50 Frequently Asked Questions About Floods and Their Answers
What is this event actually? How is it different from a flash event? Flash water surges are the most dangerous type of flood because they combine the destructive power of a huge, moving body of water with immense speed. Flash events usually develop rapidly, giving residents little time to evacuate. In particularly steep, clay-earth areas or in regions that receive a lot of rainfall, a flash flood can form in under an hour. Such an event can put countless human lives in danger extremely rapidly.
A "regular" flood, on the other hand, refers to any buildup of water that overcomes the banks, shoreline, levees, beach, embankment, break wall, or other natural or manmade artifacts or formations that generally keep that water at bay. Such a water buildup is still dangerous, as it can submerge homes, cars, people, and animals. But such a disaster event does not usually involve water that is moving as rapidly as in the case of a flash event.
Rushing water, moving with inertia and a force unparalleled by any machinations of man, it's difficult to comprehend the sheer power of a disaster like this. Floods are the natural disaster that can literally force homes off of their foundations and push them across the ground. Such events can cause immense harm, destroying anything and everything in their path. Of all the natural disasters, these ones also exert the greatest cost in human life. The two worst natural disasters in recorded history were both floods.
A The National Severe Storms Laboratory defines events like these as such “Flooding is an overflowing of water onto land that is normally dry. Floods can happen during heavy rains, when ocean waves come on shore, when snow melts quickly, or when dams or levees break. Damaging flooding may happen with only a few inches of water, or it may cover a house to the rooftop. Floods can occur within minutes or over a long period, and may last days, weeks, or longer. Floods are the most common and widespread of all weather-related natural disasters.”
The best way to determine if your home is in an at-risk zone is to check with your local county or township. They will have maps that indicate which homes are at risk for water surges and which aren’t. Keep in mind though, you can still be at risk for water surge even if you don’t live in a flood zone.
According to Flood Smart, a program organized by FEMA, “Flood insurance covers losses directly caused by flooding.... Property outside of an insured building. For example, landscaping, wells, septic systems, decks and patios, fences, seawalls, hot tubs, and swimming pools. Financial losses caused by business interruption.” It’s important to prepare for and protect against such events. Holding an insurance policy that can cover the repairs to your home should not be your first or only line of defense against such disaster events (though it is helpful).
The various types of water risk zones are given specific designations to differentiate them. These designations also determine whether or not homeowners will need to purchase insurance as a part of their mortgage. According to one resource, “AE flood zones are areas that present a 26% chance over the life of a 30-year mortgage, according to FEMA. Since these areas are prone to flooding, homeowners with mortgages from federally regulated lenders are required to purchase flood insurance through the NFIP."
Flood Zone X refers to an area that is outside the 500-year risk area, and which is protected by a levee from the 100-year risk. This is a moderate risk area, meaning that purchase of a home in this area may require insurance for many home mortgage lenders to agree to offer a mortgage for the home.
According to one resource, this region is defined as follows “Zone A is the flood insurance rate zone that corresponds to the 1-percent annual chance floodplains that are determined in the Flood Insurance Study by approximate methods of analysis. Because detailed hydraulic analyses are not performed for such areas, no Base Flood Elevations or depths are shown within this zone. Mandatory flood insurance purchase requirements apply.”
The great water surge event of Noah may have occurred around 2,900 BCE.
Such a plain is defined by an area of low-lying ground that is adjacent to a river. This geographic region will have been formed mainly by river sediments, and even if it is a good distance away from current river systems, such a plain is still subject to flooding.
Such a warning is usually suggestive of low-risk rainfall and puddling or pooling. Such warnings are usually issued when one to two inches of rain are expected.
You might not have much time to prepare for such a disaster event, so it’s important to be hasty and prioritize your time. One government resource suggests that people do as much research and preparation during normal, dry times, so that when a massive water event does occur, they are sufficiently prepared.
According to one organization, “Make a plan for your household, including your pets, so that you and your family know what to do, where to go, and what you will need to protect yourselves from flooding. Learn and practice evacuation routes, shelter plans, and flash flood response. Gather supplies, including non-perishable foods, cleaning supplies, and water for several days, in case you must leave immediately or if services are cut off in your area. Keep important documents in a waterproof container. Create password-protected digital copies. Protect your property. Move valuables to higher levels. Declutter drains and gutters. Install check valves. Consider a sump pump with a battery.”
People often wonder what the difference is between a “watch” and a “warning.” According to www.weather.gov: “A Flash Flood Warning is issued when a flash flood is imminent or occurring. If you are in a flood prone area move immediately to high ground. A Flood Warning is issued when flooding is imminent or occurring. A Flood Watch is issued when conditions are favorable for a specific hazardous weather event to occur. A Flood Advisory is issued when a specific weather event that is forecast to occur may become a nuisance.”
