Ecological response to and management of increased ° ooding caused by climate change

River channels and their ®ood plains are among the most naturally dynamic ecosys-tems on earth, in large part due to periodic ®ooding. The components of a river’s natural ®ood regime (magnitude, frequency, duration and timing of peak ®ows) inter-act to maintain great habitat heterogeneity and to promote high species diversity and ecosystem productivity. Flood regimes vary within and among rivers, depending on catchment size, geology and regional hydroclimatology. Geographic variation in contemporary ®ood regimes results in river-to-river variation in ecosystem structure, and therefore in potential river ecosystem response to increased future ®ooding. The greater the deviation in ®ood regime from contemporary or recent historical con-ditions, the greater the expected ecological alteration. Ecological response will also depend on how extensively humans have altered natural river dynamics through land-use practices. Examples of human-caused changes in ®ood regime (e.g. urbanization, agricultural practices) provide analogues to explore the ecological implications of region-speci c climate change. In many settings where humans have severely modi- ed rivers (e.g. through leveeing), more frequent larger ®oods will work to re-establish connections with severed ®ood-plain and riparian wetlands in human-dominated river valleys. Developing and implementing non-structural ®ood-management policies based on ecological principles can bene t river ecosystems, as well as human society