What causes flooding?
Here are just a few: Heavy rainfall Ocean waves coming on shore, such as a storm surge Melting snow and ice, as well as ice jams Dams or levees breaking. Too much rain or melting snow are the main causes of floods. Sometimes the soil in the ground can make a flood worse. This is because when rain falls, the soil usually soaks it up like a sponge. But when the soil can’t soak up any more water., it will send extra water into a river.
Floods are a powerful force on our planet. In natural systems, floods play an important role in ecosystem functioning, such as by recharging groundwater systems, filling wetlands, and what cause floods to happen promotion of breeding, migration, and dispersal of numerous species . In natural ecosystems, there is a lot of resiliency to the majority of flood events. In contrast, in areas that have been developed by humans where the natural resiliency of ecosystems has been lost, floods can be very destructive.
They can destroy homes and other infrastructure, and can lead to a loss of crops, to the spread of waterborne diseasesand to a loss of human life.
Floods can what cause floods to happen disrupt industry, water supplies, wastewater treatment, transport, education, and healthcare, essentially forcing many local economic activities to be halted until rebuilding has occurred .
Floods can be caused by a breaking or failure of infrastructure that can cause large quantities of water to flood a local area. One example is when water mains break such as the one that occurred in July of on the UCLA campus in the United States that caused water to gush out into the surrounding area at 75, gallons per minute.
Another example is when dams break due to faulty construction or maintenance, or when they are overwhelmed due to heavy precipitation. The development and building of infrastructure in flood-prone areas, such as along rivers, near ocean shorelines, or near river deltas, has led to an increase in vulnerability to flooding because the natural resiliency of these ecosystems has been compromised. When deforestation how to make iced tea without ice in a particular area, there are no more trees to help soak up precipitation and reduce waterflow over the landscape.
Without these natural protections, there is an increased risk of flooding and erosion whenever it rains. In developed areas, such as in urban areasthere is commonly a large amount of impermeable surfaces like roads and other concrete structures that do not allow water to permeate back into the soil. When large amounts of rain falls on these impermeable surfaces, the water can accumulate and lead to flooding in low-lying areas if it is not directed properly. Flood embankments that are intended to increase the water-holding capacity of rivers can potentially prevent flood water from draining back into the rivers during large precipitation events .
Among many other climate change impactssome regions are now experiencing increased precipitation and flooding. While we as humans have certainly altered much of the natural how to thin down your legs of the planet, leading to an increase of floods, we can also help to reduce the risks of flooding.
It says the two times. Greentumble was founded in the summer of by us, Sara and Ovi. We are a couple of environmentalists who seek inspiration for life in simple values based on our love for nature. Our goal is to inspire people to change their attitudes and behaviors toward a more sustainable life. Read more about us. While heavy machinery keeps spraying monocrops with pesticides and fertilizersmillions of family farmers are applying agroecological approaches to redress those impacts and revive rural areas.
What is the key to their success? What Are the Human Causes of Floods? Greentumble Environmental Issues March 7, These flooding risks are predicted to increase if greenhouse gas emissions continue unabated. Was this article helpful? We are working hard to improve our content. Let us know if you liked this article. Yes No About Greentumble Greentumble was founded in the summer of by us, Sara and Ovi.
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Apr 04, · A flood occurs when water inundates land that's normally dry, which can happen in a multitude of ways. Excessive rain, a ruptured dam or levee, rapid melting of snow or ice, or even an Author: Christina Nunez. Nov 25, · Here we investigate what causes floods. One area might receive a lot of rain and won’t flood while in other areas the same amount of rainfall can wreak havoc, destroying homes, businesses and the natural environment. Take the Boxing Day floods of , for healthgrabber.usted Reading Time: 3 mins. Most flash flooding is caused by slow-moving thunderstorms, thunderstorms repeatedly moving over the same area, or heavy rains from hurricanes and tropical storms. Occasionally, floating debris or ice can accumulate at a natural or man-made obstruction and restrict the flow of water.
Jump to navigation. Floods are the most common and among the most deadly natural disasters in the United States. They have brought destruction to every state and nearly every county, and in many areas they are getting worse.
A flood is the accumulation of water over normally dry land. River Flooding This occurs when a river or stream overflows its natural banks and inundates normally dry land.
Most common in late winter and early spring, river flooding can result from heavy rainfall, rapidly melting snow, or ice jams. According to one study, approximately 41 million U. Coastal Flooding More than 8. Storm surge can produce widespread devastation.
