Coastal Flood Damage Estimator: An Alternative to FEMA’s HAZUS Platform

Abstract

Floods are the most devastating natural hazards in the United States, and these events lead to significant economic consequences. Estimation of damages and losses at different parts of the floodplain can be used to identify the vulnerable areas susceptible to flood. Floodplain maps combined with damage assessment could identify high-flood-risk areas and present a platform to develop guidelines and zoning resolutions for proper land use, building new infrastructures, and placing and retracting residential areas. In this study, a risk-based methodology is proposed to quantitatively assess damages. For this purpose, a geographic information system (GIS)–based approach is used as an alternative to more complex software packages. The system is called a flood-damage estimator (FDE) and utilizes empirical synthetic depth-damage functions, land-use data, digital elevation model (DEM), raster maps (for featuring the characteristics of the properties at flood risk areas), and floodplain extent for the region in order to estimate flood damage. The results from this model are compared with the results of flood hazard analysis module in the FEMA HAZard United States (HAZUS) software. This model uses different characteristics, such as ground elevation and storm surge elevations to estimate flood damages and losses. In both models, a 100-year floodplain proposed by the FEMA flood insurance studies (FISs) of 2007 and 2013, as well as floodplain developed by the gridded surface subsurface hydrologic analysis (GSSHA)–distributed hydrologic model, are used to determine the flood water depth at different locations. This hydrologic model provides input from simultaneous consideration of inland and coastal flooding to the damage estimation model. The proposed methodology is applied to Manhattan. The results show the significant value of combining GIS-based models with damage-risk analysis to provide a flexible and simple platform for damage estimation as an alternative to the HAZUS model. Flood-risk maps created based on the damage estimation are of great use and importance in proper planning for land use and setting priorities for allocation of financial resources in recovery and reconstruction plans.