Flood Mapping and Damage Assessment – A Case Study in the State of Indiana

Abstract

Flood mapping, damage assessment, and disaster remediation involve activities and efforts from a number of governmental agencies. Under the National Flood Insurance Act 1968, the Federal Emergency Management Agency (FEMA) is responsible for identifying flood hazards nationwide, publishing and updating flood hazard information in support of the National Flood Insurance Program (NFIP). Over a period of two decades, FEMA has produced over 90,000 flood hazard maps covering approximately 150,000 square miles of floodplain. Recently, about 75% of the flood hazard maps inventory became over 10 years old. In 2003, a program was initiated for flood hazard map modernization including the conversion of paper maps to digital format. Since flood hazard mapping is part of the NFIP, a variety of maps indicating various degrees of insurance risk and premium rating are produced. However, the basic hazard maps, indicating the 1 in 100 years (1%) floodplain and the 1 in 500 years flood (0.2%) outlines, are normally produced based on detailed hydraulic modeling of river reaches at the community scale. All flood maps are made available to the public through the FEMA Map Service Center. These maps can be purchased in paper or CD format and can be viewed online (http://msc.fema.gov/). Beginning on October 1, 2009, FEMA will provide only one paper flood map and the Flood Insurance Study (FIS) report to each mapped community. All other distribution of maps and Flood Insurance Study reports will be converted to digital delivery. FEMA will continue to provide free digital map products and data to federal, state, tribal, and local NFIP stakeholders. In addition to the FEMA mapping effort, which is specifically linked to the NFIP, some states have their own flood mapping programs. They produce flood “awareness” maps that simply show flood prone areas without specific depth or other flood hazard data for a particular flood event.