An Examination of Flood Damage Data Trends in the United States

Abstract

At this time an understanding of flood damages remains elusive from the perspective of a quantitative understanding of factors speculated to contribute to flood damages in the United States (Pielke 2000). As of September 2001, the Corps managed 383 lake and reservoirs (these serve multiple functions with flood control as a major function), and constructed or controlled 8,500 miles of levees. Total flood control expenditures from 1928 through 2000 amounted to $122 billion adjusted for inflation using 2001 dollars (Civil Works Information Paper 2002). Yet, despite all of these investments, flood damages in the U.S. have increased.1 Suspected causes of increasing flood damages include: climate variability and climate change, population growth and development, increasing personal wealth, violations of flood management guidelines, and federal policies. However, none of these factors had been decisively proven or disproved as the reason behind increasing flood damages. Assessing empirically the reasons why flood damages are increasing is extremely difficult because of factors such as a lack of data on population and development within floodplains, and a poor understanding of the performance of flood control measures and implications of those and other floodplain management policies on land use decisions in floodplains. Given these uncertainties, the purpose of this paper is to examine how existing flood damage data can help us understand national flood damage trends. In order to fulfill this purpose, this paper evaluates the existing empirical analysis of flood damage trends, and considers the implications of data limitations for understanding flood damage trends and supporting floodplain management decision-making. This analysis is presented as three key questions: ÔÇó Where do the data come from? ÔÇó What can the data tell us? ÔÇó What canÔÇÖt the data tell us?