This Grant for Rapid Response Research (RAPID) will employ modeling and simulation based research which, if successful, will assist in a more effective emergency response to the Horizon oil spill catastrophe. In particular, the proposal complements satellite imagery and in situ observational tracking with 3-D computational modeling and simulation in order to accurately predict the movement of the oil plume associated with the very recent, massive and continuing Deepwater Horizon oil spill. To date, both movement and quantity of the oil has been largely unpredictable hampering optimal use of available resources to contain, mitigate and clean up the oil. Given the current 200,000-2,000,000 gallon/day estimate, the longevity of the oil in seawater will require a sustained response.
There are five research topics which will be pursued incrementally over the next twelve months: linking existing high resolution coastal circulation and wave models with an unstructured grid particle model (representing the spill movement); moving the linked models from 2D to 3D; refining the model based on real time observational data; optimizing the model to allow graphic output concurrent with model runs; introducing hurricane implications into the combined coastal model. Each individual topic as it is implemented, will improve predictability of the oil movement as it approaches shoreline.
In addition to the direct benefit of damage mitigation with improved oil tracking and prediction, the research from this award will have sustained value. The new simulation capabilities will be incorporated into existing coastal models, particularly those of the Gulf of Mexico, potentially giving benefit to any future emergency involving shoreline ecosystems.
Following the destruction of the Deepwater Horizon drilling platform in April 2010, the oil spill from the Macondo well posed a serious environmental threat to the northern Gulf of Mexico. Oil threatened immediately the fishing waters and marshes from Louisiana to Florida, and there was concern that oil would be carried on the Loop Current to more distant regions. Another looming concern was the potential that a major storm could impact the region during the spill. A land-falling hurricane in the Gulf of Mexico could have mixed the oil through the water column and pushed it farther inland, causing widespread environmental damage. Some portion of this oil could have settled to the sea floor after the storm, leaving oil within the low-lying marshes and bayous of the region. Ultimately the 2010 Atlantic hurricane season was relatively uneventful in the Gulf of Mexico, with only Hurricane Alex moving through the southern Gulf while the spill was active. Emergency management officials remained concerned about the possibility of a large storm and its interaction with the oil spill throughout the summer of 2010. Intellectual Merit: The focus of this NSF project was to develop a predictive computer model of oil movement in the Gulf of Mexico, and to apply this model to develop forecasts of the extent of the oil spill, especially in the nearshore. This work was initiated using the ADCIRC circulation model, which is driven by meteorological, riverine and tidal forcing and has been extensively used to predict waves and storm surge during land-falling hurricanes in southern Louisiana. An oil tracking model was added and is forced by the ADCIRC circulation output as well as by direct wind forcing. During the spill, the resulting set of computer models was used to forecast the future movement of the oil in the Gulf of Mexico. The oil was treated as a conservative tracer, so it was not lost due to evaporation or decomposition or any chemical process. Instead, it was allowed to move along the sea surface, at the same velocities as the currents. Satellite imagery was used to determine the existing locations of the oil spill, and then the model forecast its movement. Oil was seen to move along the continental shelf toward Florida, and onto the barrier islands and into the sounds along the Mississippi-Alabama-Florida coastline. It also moved into the marshes of southern Louisiana, and along the continental shelf toward Texas. The predicted oil movement was compared against the spill extent as observed by satellite imagery. After a week of simulation, the predicted oil overlaps the locations of the observed oil by about 60 percent, and thus the predictions show a reasonable match. In addition, the models were applied to hypothetical scenarios where oil spills are transported during the wind forcing of Hurricanes Katrina and Ike. Depending on the track of the land-falling hurricane and its associated winds, the model showed that oil can be pushed farther into the marshes and inland water bodies of southern Louisiana, or it can be pushed farther along the continental shelf toward Texas. Model results were generated in a data format that matches those utilized by US federal operation agencies (e.g., NOAA HAZMAT) thereby making the results accessible for use by these agencies. Broader impact: This project is a major step forward in the nearshore modeling of oil transport, and the technology developed should be useful if there is another spill in the future. The predictions can be trusted for several days, thus allowing emergency managers to understand where the oil may travel, and plan accordingly. The hypothetical hurricane scenarios emphasize that the Louisiana coastline is particularly vulnerable to environmental degradation due to flooding by oily waters.
