Each year, floods cause enormous damage to property and kill thousands of people around the world. During the 1990s alone, freshwater flooding affected more than 1.4 billion people and caused about 100,000 deaths (Jonkman 2005). Worldwide, insured losses due to floods topped US$2 billion in 2008 (SwissRe 2009), making them the second-most expensive type of natural catastrophe (exceeded only by damages caused by tropical storms). In addition to the threats they pose to human communities, major floods are also important geological and biogeochemical agents that influence rates of erosion and sediment transport (Molnar 2001), redistribute organic matter and nutrients to downstream reaches (Velasco et al. 2006) and homogenize ecological processes and biological communities within floodplain systems (Thomaz et al. 2007).