Managing flood risk, reliability and vulnerability

Floods, including flash and riverine floods, storm surges, snowmelt floods, ice jams and mud flows, are naturally occurring hazards that provide essential elements to the biodiversity and sustainability of ecosystems and many human activities.Floods are also the most taxing type of water-related natural disasters to humans, material assets, as well as to cultural and ecological resources -affecting about 520 million people and their livelihoods and claiming about 25 000 lives annually worldwide.The annual cost to the world economy of floods and other water-related disasters exceeds US$60 billion, while the cost of damage caused to cultural assets and natural resources is by no means quantifiable by economic scales.The Institute for Catastrophic Loss Reduction (Canada) and the Institute for Water Resources (USA) organized the International Symposium on Flood Defence (ISFD4) in May of 2008 in Toronto, Canada.The meeting offered a new perspective of flood risk management and assessment -one which recognizes flood risk reduction as an integral part of water resource management and which aims to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital systems.One of the main messages from the meeting is that the appropriate flood risk mitigation investment, and the redirection of resources into flood disaster prevention, offers significant economic benefits, as well as reduction in loss of life and property, improvements in welfare and social stability.This special issue combines two themes: integrated flood risk management and operational flood management.Tools like flood insurance, flood risk mapping, risk-based design of flood protection measures and similar are given detailed consideration in the context of integrated flood risk management.Operational issues are addressed through examples that describe flooding caused by hurricane Rita in the United States; floods in Tabasco, Mexico; the Australian experience with flood warning; and other.Papers in this special issue, and all conference contributions (available at http://www.ifi-home.info/isfd4/index.html), are acknowledging:that floods in their natural state play a vital role in support of economic and environmental sustainability; that costs associated with floods in terms of both lives lost and damages sustained continue to rise on a global scale; that societies of all types continue to occupy floodplains and delta areas that are highly prone to the incidence of severe flooding;