Morphos: Advancing Coastal Process Research and Modeling
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MORPHOS: ADVANCING COASTAL PROCESS RESEARCH AND MODELING Jeff Hanson US Army Corps of Engineers, Field Research Facility, Duck, NC Email: [email protected] Don Resio, Jane Smith and Rob Wallace US Army Corps of Engineers, Coastal and Hydraulics Lab, Vicksburg, MS 1. Introduction The 2004-2005 Hurricane seasons resulted in more than 30 billion dollars in US property loss and damages and nearly 2000 direct fatalities within our coastal communities1. This devastation painfully demonstrates that our national coastlines are not adequately protected against recurring extreme weather events, and that there is a significant risk of sustaining high damages and losses from future events. This risk is exacerbated by many factors, including coastal development pressure, increased storm activity, sea level rise, coastal subsidence, and loss of wetlands; and the potential societal and economic consequences of decisions in the area are enormous. Furthermore, the current level of risk cannot be well quantified using existing models, as these major catastrophes transcend our past experiences and exhibit impacts that fall outside the range of model tuning for existing tools (Riley 2007). Some of the key issues that currently appear to be beyond the state of the art in coastal predictions include wave-current-vegetation interactions (critical to determining the value of wetlands and wetland restoration in coastal areas), estimates of low-volume levee overtopping rates over natural surfaces (critical to levee design), accurate objective specification of bottom friction (critical to surge level prediction and evaluating wetland impacts), accurate estimation of wave-driven radiation stresses in coupled wave-surge models (present models appear to underpredict this surge component), potential baroclinic and 3-D effects in surge predictions (how important is this?), wind field specification in coastal areas (this drives the entire system and presently “neglects” coastal effects), quantitative understanding of the effects of climate variability on expected future extremes (even more critical when sea level rise is also considered), quantitative prediction of coastal response during extreme events and during recovery following these events (can beaches/dunes provide effective protection in extreme events?), statistical characterization of meteorological events that produce coastal hazards (sample size is very small!), and system-wide risk estimation methodologies (typically not performed by people who understand specific coastal problems). This is certainly not an exhaustive list; however, it points out that research needs are very broad and cannot be “pigeon-holed” into a single small niche. 1 National Hurricane Center Archives, http://nhc.noaa.gov. 1 A logical question that arises from the previous list of deficiencies is how did we end up with shortfalls in so many key technologies? Probably a large factor contributing to this fact is that most existing modeling systems focus on operational systems and incorporate many empirical factors that can be used to fit local situations. For example, coefficients and even physical systems are changed from site to site in applications. These are typically “tweaked” to provide a reasonable approximation to available measurements and little information is gained, since variations in coefficients and different sets of “physics” allow for very large variations in the results. In short, present systems appear to focus on developing effective empirical tuning methods for optimizing performance. Whereas this approach works relatively well for operational systems, it is not expected to work well in most of the shortfall areas mentioned above. As a result of the deficiencies noted above and the current approach in modeling systems, there is a critical need within the coastal engineering community for a reliable, physics- based modeling capability for tropical and extra-tropical storm risk assessment. Such a capability needs to incorporate improved objective estimates of winds, waves, currents and water levels, and coastal response (erosion, breaching, and accretion) during extreme events, without having to adjust several coefficients to produce realistic results. Furthermore there is a need for a robust, standardized approach to establishing the risk of coastal communities to future occurrences. Such a system of tools could be used to plan and prepare for weather impacts on our fragile coastal communities and resources. The Morphos program was established by the US Army Corps of Engineers (USACE) to address these needs. The program was initially funded with emergency appropriations stemming from the destructive 2004 hurricane season, which brought Hurricanes Charlie, Francis, Jeanne and Ivan to the Florida coastlines (Figure 1). Morphos was charged with developing a prototype integrated modeling system for predicting three-dimensional beach morphology changes during hurricane events. To address this charge, USACE assembled an international team of coastal process experts spanning government agencies, academia and private industry. The 2005 hurricane season brought new challenges with Hurricanes Katrina and Rita, resulting in barrier island obliteration, extensive wetlands destruction, levee failure and overtopping, and widespread flooding due to inundation (Figure 2). This total devastation prompted a realignment of the Morphos objectives to address coastal risk in all types of environments. In fact, many of the Morphos investigators shared duel roles on the Hurricane Katrina Interagency Performance Evaluation Task Force (IPET) and are involved with the Louisiana Coastal Protection and Restoration (LACPR) Program and the Mississippi Coastal Improvement Program (MSCIP). In 2007 Morphos became an established component of the System- Wide Water Resources Program (SWWRP). The mission of SWWRP is to assemble and integrate the diverse components of water resources management, providing users access to current and improved technologies for multidisciplinary system-wide assessments2. The goals of Morphos are consistent with the mission of several federal agencies, including the National Oceanic and Atmospheric Administration (NOAA), the Federal Emergency Management Agency (FEMA), the US Geological Survey (USGS), and the 2 https://swwrp.usace.army.mil/_swwrp/swwrp/4-pubs/FactSheets/SWWRPfactsheet.pdf 2 US Department of Homeland Security (DHS). Partnerships are being established with these organizations on various levels to ensure Morphos will fully meet the national need for an integrated modeling system capable of accessing coastal risk and designing an adequate level of coastal protection. Throughout this work USACE maintains a firm commitment to advancing both model physics and numerical methods in order to field the best possible technology. Figure 1. Beach front erosion on Hutchinson Island, FL resulting from 2004 Hurricanes Jeanne and Francis. Figure 2. New Orleans flooding after 2005 Hurricane Katrina. 3 2. Morphos Approach Morphos seeks to develop a state-of-the-art modeling system with a variety of tools to address our essential coastal engineering applications. Key program elements include a dedicated community steering group, research and development to advance the state of coastal process modeling technology, rigorous test and evaluation of individual model elements and systems, and development of a community set of tools (Figure 3). Community Steering Modeling Technology R&D • Climate/Risk Test and Evaluation • Meteorology • Critical Data Sets • Waves • Test Bed • Circulation/Surge • Sediment Community System • Risk Assessment • Project Design • Event Reconstruction Figure 3. Morphos program elements. It is vitally important that Morphos development be driven by community needs. These needs are communicated through a dedicated steering group of coastal engineers with representatives from both private industry and Federal Government. The steering group provides program oversight and direction for all phases of product development. Regularly obtaining such community inputs ensures that Morphos developments keep pace with requirements for estimating risk along our evolving coastlines. Morphos investigators conduct the necessary research and development to advance our physical understanding of important coastal processes and represent them with sufficient accuracy in efficient numerical algorithms. This work can take many forms, including analyzing essential data sets, advancing new and existing theoretical descriptions of coastal behavior, and developing efficient computer applications for engineering use. This aggressive research and development component allows Morphos to continually embrace the latest technology and ensure that Morphos technology obtains, and holds, community acceptance as “state-of-the-art.” 4 A careful assessment of model performance against known standards and real-world scenarios is crucial for the success of Morphos. This need is being fulfilled through an aggressive test and evaluation program component. Elements of this effort include the collection and assimilation of essential data sets, development of a robust statistical package for quantifying model performance, and construction of a model test bed environment to provide Morphos developers convenient access to validation data and model assessment tools. A primary vision of Morphos is to develop a community system of modeling tools to address modern coastal engineering problems. Specific applications include risk