One of the reasons why water-related disaster events are the most common type of natural disaster is because the conditions which form such events occur quite frequently. Floods occur when heavy rainfall exceeds the ability of the ground to absorb that sheer amount of rain. Virtually any severe rainstorm has the potential of causing a water surge. Such surges also occur when enough water accumulates in streams, rivers, and lakes for the water to overflow the river banks or the edges of the body of water. Another cause of such events is ice jams and snowmelt. A deep snowpack that melts rapidly can cause flooding to occur. When spring rains exaggerate snowmelt, flash water surge can occur.
Wetlands are immensely important to the local ecosystem and, as it turns out, to protecting human life and property. Wetlands temporarily store water and slowly release it into the environment. Wetlands are a natural sponge, able to soak up storm waters and prevent water runoff and damage to surrounding human habitation.
It is almost impossible to guarantee the prevention of such a natural disaster. Ditches, fields, levees, dams, rain gardens, and water retention ponds can help. However, communities must ask the question, “To what extent are we willing to alter the surrounding environment and ecosystem?” It might be more safe to simply not build in extremely water-prone areas, and to instead let nearby wetlands protect the region from excessive water flow.
The name of such an event is an effort to simplify a more complex natural event. Basically, labeling such an event “A 100 year event” is an easy way of categorizing a type of water surge that only has a 1% chance of occurring each year, hence the idea that that level of water flow is only supposed to occur once every 100 years.
One of the reasons why water flow disasters are the most destructive natural disaster in the United States is because they occur in every U.S. state and territory. They are a threat anywhere in the world that experiences rain. Even arid regions can experience such events because a sudden rainfall can overwhelm dry creek beds and flow into local communities.
Such events are caused by excessive rainfall in a certain area. They can also be caused by the release of water held by an ice jam or some other type of blockage. Such events usually come about during or after slow-moving thunderstorms that deposit heavy rains on a concentrated area. Disasters like these can also result from hurricanes or other tropical storms.
Such plains are formed by erosion, i.e., the gradual cutting of a steam or river into its banks. This process occurs over countless years, sometimes thousands of years, to shape a significant region around a river. As the plain is formed, it can also experience water-level rises during particularly bad storms.
The best way to protect yourself and others when it comes to dangerous rises in water levels is to be aware and informed of their risk and to have an escape route in place.
1). Know if you live in a flood plain. Are you at risk for a flood? Study local maps and determine if you live in such a plain. Most U.S. counties have detailed flood plain maps, and many counties won't even let new homes be constructed in such plains.
2). Be warned. The best chances for surviving a disaster-level water event come from knowing when a water surge is coming. Invest in an NOAAA radio, and make sure your cell phone emergency alerts are turned on.
3). Have an escape route. You need to know where you will evacuate to if the water levels begin to rise. Where can you drive to that is higher in elevation than where you currently live? How can you drive there without having to drive through lower elevation areas?
4). Learn the terminology. Know the different types of warnings. The National Oceanic and Atmospheric Association monitors water level conditions and sends out alerts if a water level rise seems likely. For example, a flash event "watch" (or a flood watch) means that flash flooding or flooding is possible within the designated watch area. Be alert. A flash event "warning" (or a flood warning), on the other hand, means that flash flooding or flooding has been reported and is imminent. If you hear such warnings for your area, take necessary precautions at once, and get to higher ground!
5). "Turn around, don't drown." According to the NOAAA, most flooding deaths occur when people attempt to drive their cars into or through water-covered roadways. If you are attempting to evacuate an area and you encounter such a road, turn around and find an alternate route. Never attempt to drive on or through a road that has water flowing over it..
A Floods are deadly and dangerous. If such a disaster event is coming your way, do everything you can to evacuate safely. If you cannot evacuate, seek higher ground wherever you are. Never try to swim in or drive through such waters.
This simply refers to any region which may experience a water level rise that may be a risk to local human habitation.
According to one safety management group, “The main cause of flooding in urban areas is poor or lack of drainage. High intensity rainfall overwhelms sewage and drainage within cities and neighborhoods, filling the streets in a dangerous mix of sewage and floodwater. Urban flooding is a slower process that hinders transportation and may damage daily activities but rarely results in deaths.”
There is not much humans can do to proactively prevent disasters like these from occurring. Rather, it’s more about what humans don’t do. Case in point, when humans pave over natural soil with parking lots, roads, and buildings, they are making it more difficult for rainwater to seep naturally into the soil. Urban development actually makes serious rainfall worse, not better. Preserving wetlands and investing in water-pervious paving methods can prevent serious disaster events from occurring.
