USGS Coastal and Marine Scientists Prepare for an Active 2020 Hurricane Season
This article is part of the April-May 2020 issue of the Sound Waves newsletter.
Hurricanes and tropical storms unleash high winds, storm surge, coastal erosion, and inland flooding. These forces can destroy homes and businesses, affect future tourism and recreation, alter habitats, and profoundly change coastal and marine landscapes. Understanding how storms influenced coastal change in the past, monitoring coastal change during storms, and forecasting how the coast will respond to future storms of varying intensities can help mitigate coastal change hazards and their impacts. The comprehensive scientific information, data, and tools produced by the USGS Coastal and Marine Science Centers in Woods Hole, Massachusetts; St. Petersburg, Florida; and Santa Cruz, California can be used by decision makers, emergency planners, and communities to protect lives and property across the United States.
Research conducted by the USGS is critical in the face of the above-average Atlantic hurricane season forecasted for 2020 by our partners at the National Oceanic and Atmospheric Administration (NOAA). In fact, Supplemental Appropriations activities are being used to prepare for the 2020 Hurricane season in Puerto Rico and the Southeastern United States. Here, we highlight various USGS resources, tools, and research to help you better prepare for your local 2020 hurricane season (Western Pacific: May 15-November 30, Atlantic: June 1-November 30, and Central Pacific: June 1-November 30).
Forecasts and Simulations
USGS scientists use models to forecast how hurricanes reshape the coastline. Forecasts are used by decision makers, emergency planners, and communities to help them prepare for hurricanes and determine areas most vulnerable to risk.
The Coastal Change Hazards portal is an interactive tool that allows users to explore the probability of coastal erosion on sandy beaches along the U.S. Gulf and Atlantic coasts during hurricane conditions. The model uses observations of beach characteristics combined with models for surge and waves to estimate where sand dunes are likely to be eroded or overtopped by storm waves and where coastal areas behind the dunes could be inundated by seawater. Forecasts are used to make real-time decisions by emergency managers on evacuations, evacuation routes, and staging of heavy equipment for post-storm clean-up. Coast change forecasts begin 48 hours before a storm is expected to make landfall and are updated as new surge and wave models are released by the National Hurricane Center. The portal also allows users to see predictions for extreme water levels, shoreline change, and vulnerability to sea-level rise, and can be used for hurricane preparation in coastal zones.
The Total Water Level viewer and Coastal Change Hazards viewer allow coastal managers and others to see the elevation where the ocean will meet the coast during both normal and storm conditions. The tool displays real-time total water level forecasts and coastal change predictions for select regions of the U.S. coastline using local beach characteristics. Total water level at the shoreline is the combination of tides, surge, and wave runup. These forecasts can provide guidance on potential coastal erosion and flooding hazards. USGS and NOAA partner to provide operational total water level forecasts for all U.S. sandy open-ocean coastlines. The USGS Coastal Change Hazards program and NOAA National Centers for Environmental Prediction and the National Hurricane Center use sensors deployed by the USGS Water Mission Area to validate surge and wave-induced water level forecasts.
The Coupled Ocean-Atmosphere-Waves-Sediment Transport (COAWST) Modeling System is a research tool necessary to investigate the complex dynamics of coastal storm impacts. COAWST links earth-system components including the atmosphere, ocean circulation, waves, and transport of sand and mud providing enhanced capabilities to allow feedback between components. For example, a typical hurricane modeling simulation may include great details for the atmosphere component, but with limited connectivity to the ocean and sediment movement. With the COAWST system, these simulations will allow the ocean, waves, and sediment transport routines to dynamically evolve and provide feedback to the atmosphere simulation. This will modify the storm development and provide a more realistic suite of physical storm processes. COAWST has been applied to several targeted areas, including Fire Island, New York, for Hurricane Sandy (2012); Matanzas Inlet in Florida for Hurricane Matthew (2016); and North Carolina for Hurricane Florence (2018).
The Coastal Storm Modeling System (CoSMoS) makes detailed projections of storm-induced coastal flooding, erosion, and cliff failures over large geographic scales. CoSMoS models all the relevant physics of a coastal storm (e.g., tides, waves, and storm surge), which are then scaled down to local flood projections for use in community-level coastal planning and decision-making. Rather than relying on historic storm records, CoSMoS uses wind and pressure from global climate models to project coastal storms under changing climatic conditions during the 21st century. CoSMoS was developed for hindcast studies, real-time applications, and future climate scenarios to provide emergency responders and coastal planners with critical storm-hazard information that can be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources within complex coastal settings.
Before and After Storm Imagery
Coastal geologists quantify the amount of change that occurred, how the shape of the coast was altered, and the presence of new or altered shoreline features such as breaches in barrier islands using images collected before and after major storms. Knowing how the coast responds to storms can help inform emergency managers on areas to evacuate or to designate resources for post-storm recovery. Researchers use aerial imagery to quickly verify coastal change forecasts and provide actionable information to coastal planners and managers for informing decisions on response to future storms. With the Aerial Photography Viewer, users can view specific baseline or storm mission activities and their related before-storm imagery.
