Flood Mitigation and Data Analytics Framework: Middle Cedar Case Study

Abstract:

Flood mitigation applications are critical to help protect communities in terms of loss of like and economic impacts. Benefit-cost analysis (BCA) is a common method to investigate the feasibility of costly flood mitigation measures such as property buyout application. The buyouts allow permanent loss reduction however it requires relatively higher cost compared to other mitigation measures. In this study, BCA of historical property buyouts and loss assessment of existing properties are investigated in the Middle Cedar watershed which is located in Eastern Iowa. Avoided losses are estimated using buyout data from Iowa Homeland Security Emergency Management Department (IHSEMD), existing parcel data from local tax assessors, flood maps from Federal Emergency Management Agency (FEMA), and historical gauge data from the United States Geological Survey (USGS). To explore future avoided loss, two different streamflow projections from two climate scenarios (A1FI-fossil intensive and A2-low emission) which allowed us to examine avoided loss in different circumstances. The study revealed that the average benefit cost ratio (BCR) for the majority of buyouts reached 0.86 between the date that buyouts are completed between 2009 and 2020. Long term projections (2020-2050) showed that more than half of the studied buyouts are expected to reach 4.72 BCR in moderate scenario and 6.3 BCR in major scenario. Historically avoided losses and loss for existing properties are shared through a web-based framework. The framework also allows exploration of statewide historical mitigation projects and buyouts by filtering location scope (statewide, county, city, and property level), program type (i.e. Hazard Mitigation Assistance Program, Individual Assistance Program), and time.