Using Hec-Fia to Identify the Consequences of Flood Events (PAP014378)

Código

PAP014378

Autores

William Parker Lehman, Christopher N. Dunn, Miles Light

Tema

Flood risk management in mega cities

Resumo

As the world's population grows the need for development increases; this need for additional space causes land use decisions to be made that can increase flood risk. This pressure to expand creates many changes in our floodplains that significantly increase the exposure of the public and the overall economy of a region to flood hazards. Urban sprawl not only increases the number of structures and thus value exposed in the floodplain, it also increases the population exposed within the floodplain. Additionally, the urbanization of regions increases the rainfall runoff relationship thus increasing flood risk from a hydrologic perspective, and can limit the feasibility of structural flood risk mitigation measures. All of these simultaneous changes in the floodplain can create significant risk for the future. To evaluate the consequence portion of the risk equation, the United States Army Corps of Engineers' Hydrologic Engineering Center developed the HEC-FIA (Flood Impact Analysis) software, HEC-FIA is used to estimate current and future floodplain consequences with uncertainty. By estimating the consequences, the benefits of existing and future flood risk management measures can be evaluated and compared. HEC-FIA utilizes geospatial datasets to build structure inventories and then assigns values and population per structure. Using this information and geospatially derived flood depth grids (provided by a piece of hydraulic software), HEC-FIA estimates direct economic, indirect economic, agricultural, and life loss consequences for flood hazards. HEC-FIA can compute results for a single event in either deterministic mode or in uncertainty mode which utilizes a Monte Carlo approach. The user can define the uncertainties about any structure in the floodplain in many ways, and each has various impacts on the different consequence calculations. For example, foundation heights, structure values, and depth damage relationships impact economic consequences, while foundation heights, warning issuance times, and fatality rates all can be defined with uncertainty to impact the life loss calculations. HEC-FIA can also be linked into HEC-WAT (Watershed Analysis Tool) with the FRA (Flood Risk Analysis) compute option to randomize the events being evaluated in HEC-FIA so that hydrologic, hydraulic, geotechnical, and economic uncertainties can all be represented and evaluated by alternative within the floodplain. This capability allows users to evaluate current and future risk in a changing environment. This paper will describe how HEC-FIA can be utilized to help evaluate the consequences for various alternatives within a floodplain.