Monitoring and Measuring Coastal Change
Measuring coastal change is essential for calculating trends in erosion, evaluating processes that shape coastal landscapes, and estimating how the coast will respond to future storms, including hurricanes and sea-level rise.
Scientists use remote-sensing technologies, such as aerial photography, satellite imagery, lidar (laser-based surveying), structure-from-motion techniques, and orthomosaic imagery (birds-eye view), to analyze changes in coastal morphology across large spatial scales. Using remote sensing, USGS is able to analyze coastal change, including spatial differences in storm impacts, magnitudes of erosion, changes in vegetation cover, and habitat availability. As an example, models created for the Southeastern United States that are based on lidar-derived dune and beach features provide the most up-to-date probabilities of coastal erosion and inundation for hurricanes that threaten U.S. coastlines this season. Federal agencies, such as USGS, NOAA, and the National Park Service, as well as local officials and emergency management offices, use this information as guidance to inform pre- and post-storm decisions related to safety and property damage.
Scientists have installed cameras along some U.S. beaches to monitor coastal changes during storm events. For example, cameras have been operating at Madeira Beach and Sand Key, Florida, since January 2017 and June 2018, respectively. The use of video cameras to monitor ever-changing coastal conditions augments in-water instruments, which can be time consuming and do not provide observations at all times and at all locations. Images and videos are used to observe real-time coastal conditions and for comparing how conditions along the coast change through time. This includes, for example, tracking high water levels during a storm and monitoring the potential impacts of waves colliding with protective sand dunes.
Additional video cameras are installed at Unalakleet, Alaska, Dream Inn hotel in Santa Cruz, California, Sunset State Beach in Santa Cruz, California, and Head of the Meadow Beach, Massachusetts as part of the Remote Sensing Coastal Change project. Scientists designed a similar camera station in Tres Palmas in Rincón, Puerto Rico to better understand how waves propagate across coral reefs and cause coastal flooding along tropical shorelines during storms like Hurricane Dorian. This knowledge will help support planning for Puerto Rico's recovery from Hurricanes Irma and Maria.
USGS researchers analyze video collected from these cameras to estimate not only the total water level, but also current speeds, water depth, and beach elevation. These data improve computer simulations of coastal flooding and shoreline change that communities can use to plan for sea-level rise, changing storm patterns, and other threats to beaches.
The “During Nearshore Event Experiment,” or DUNEX, is a collaborative project investigating the way strong storms impact our coastlines. USGS conducts research on the subjects of coastal change and storm impacts as part of its mission, and USGS is one of many contributors to DUNEX. During this experiment, teams of scientists deploy equipment along beaches in the path of storms to measure how sand moves, how high-water levels rise, and what direction the sand and water move before, during, and after a storm. This information helps scientists understand exactly what happens during a storm and how we can be better prepared for extreme coastal changes on broad and local scales. Hilary Stockdon, Science Advisor for Coastal Change Hazards within the USGS Coastal and Marine Hazards and Resources Program says, “What is important about this, for USGS, is that we are doing research to improve the methodology for and accuracy of our forecasts.”
USGS dedicates a tremendous amount of time and resources to investigate storm-specific impacts. Studying these events helps validate and improve models to more accurately forecast future storm impacts. For example, Hurricane Dorian impacted a large portion of the U.S. Southeast coast, from Florida to North Carolina in September 2019. For this storm and many others, USGS forecasted potential coastal change and monitored changes in the shoreline along the affected coastline. Storm surge reached 0.5 to 1.5 meters above predicted tides, offshore wave heights in excess of 7 meters were observed near Cape Canaveral, Florida, and wave heights in excess of 8 meters were observed near Cape Hatteras, North Carolina. These large waves contributed an additional 1-3 meters of wave runup at the shoreline. The combined effects of surge and storm-induced wave runup created elevated total water levels at the shoreline, causing extensive erosion of the beach and dunes.
Our oceanographers also analyze ecosystem impacts from storms. A team of USGS researchers studied how Hurricane Irma impacted coral reefs in Florida and Puerto Rico. Damage to coral reef environments can lead to increased coastal hazards in the form of additional flooding and socioeconomic damages. Studying storm-induced reef degradation helps inform restoration strategies that mitigate these impacts. Early results show that storm damage to the reefs off Florida, Puerto Rico, and the U.S. Virgin Islands increased coastal flooding hazards, and that coral reef restoration could reduce those hazards. These data may influence post-storm restoration strategies by the Federal Emergency Management Agency (FEMA) and U.S. Army Corps of Engineers following the 2020 hurricane season.
Hurricane Sandy resulted in a variety of impacts along the highly populated northeastern Atlantic seaboard in October 2012. USGS conducted more than 25 projects designed to improve forecasts of impacts and ecological consequences. Ecological research following this major storm revealed an increase in nesting habitat for the piping plover, a threatened species. This research highlighted the importance of balancing ecosystem needs with human needs when protecting against storms. Improved understanding of storm impacts will better prepare us for the next one.
You can explore additional examples of storm-specific research efforts in the links below:
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