Flood Damage Assessment in Coastal Areas: Case Study of New York City

Floods are the most devastating natural hazards in the U.S that have caused significant economic damages. Estimating damages at different parts of the floodplain based on the flooding extent can be used to identify the vulnerable areas and properties to flood hazard. This may provide better preparation for effective flood risk planning and management. In this study, Geographic Information System (GIS) based approaches are used for estimating flood damages in Manhattan, the most strategic borough of New York City. For this purpose, a risk-based methodology is developed to quantitatively assess flood risk utilizing land use information and socio-economic data. Based on this methodology, two different models are used. The first one is a proposed GIS-based empirical-synthetic model, called Flood Damage Estimator (FDE). This model combines land use data along with other information to estimate flood damage. The results of this model are compared with the results of flood hazard analysis module in FEMA HAZUS software as the second model. This module uses different characteristics, such as ground elevation and storm surge elevations to estimate losses. For both methods, 100-year floodplain proposed by FEMA Flood Insurance Study (FIS) as well as floodplain developed by a distributed hydrologic model named GSSHA (Gridded Surface Subsurface Hydrologic Analysis) is used to determine the water inundation at different locations. Depth-damage functions are used to estimate the potential damage from flooding. 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 for HAZUS model.

Keywords:

Coastal Flood , Coastal areas , Risk Management , Flood damages , GIS , FEMA-HAZUS , GSSHA