Description of event

Floods are the most common natural disasters. They cause greater mortality than any other natural disaster. Worldwide, floods account for approximately 40% of natural disasters. In the United States, approximately 146 deaths are caused by floods each year, the majority associated with flash floods. The National Oceanic and Atmospheric Administration (NOAA) estimates an average $8.2 billion in damages per year in the United States because of floods, not including damages from the storm surges of hurricanes.

Floods continue to be the number one natural disaster in the United States in terms of lives lost and property damage. In 1889 more than 2200 deaths were due to flash flooding from a dam break in Johnstown, Pennsylvania. In 1976 a 19-foot wall of water near the Big Thompson River near Denver, Colorado, killed 140 people camping nearby. More recently, in 2005, Hurricane Katrina resulted in 1833 deaths, with an associated $148 billion in total damages and costs. Current estimates of the effects of the 2012 “Superstorm” Sandy in the United States are 159 deaths and $65 billion in damages. The 2010 monsoon floods in Pakistan resulted in 1985 deaths, with estimates of $9.5 billion in economic effects.

Floods may be caused by an abundance of rainfall, melting snow, or the expanding development of wetlands, which reduces absorption of rainfall. Flash floods occur within 6 hours of a rain event, after a dam or levee fails, or after the sudden release of water from an ice or debris jam. Flash floods are the leading cause of natural disaster-related death. Most communities in the United States can experience flooding. In fact, flash floods occur in all 50 states. Communities at greatest risk are those in low-lying areas, near water, and located downstream from a dam. In June 2008 the floods in Eastern Iowa resulted in 18 deaths and 106 injuries. The flooding occurred in known flood plains, resulting in the emergent evacuation of a hospital in Cedar Rapids, Iowa.

Pre-Incident actions

Hospitals should determine whether they are located in a flood-prone area. The National Weather Service issues flood watches and warnings, organized by state, and publishes these listings at www.nws.noaa.gov . These projections are based on precipitation and lake and river levels. Flood watches are posted 12 to 36 hours before possible flooding events. Flood watches indicate that a hazardous event is occurring or will occur within 30 minutes. A flood watch should be used for early evacuation planning.

Evacuation routes should be planned and practiced. For planning purposes, flood hazard maps are available from the Federal Emergency Management Agency at http://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping . The usual routes of access to and from the hospital may be flooded; therefore alternative routes should be planned. During intense flooding lasting multiple months in southern Africa in 2008, flooded roadways and downed bridges isolated patients from access to health care in Zambia, leaving them without access to acute and chronic care for months. As with any natural disaster, transport times will likely increase, and hospital personnel should expect ambulance arrival without prior dispatch. There will be greater reliance on alternative means of transport, including aeromedical and marine units.

An emergency communications system should be available. Communication lines among hospitals, prehospital staff, and patients may be affected by floods. Telephone lines, 911 dispatch lines, and emergency medical service communication with hospitals may be impaired. Create a plan for redundant communications capabilities, including two-way radios and dedicated channels, cell phones, and Internet connectivity. An emergency communications system plan should be in place to request further staffing, services, or evacuation assistance. Awareness of social media resources should also be incorporated in community and hospital communications plans. Use of sources such as Twitter and Facebook has been utilized to support both information sharing from health agencies and reporting of health and rescue needs by victims during various disasters, including the Haiti Earthquake in 2010 and the 2009 flu pandemic in the United States. Reliable information on affected areas may be shared by local and state emergency management agencies as well as other health care partners and first responders.

Floods are long-term events that may last days to weeks, or longer. Therefore at least 72 hours of disaster supplies, including nonperishable food and water, should be available. Emergency kits should also include a portable battery-operated radio, flashlights, batteries, first aid kits, personal sanitation items, local maps, and a cell phone with charger or spare batteries, among other items. Further recommendations may be found online at www.ready.gov/kit. ⁴

Post-Incident actions

During a flood, battery-operated radios or televisions should be used. The NOAA Weather Radio broadcasts warnings from the National Weather Service 24 hours a day. Hospitals not equipped with the special radio receiver to pick up the signal can obtain timely information at http://www.nws.noaa.gov/view/nationalwarnings.php or from television and radio news services.