Flash Floods These quick-rising floods are most often caused by heavy rains over a short period usually six hours or less. Flash floods can happen anywhere, although low-lying areas with poor drainage are particularly vulnerable.
Also caused by dam or levee breaks or the sudden overflow of water due to a debris or ice jam, flash floods combine the innate hazards of a flood with speed and unpredictability and are responsible for the greatest number of flood-related fatalities. This happens when rainfall runoff is channeled from roads, parking lots, buildings, and other impervious surfaces to storm drains and sewers that cannot handle the volume. Many factors can go into the making of a flood.
There are weather events heavy or prolonged rains, storm surge, sudden snowmelt , and then there are the human-driven elements, including how we manage our waterways via dams, levees, and reservoirs and the alterations we make to land. Increased urbanization, for example, adds pavement and other impermeable surfaces, alters natural drainage systems, and often leads to more homes being built on floodplains.
In cities, under-maintained infrastructure can lead to urban flooding. More and more, flooding factors are also linked to climate change. Connecting climate change to floods can be a tricky endeavor. Not only do myriad weather- and human-related factors play into whether or not a flood occurs, but limited data on the floods of the past make it difficult to measure them against the climate-driven trends of floods today.
In other words, while our warming world may not induce floods directly, it exacerbates many of the factors that do. Heavier Precipitation A warmer atmosphere holds and subsequently dumps more water. As the country has heated up an average of 1. In the Northeast, the most extreme storms generate approximately 27 percent more moisture than they did a century ago.
Basically, because of global warming, when it rains, it pours more. Such was the finding of a study by the National Oceanic and Atmospheric Administration NOAA examining the record-breaking rainfall that landed on Louisiana in , causing devastating flooding.
The study determined that these rains were at least 40 percent more likely and 10 percent more intense because of climate change. Looking forward, heavy precipitation events are projected to increase along with temperatures through the 21st century, to a level from 50 percent to as much as three times the historical average. This includes extreme weather events known as atmospheric rivers, air currents heavy with water from the tropics, which account for as much as 40 percent of typical snowpack and annual precipitation along the West Coast.
Experts predict they will intensify, bringing as much as 50 percent more heavy rain by the end of this century. Of course, heavier rainfall does not automatically lead to floods, but it increases the potential for them. And even moderate amounts of rainfall can cause serious damage, particularly in places where urban flooding is on the rise.
Meanwhile, in regions where seasonal snowmelt plays a significant role in annual runoff, hotter temperatures can trigger more rain-on-snow events, with warm rains inducing faster and often earlier melting.
This phenomenon is playing out in the western United States, where, according to the IPCC , snowmelt-fed rivers, at least since , have reached peak flow earlier in springtime. The combination of rain and melting snow can aggravate spring flooding as winter and spring soils are typically high in moisture and often still frozen, and therefore less able to absorb snow and rain runoff.
Regions with higher rain-to-snow ratios, such as the Northwest, are expected to see higher streamflow —and higher flood risks. More-Frequent Hurricanes Climate change is increasing the frequency of our strongest storms , a trend expected to continue through this century.
In the Atlantic basin, an 80 percent increase in the frequency of category 4 and 5 hurricanes the most destructive is expected over the next 80 years.
And stronger storms bring greater rains. It was also slow and therefore able to dump more, a result of weakened atmospheric currents from a warmer atmosphere. Virgin Islands in , produced the most rainfall in the area of any weather event since Stronger storms can also produce gustier winds that whip up greater storm surge , which starts as much as eight inches higher than a century ago because of sea level rise.
Storm surge and winds can also increase the destructiveness of waves, causing them to get bigger and penetrate further inland. Our oceans are approximately seven to eight inches higher than they were in with about three of those inches added since alone —a rate of rise per century greater than for any other century in at least the past 2, years.
In addition to amplifying storm surge because the water starts at a higher level, sea level rise increases high-tide flooding , which has doubled in the United States over the past 30 years and is expected to rapidly worsen in the coming decades. According to the Fourth National Climate Assessment , for example, by , Charleston, South Carolina could see as many as tidal floods per year , compared with just 11 in When flooding inundates a home or community, it upends lives and introduces a litany of potential short- and long-term consequences.
The most obvious include loss of life floods cause more than U. And many times, the same homes are repeatedly flooded—more than 30, properties flooded an average of five times each have been covered under the NFIP. And not only has the NFIP been deeply in debt since Hurricane Katrina, but costly major floods are only becoming more common. An NRDC analysis found that in some cases, it would save money for the government to buy flood-damaged properties, demolish them, and not rebuild on the land.
