Research Solutions Brief: Validating Floodplain Maps and Improving Flood Warnings at Iowa’s Bridges, SPR-RE22(016)-8H-00

(2024) Research Solutions Brief: Validating Floodplain Maps and Improving Flood Warnings at Iowa’s Bridges, SPR-RE22(016)-8H-00. Transportation, Department of

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Abstract

The expectation of improved flood warnings has become critical for many agencies and communities at a time when flooding is increasingly severe and widespread. Formulation of flood warnings for a specific area entails three major steps: A) forecasting the flood hazards, B) delineation of the flood maps, and C) assessment of the threats to human safety and economic losses within the inundated areas. The first step is executed with hydraulic and hydrologic modeling assisted by direct measurements of various water cycle variables. The second and third steps entail specialized analyses applied to a variety of physiographic, built infrastructure, social, and economic data collected over large scales. Consequently, the reliability of flood warnings is directly dependent on the model skills and the quality of the input data for the modeling and specialized analyses involved. In general, flood warnings have a high degree of uncertainty. Taking advantage on the unique resources available at the Iowa Flood Center (IFC), the present research idea is proposing an innovative path to significantly improve the flood-warning formulation (components B and C above) with focus on transportation infrastructure and resource allocation during flooding. Specifically, the research initiated by this project aims at: a) Assessing the quality of the statewide floodplain mapping at selected bridges across the state (with and without BridgeWatch warnings) by using the High-Resolution Satellite-based Maps (HRSM) available from third-party sources. The validated floodplain maps can significantly increase the protection for the statewide road network against the and indirect adverse impacts, including the loss of access to essential services needed during flooding. b) Developing a long-term plan to extend the BridgeWatch functionality to all flood-prone Iowa bridges at ungagged sites. The extension of the BridgeWatch functionality includes the innovative use of the IFC bridge sensors data that will inform on floodplain mapping extent at ungagged sites via the HRSM-based datasets.