Hospital staff and patients should immediately be evacuated according to a preestablished disaster plan. If no plan is in place, seek shelter at higher ground. Avoid walking or driving through floodwater. The force from 6 inches of floodwater can cause a person to fall. Cars can easily be swept away by just 2 feet of floodwater. Research from the Georgia flood in 1994 showed that 71% of flood deaths were associated with submersion in vehicles.

Medical treatment of casualties

Approximately 0.2% to 2% of flood survivors will require urgent medical care. The main cause of death during floods is drowning, with victims typically found some time after the flood recedes. Because it is often difficult to reach victims during the acute phase of a flood, it is relatively uncommon for near-drowning victims to present to emergency departments. Fast-flowing floodwaters carry cars, trees, and other large debris that can result in trauma, including orthopedic injuries and lacerations. ^, In addition, there have been reports of flood-waters displacing snakes and other animals, resulting in increased animal bites. ^, Moreover, the preponderance of water during the event and still water post-event results in an increase in insect bites and vector-borne illnesses. Floodwaters also may contaminate the local water supply and sewage system. ^,

The Centers for Disease Control and Prevention analyzed data from emergency departments in 20 hospitals during Hurricane Floyd in North Carolina during September and October 1999. The medical examiner found that 52 deaths were directly related to the storm. Four causes of injury or illness accounted for 63% of all emergency room visits during this period: orthopedic and soft tissue injury (28%), respiratory illness (15%), gastrointestinal illness (11%), and cardiovascular disease (9%). The majority (24 of 52, or 67%) of deaths were due to drowning, primarily associated with vehicles. There were 19 cases of hypothermia, and 10 cases of carbon monoxide poisoning. There was also an increase in suicide attempts, violence, dog bites, and arthropod bites, compared with the same period the prior year. Finally, five deaths occurred among prehospital personnel.

Unsurprisingly, drowning is the primary cause of death during floods. Patients who are submerged in cold water for 40 minutes have been successfully resuscitated to attain complete neurologic recovery secondary to the neuroprotective effects of hypothermia. Therefore, cardiopulmonary resuscitation should be performed as soon as possible after securing the scene. Cervical spine injuries should be suspected, and immobilization should be maintained. The patient should be rewarmed using external and internal rewarming techniques, as indicated. Resuscitation efforts should be continued until the patient’s temperature is 32 °C to 35 °C (90 °F to 95 °F); at that point, decisions regarding the utility of continuing resuscitation are made.

Floodwaters carry a large amount of debris, such as cars and tree limbs, and result in traumatic injuries. Orthopedic injuries should be reduced, splinted, and managed accordingly. Most injuries during floods that require urgent medical attention include lacerations, rashes, and ulcers. These wounds are contaminated and should be conservatively managed by irrigation and healing by secondary intention. Among those lacerations that are closed primarily, the majority require reopening secondary to infection.

Floods cause water contamination and an increase in vector-borne illnesses. Water contamination often results from damage to the water purification and sewage systems. Contaminated water sources result in waterborne disease transmission, including Escherichia coli, Shigella, Salmonella, and hepatitis A virus. The large areas of stagnant water that typically remain days or weeks after the initial flood event create a breeding medium for vector-borne illnesses.

Floodwaters may also result in the spread of chemicals stored above ground. In addition, temporary shelters to house those displaced by flooding may result in crowded and unsanitary living conditions, increasing the incidence of gastrointestinal illness, among other infectious illnesses.

The force from floodwaters may also down power lines, flood electrical circuits, and submerge electrical equipment, increasing the risk of fires and electrical hazards. ^,

Finally, victims of floods, as well as other natural disasters, are at an increased risk of mental illness and substance abuse. Analysis after the 2007 flood season in the United Kingdom indicated the prevalence of all mental health symptoms was up to five times higher among those with flooding in their homes. Those with negative financial consequences were also more likely to report psychological complications.