Storm Hazard Modeling using TAOS & SLOSH
The Arbiter of Storms (TAOS)
Sea, Lake, and Overland Surges from Hurricanes (SLOSH)
The Department of Community Affairs is funding a comprehensive storm hazard modeling project using the TAOS model as part of the Local Mitigation Strategy. Storm hazard modeling using TAOS is part of an effort to produce a consistent state-wide assessment of storm hazard risk. It is useful to have a calculation of property risk that is consistent throughout the state.
FAQ - Table of Contents
1. Why is the State providing storm hazard data from the Arbiter of Storms (TAOS) model as part of the Local Mitigation Strategy?
The TAOS model is an integrated hazards model that will provide data at a higher resolution than the SLOSH model does for surge. This will enhance the local government's ability to do effective hazard mitigation planning. Currently, SLOSH model storm surge calculations are not available at the same resolution statewide, or in a standard Geographical Information System (GIS) format. The TAOS model can perform calculations of storm hazard risk for the entire state at one time, and the results are available for addition to the GIS data base. The use of TAOS storm hazard data for this part of the Local Mitigation Strategy effort does not infringe in any way on each county's prerogative to use other tools and information, including SLOSH model output, for vulnerability assessment or for planning. The new TAOS model data will enhance the information available to local governments. Local history and knowledge, used in conjunction with model data, will allow communities to best assess their vulnerability to storms.
2. What are some of the differences between the TAOS storm hazard model and the SLOSH storm surge model?
The SLOSH model calculates storm surge for an area of coastline called a basin. In order to provide complete coverage for the state's coastline, 11 separate SLOSH basins and models must be created and run. Unlike the SLOSH model which only calculates for storm surge, the TAOS model will also calculate an estimate of storm surge, wave height, maximum winds, inland flooding, debris and structural damage for the entire state at once. Furthermore, the model resolution for TAOS with respect to underwater and on-land data is much finer than for the SLOSH model. The resulting data from TAOS, because of the model's higher resolution and integrated approach to hazard analysis, is expected to be more suitable for hazard mitigation planning purposes. No computer model is perfectly accurate, so it is important to remember that calculations of storm surge from both TAOS and SLOSH contain some degree of uncertainty.
3. Is there a good reason to anticipate that TAOS model storm surge inundation boundaries will be significantly different than SLOSH model storm surge boundaries?
Storm surge physics are represented in a similar way by the TAOS and SLOSH models. There is good confidence that the coupled differential equations are being solved accurately in both models, so there is no reason to anticipate a large difference in the modeled storm surge. The TAOS model makes more extensive use of satellite and digital terrain data, and has a higher resolution. TAOS storm surge boundaries can be directly compared to SLOSH surge boundaries when the high-resolution TAOS model has been run in Florida. Where the two models agree, there is a high degree of certainty that both models give an accurate representation of storm surge; variations in storm surge elevation, and consequently in inland inundation boundaries, between the two models are not expected to be significantly different. The areas most likely to show model disagreement are at the boundaries between neighboring SLOSH basins.
4. Is the Department of Community Affairs buying a new hazard assessment software package?
Absolutely not. The Department of Community Affairs is investing in data only. The acquisition of this initial data set will probably allow for more frequent and timely statewide hazards analyses in the future.
5. Why can't the risk assessment be performed using the SLOSH model storm surge data?
Each SLOSH surge basin must be modeled individually, and the surge basins are modeled using a variable-resolution, parabolic, coordinate system. SLOSH model output is interpolated by hand onto contour maps that are then digitized. Consequently, SLOSH model output is not available at the same resolution in a consistent digital format for all locations in the state. The TAOS modeling effort will produce information about storm hazards throughout the entire state at the same resolution in a digital format that is convenient to use and compatible with most GIS (Geographic Information System) programs/data.
6. Will the State provide data for my vulnerability assessment?
Local governments should utilize existing data to begin their vulnerability assessment. Existing data includes, but is not limited to: damage survey reports from declared disasters; local disaster reports submitted in support of requests for State and Federal disaster declarations; flood insurance rate maps (FIRMs); repetitive loss data; SLOSH modeling results; insurance claims; interagency hazard mitigation team reports; Federal, State and Local after action reports; and newspaper articles and other anecdotal information. The State can supplement this data in some instances, and intends to provide vulnerability data from the TAOS model in the summer of 1998 to assist local governments in cross-verifying existing data.
7. Can local governments use SLOSH storm surge data for their community vulnerability assessments?
Absolutely. The risk assessment is only a part of the community vulnerability assessment. Local governments are encouraged to use local history and knowledge, SLOSH storm tide maps, FIRM flood maps, and TAOS model output as it becomes available to produce the best possible assessment of community storm hazard vulnerability. Vulnerability assessments should also include other applicable potential hazards, such as tornadoes, lightning, dam failure, and hazardous materials.
8. Will having additional storm hazard data change Department of Community Affairs policy or planning activities?
No. TAOS model data is being used exclusively for the risk assessment component of the Local Mitigation strategy, and as an additional tool to help local governments identify cost-effective mitigation projects in their communities. The TAOS model is not being used for operational, evacuation or land use planning activities. Therefore, the use of TAOS data for risk assessment will not have an impact on the current delineation of any evacuation zone and will have no effect on the extent of the Coastal High Hazard Area in any county.
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