This would also allow families to move somewhere safer and avoid the hardship of additional floods. Flooding also brings contamination and disease. Floodwaters can carry raw sewage , leaked toxic chemicals , and runoff from hazardous waste sites and factory farms.
They can pollute drinking water supplies and cause eye, ear, skin, and gastrointestinal infections. When floodwaters recede, bacteria and mold may remain , increasing rates of respiratory illnesses, such as asthma. Flooding can also contribute to mental health problems , lead to economic loss as in the form of lost business or wages , and uproot whole communities.
And while it is true that floods do not discriminate, affecting anyone in their path regardless of wealth or ethnicity, it is most often lower-income people, the elderly, and minority communities who suffer the greatest impacts. These populations are least likely to have flood insurance , access to transportation during an evacuation, cash on hand, or the ability to relocate. Advance preparation for a flood can save your property or even your life. See FEMA. To stay safe, take these precautions:.
According to FEMA, flooding is a factor in more than 90 percent of disaster-related property damage in the United States, with many homes repeatedly damaged by floods. But actually finding out if a property is flood-prone when house shopping can be difficult.
The other 29 states and Washington, D. Many are outdated; more on that below. A more low-tech option: Introduce yourself to your prospective neighbors and ask them about flooding in the area. For repeatedly flooded homes, relocation may be the best option. But a wide array of measures exist to prevent or reduce flood damage to structures when relocation is not possible. In areas where flooding is a regular occurrence, more drastic retrofits may include raising the entire structure of a house, wet floodproofing which purposely allows water to flow into a structure and then back out , and dry floodproofing the application of coatings and other sealing materials to walls to prevent floodwaters from entering a home.
Administered by FEMA, the National Flood Insurance Program was created by Congress in to provide affordable flood insurance to homeowners, renters, and business owners. It is available in communities that adopt and enforce floodplain management ordinances and building requirements aimed at reducing flood risks.
The NFIP provides critical aid to victims recovering from a flood disaster, but it also incentivizes the rebuilding of homes in flood-prone areas often multiple times by providing little assistance to those who wish to move to higher ground.
Indeed, it is estimated that more than 30, U. This constant cycle of post-flood rebuilding can lock people into a costly and dangerous situation. It also wastes billions of dollars, which in turn threatens the NFIP itself.
Mitigating potential loss from future floods requires knowing where floods are most apt to occur. NFIP relies on these maps to assess flood risk, determine insurance rates, and establish floodplain management standards. When Hurricane Sandy hit in , for example, many of the maps for areas that were flooded had not been updated in nearly 30 years. The flooding that resulted from the storm covered an area 65 percent larger than the flood-vulnerable area identified by FEMA.
Keeping flood maps up to date is critical because flood risks change as land use and other factors change. Floods, for example, become a greater risk when more pavement and other impervious surfaces are built over an area. Instead, they rely on historical data to determine future flood hazard projections. Moderate- to low-risk areas called non-special flood hazard areas are regions with less flood potential though properties in these areas still account for more than 20 percent of NFIP claims.
High-risk areas also known as special flood hazard areas —or simply floodplains are regions with a 1 percent 1 in chance of being inundated by river or stream floodwaters of a certain magnitude in any given year.
The term year flood refers to this, not a flood expected to occur just once every hundred years. But even a 1 in chance of flooding each year equates to about a 1 in 5 chance a home will flood at some point over the life of a year mortgage.
But we can take steps to lessen their devastation. The latter, scrapped by President Trump in , included, among other things, commonsense measures such as requiring FEMA to rebuild flood-damaged public infrastructure police stations, schools, hospitals, and the like to be safer and stronger than their pre-flood incarnations.
A poll showed that the vast majority of Americans support such flood-smart federal measures—and for good reason. Moreover, such measures increase the odds that millions more Americans will stay safe—and dry. Finally, curbing climate change is an important way to avert some of the worst scenarios for sea level rise and escalating flood risks.
As the IPCC has made explicitly clear , limiting global average temperature rise to within 1. And only ambitious climate action can make that happen. The Quinault Indian Nation is one of several Pacific Northwest tribes planning for relocation, among many other climate adaptation strategies.
The planet is sending us an unmistakable signal that we need to wake up and take real action to combat the climate crisis. And this is the decade we need to do it. As climate change brings heavier rains, local officials and developers are managing the deluge of stormwater runoff with some low-tech—and pretty—solutions.
Stronger storms and harsher cold snaps could mean more dramatic ups and downs for lake levels in the future.
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