This refers to an area that is only expected to receive higher-than-normal water levels once every 100 years. Another way to look at it is that such regions only have a 1% chance of experiencing disaster-level water events each year.
This is simply a type of water event that involves the rapid rise of water levels and disbursement of water into a region with little to no warning.
The term simply refers to an area in and around a river or stream that is subject to rising water levels during excessive rain and other natural events.
This refers to a powerful surge of water onto land, usually tidal water in the ocean.
This refers to an area with minimal hazard for serious water runoff events.
Turn around, don’t drown! That is the catch phrase to remember. If safe evacuation over roads that do NOT have water on them is possible, then evacuate. But if roads to higher ground are not passable, turn around, and try to find higher ground somewhere else. Sometimes, the highest ground available will be the second floor or roof of you home, so keep that in mind as a potentially good place to wait out a storm event.
Natural levees can help prevent excessive water events from occurring. However, if the natural levees fail, it can often result in a serious water runoff event.
According to the Flood Observatory (recording such events since 1985), the average duration of water above normal levels is 9.5 days. While floods can form very quickly (particularly in the case of flash floods), they often linger for many days at a time before the water level returns to a normal range. A flood is still quite dangerous, even if the water is no longer moving as rapidly.
Such an event can bring walls of water from ten to twenty feet high. A car can be taken away by such water in as little as two feet of water, and entire homes can be shifted off their foundations by particularly strong surges. Such a disaster event can cover a large swath of land too, depending on the geography of the region.
This term refers to the water level, as read by a stream gauge or tide gauge, for a body of water at a particular location, at a particular time. As the measurement varies, experts are able to monitor the various stages of excess water flowing into or out of that region at any given time.
The National Severe Storms Laboratory defines these events as such: “Flooding is an overflowing of water onto land that is normally dry. Floods can happen during heavy rains, when ocean waves come on shore, when snow melts quickly, or when dams or levees break. Damaging flooding may happen with only a few inches of water, or it may cover a house to the rooftop. Floods can occur within minutes or over a long period, and may last days, weeks, or longer. Floods are the most common and widespread of all weather-related natural disasters.”
Such events are most likely to occur in areas that experience significant rainfall or in coastal and river regions. But disasters like these can technically occur anywhere that has rainfall.
A 500 year event such as this is one that only has a 0.2% chance of occurring each year, hence the likelihood of such a disaster event only occurring once every 500 years.
Do not enter standing water that is leftover from such an event, as it may be carrying an electrical current. Wait until all of the water has receded before you begin the cleanup and recovery process.
If the water surge is so bad that water begins to come into your home, there are several things you must do, and quickly! Turn off the electricity to your home, to prevent electrical currents from traveling through the water. Evacuate the premises if you are able to plot out a safe route along a road that does NOT have water flowing over it. If that is not possible, call for help. While waiting for help to arrive, seek higher ground in the second floor of your home, or on the roof, if necessary.
There are some basic, life-saving rules to follow during a sudden water surge event. From the Centers for Disease Control and Prevention: “Gather emergency supplies, including food and water. Store at least 1 gallon of water per day for each person and each pet. Store at least a 3-day supply. Listen to your local radio or television station for updates. Have immunization records handy (or know the year of your last tetanus shot). Bring in outdoor possessions (lawn furniture, grills, trash cans) or tie them down securely. If evacuation appears necessary, turn off all utilities at the main power switch and close the main gas valve. Leave areas subject to flooding such as low spots, canyons, washes, etc. (Remember: avoid driving through flooded areas and standing water.)”
This is an event in which low-lying coastal regions are submerged by sea water. This can occur as a result of hurricanes and other tropical storms, or as a result of particular high tides or storm surges.
River plains and coastal regions are the areas most susceptible to such disaster events. However, a disaster like this can actually occur just about anywhere that experiences rainfall. Even in the desert, immense water runoff has been known to occur.
They are primarily dangerous because they occur so rapidly and can often catch people off guard. Particularly in rural areas with few roads, such a disaster event can quickly trap people in an isolated region, often giving them no way to safely evacuate.
Wetlands are extremely important! They should not be altered, drained, or paved over. They act as natural sponges that absorb excess rainwater and stormwaters. Paving over them makes water runoff worse, creating more severe water surge events as a result.
According to the records, the 1931 flooding of the Yangtze River in China (called the Central China Floods of 1931) comes first for the worst natural disaster in human history. Anywhere from 2 million to 3.7 million people died because of this flood. One of the reasons for the huge death toll is that the flood covered a massive swath of land, about 70,000 square miles all in all.
