One billion people one sixth of the global population, the majority of them among the world's poorest inhabitants are estimated to live today in the potential path of a 100-year flood and, unless preventative efforts are stepped up worldwide, that number could double or more in two generations.
Floods presently impact an estimated 520+ million people per year worldwide, resulting in estimates of up to 25,000 annual deaths, extensive homelessness, disaster-induced disease, crop and livestock damage and other serious harm. UNU says unsustainable land use and other human actions aggravate the situation.
The greatest potential flood hazard is in Asia. Every year for the past two decades, more than 400 million people on average have been directly exposed to a flood. Between 1987 and 1997, 44% of all flood disasters worldwide affected Asia, claiming 228,000 lives (roughly 93% of all flood-related deaths worldwide). Economic losses in the region in that decade totaled US $136 billion.
The fast-growing cost to the world economy of floods and other weather-related disasters (now $50 to $60 billion per year, much of it in developing countries) is roughly equal to the global development aid provided by all donor countries combined. The flood-related death toll represents 15% of all natural disaster-related loss of life. Even the most advanced nations are affected: the 2002 floods in Europe killed roughly 100 people, affected 450,000 people and left $20 billion in damages; the US, which suffered 50 deaths and $50 billion in damage in the Mississippi River flood of 1993, has averaged 25 flood deaths annually since the 1980s.