NBS. At the second workshop, the project team collected detailed feedback on the performance of preliminary compound flood models. Attendees were able to compare coastal-only and compound model results and provide feedback on the perceived accuracy. This feedback has provided critical insights into the model's performance and highlighted areas for model refinement. We will discuss how workshop feedback has been applied by the project team, highlighting how the lived experience of the end-user group has informed modeling efforts. 
This presentation is part of the Cooperative Institute for Research on Hydrology (CIROH) project titled "Assessing Nature-Based Solutions to Mitigate Flood Impacts and Enhance Resilience".

Coastal wetlands can mitigate the impacts of compound flooding from two or more co-occurring flood drivers (e.g., precipitation and storm surge), thereby promoting coastal resilience and climate readiness. As such, coastal wetlands can serve as nature-based solutions (NBS) to address compound flooding and enhance resilience. Successful NBS implementation requires scenario-based evaluations of changes in sea level, precipitation, and other aspects of the coastal landscape, as well as coordination among natural and social scientists, engineers, and local stakeholders. Our goal is to evaluate NBS designs for tidal wetlands in Mobile Bay, Alabama, using field-based measures of vegetation and coupled models. Using input from local stakeholders, we identified reference sites, target NBS sites, and existing NBS sites that differ in compound flooding impacts and dominant vegetation. We surveyed key biological inputs to ecological models, including the elevation ranges, maximum aboveground biomass, and rooting depths of dominant vegetation in winter and summer 2024. Surveyed marshes spanned a broad elevation gradient from -0.68–0.89 m (NAVD88), with optimal elevations varying by site and vegetation type. Maximum winter biomass varied among sites and dominant vegetation by an order of magnitude, and maximum rooting depth ranged from 25.8–46.1 cm, on average, across vegetation types. Collectively, these results suggest that biological variables differ within and among sites throughout Mobile Bay, which may have important implications for modeling efforts. Further, the ability of coastal wetlands to decrease flooding impacts may differ seasonally due to changes in plant biomass throughout the year. These data will inform modeling efforts designed to evaluate a range of climate, hydrological, and socioeconomic scenarios and the flood-reduction efficacy of proposed NBS in the region. This presentation is part of the Cooperative Institute for Research on Hydrology (CIROH) project titled "Assessing Nature-Based Solutions to Mitigate Flood Impacts and Enhance Resilience."

Mobile Bay, a major Gulf Coast estuarine system, faces frequent threats from compound flood events driven by a combination of storm surge, riverine discharge, and intense precipitation, often aggravated during hurricanes and extreme hydrometeorological events. To better understand and be prepared for these flood hazards, we employ physics-based numerical models to assess flood extent, depth and magnitude of associated currents during storm events. The modeling framework couples ADCIRC hydrodynamic model to simulate storm surge across the Gulf Coast-Mobile Bay area, and HEC-RAS 2D for detailed hydraulic routing of riverine discharge and precipitation within the deltaic-bay sector. We simulate the impacts of historical hurricanes (e.g. Sally, 2020) and synthetic hydrometeorological events, and assess the flooding hazard under various scenarios around the Bay. The results of this work highlight the areas within Mobile Bay prone to compound flooding and their associated impacts, providing crucial data on dangerous areas, that can inform decision-making and enhance resilience strategies. This research offers insights into potential future flood scenarios, emphasizing the importance of multi-faceted modeling approaches in capturing the complexity, and typically, non-linearities of compound flood events. Potential end-users are engaged throughout the entire project through workshops. They provide local knowledge to help modelers improve the modeling. End-users' feedback also helps modelers tailor the products of this project and translate the findings into actionable plans for community preparedness and adaptive management strategies, ultimately contributing to the region's overall resilience against future climate challenges. This presentation is part of the Cooperative Institute for Research on Hydrology (CIROH) project titled "Assessing Nature-Based Solutions to Mitigate Flood Impacts and Enhance Resilience".