One of the reasons why water level rises are the most common type of natural disaster is because the conditions which form such events occur quite frequently. Surges occur when heavy rainfall exceeds the ability of the ground to absorb that sheer amount of rain. Virtually any severe rainstorm has the potential of causing such an event. Floods also occur when enough water accumulates in streams, rivers, and lakes for the water to overflow the river banks or the edges of the body of water. Another cause of floods is ice jams and snowmelt. A deep snowpack that melts rapidly can cause surging to occur. When spring rains exaggerate snowmelt, flash flows can occur.
Floods can cause immense damage to anything in their path. Flash floods, in particular, are quite devastating, as they tend to involve fast-moving water. Densely populated areas are also at higher risk for crisis-level incidences because buildings, highways, and parking lots increase runoff by reducing the amount of rain absorbed by the ground.
If a thunderstorm lingers over an area for an extended period, it can cause a nearby stream with just a few inches of water in it to rise ten feet or more in under an hour. That poses a particular risk to people who are camping or recreating near bodies of water during intense rainfall.
The primary cause for concern with floods are the legitimate risk of drowning. Such events occur quickly, they usually involve fast-moving water, and they are quite unpredictable. People who get caught in a disaster like this are often unable to get out of the water, and they drown. In the United States, floods kill more people than tornadoes, hurricanes, or lightning.
All such events are dangerous, but flash floods are by far the most dangerous. With that in mind, the following are the regions of the U.S. where flash floods are most likely to occur:
- Densely populated areas. As mentioned earlier, the buildup of concrete structures, essentially "paving over the world," makes stormwater runoff conditions much worse.
- Areas near rivers. These regions are at risk for serious water level rises. Even when levees are built near flood-prone rivers, such installations are not always effective at preventing the water level from rising over the levee.
- Dam failures. When a dam fails, this causes a sudden and destructive surge of water to plummet downstream. Such an event can be particularly devastating, as people living nearby usually have little to no warning of such an event occurring.
- Mountainous regions, steep hills, and clay-like soil. Steep areas are more prone to water level rises, particularly in the southeastern United States, where the soil is more clay-like and not as absorptive.
- Canyons and river beds. Out west, a dry creek bed or a canyon may seem like a safe place to recreate. But this is not always the case. During incidences of heavy rainfall (even rainfall occurring far away from campers upstream), dry creek beds and canyons can fill with water rapidly, posing an immense risk to those nearby.
- Recent burn areas. An area that has been burned recently (such as a coordinated burning in a forest) is at risk for water surges, as much of the vegetation which would have captured flood waters will have been burned away.
Yes, they absolutely can! One of the more sinister risks of water level rises is that the water levels can begin to recede, and there can be the appearance of safety. Then, suddenly, a second rainstorm can occur upstream, or a levee can break, or a dam fails, and floodwater levels rise again. This is why it is critical not to approach a recently flooded area until public health and safety experts say it is safe to do so.
The two most devastating natural disasters in recorded history were both the result of sudden increases in water levels. According to the records, the 1931 flooding of the Yangtze River in China (called the Central China Floods of 1931) comes first for the worst natural disaster in human history. Anywhere from 2 million to 3.7 million people died because of this disaster event. One of the reasons for the huge death toll is that the flood covered a massive swath of land, about 70,000 square miles all in all.
The second-worst natural disaster in human history was also a flood, and it also occurred in China. This was the 1887 Yellow River Flood, a natural disaster that killed anywhere from 900,000 to 2 million people. The event was partially caused by human interference, as the Yellow River had risen above and away from nearby farmland by a series of dikes. When heavy rains surged the river, it spilled over the dikes and put about 5,000 square miles underwater.
As for such disasters in the United States, the worst one was undoubtedly the 1889 flood in Johnstown, Pennsylvania. In this disaster, an upstream dam failed, and a wall of water 40 feet high and a half-mile wide came roaring down upon the Appalachian town of Johnstown, killing 2,209 people within minutes.
Most scientists believe that instances of water surge will become more frequent and more intense in the coming years. As it currently stands, an increasing number of coastal and inland communities are already experiencing higher numbers of events of this kind.
There is a growing body of evidence that, as the effects of climate change become more pronounced, floods will become more frequent and more intense. Quoting the Natural Resources Defense Council, “As the IPCC (Intergovernmental Panel on Climate Change) noted in its special report on extremes, it is increasingly clear that climate change 'has detectably influenced' several of the water-related variables that contribute to floods, such as rainfall and snowmelt. In other words, while our warming world may not induce floods directly, it exacerbates many of the factors that do. According to the Climate Science Special Report (issued as part of the Fourth National Climate Assessment, which reports on climate change in America), more flooding in the United States is occurring in the Mississippi River Valley, Midwest, and Northeast, while U.S. coastal flooding has doubled in a matter of decades.”
It would seem that floods will get worse. They'll become more frequent, and the floods that do occur will likely be more devastating than they were before.