Floods can increase the transmission of many communicable diseases, such as water-borne diseases like typhoid fever, cholera, and hepatitis A. The major risk for outbreaks associated with flooding is the contamination of drinking-water facilities, but the risk of disease outbreaks can be minimized if it is recognized and disaster-response organizations make delivering clean water a priority.
Floods may also indirectly lead to an increase in vector-borne diseases like malaria, dengue fever, yellow fever, and West Nile Fever through the expansion in the number and range of vector habitats. A vector is an organism that does not cause a disease itself but instead spreads infection by conveying pathogens from one host to another. Vector-borne diseases typically refer to illnesses transmitted to people by blood-sucking arthropods, mosquitoes, biting flies, and the like, or arachnids like mites or ticks. Standing water caused by heavy rainfall or river overflow can become breeding sites for mosquitoes and increase exposure to infections.
Hypothermia can be a problem, especially for children and the elderly, if people are trapped in floodwaters for long periods. Respiratory tract infections may rise in flood-affected populations due to exposure to the elements from loss of shelter.
The social and economic impacts of flooding are significant. If communication links and infrastructure like power plants, roads, bridges, wastewater treatment, electricity, education, and health care are interrupted, certain economic activities may come to a standstill and people may be forced to relocate. Displacement, loss of livelihoods, environmental contamination, disruption to business and social affairs and loss of property value in the floodplains leaves communities physically and economically vulnerable. Events such as the loss of family and friends leave psychological scars on victims and their families.
Catastrophic Flooding Events in the U.S. and Europe
On the morning of August 29, 2005, Hurricane Katrina struck the Gulf Coast. When the storm made landfall, it had a Category 3 rating on the Saffir-Simpson Hurricane Scale. While the hurricane itself did a great deal of damage, its aftermath was catastrophic. New Orleans’ levees and flood walls were breached in more than 50 locations, leaving approximately 80% of New Orleans flooded and displacing more than a million Gulf region residents. According to FEMA, Hurricane Katrina caused more than $161 billion in damage and ranks as the single most catastrophic natural disaster in U.S. history, although other storms have also been extraordinarily expensive. Industry sources reported that insurers paid out an estimated $41.1 billion on 1.7 million different claims for damage to businesses, vehicles and homes in six states. The NFIP paid more than $16.3 billion in claims, most of that for Louisiana-based losses. According to a 2006 Government Accountability Office report, however, at least $1 billion of those FEMA payments were improper and potentially fraudulent.
The U.S. Office for Coastal Management, which is part of the National Oceanic and Atmospheric Administration, reported that Hurricane Harvey in 2017 cost approximately $125 billion, second only to Hurricane Katrina. Hurricane Maria in 2017 was in third place with expenditures of $90 billion, followed by Superstorm Sandy in 2012 at $71 billion and Hurricane Irma in 2017 costing $50 billion. Hurricane Katrina was also first in flood insurance payouts, with an average paid loss of $97,140.
A report filed by the European Environment Agency based on an analysis of data collected from 1980 to 2010 concluded that significant increases in flooding are taking place now, and further, that annual flood losses will have increased five-fold by 2050 and up to 17-fold by 2080. The researchers blamed the increase primarily on a rise in the economic value of assets in flood plains and on increased rainfall due to climate change. A recent example is the June 2016 torrential rain event in Europe, causing evacuations and museum closures in Paris as the Seine River rose to 20 feet and inundated city streets. Several deaths in France, Germany and Belgium were reported. Insurance claims were estimated to be more than $2 billion.