It’s pouring outside and you’re stuck in your home. The rain is so heavy that you can’t see what is happening on the street. You start to hear what sounds like thunder, but it only lasts for a few seconds before everything goes quiet again. What is a flash flood and what are you supposed to do?
It is important to know what to do during a flash flood to stay safe. For the sake of this blog post we will be discussing what steps you can take when you experience a flash flood and what safety precautions you should take after the storm has passed.
What is a Flash Flood and What Causes it?
The term “Flash” refers to the fact that these floods are very short lived – usually lasting only a few minutes to an hour. The term “flood” refers to the volume of water involved in such events.
A flash flood is a pluvial flood that typically occurs when rain falls so rapidly that it cannot soak into the ground before reaching streams and rivers. This causes them to rise quickly and carry away everything they touch. In some cases, this may include people who have been caught out on roads without warning signs and can occur within minutes.
Flash Flood vs Flood
Unlike a flood, a flash flood doesn’t involve the movement of huge amounts of water across land. Instead, it involves small quantities of fast flowing water moving down hillsides and ravines, normally due to heavy rain. These flows tend to move slowly and don’t normally reach river level. However, sometimes even a small rise in stream beds can lead to a rapid increase in the downstream flow rate.
Are Flash Floods Common?
In most parts of America, flash floods are relatively common occurrence and can happen at any time during heavy rainfall. It often happens after thunderstorms or tropical cyclones but can also occur in other circumstances such as if a dam has failed.
Flash floods occur more frequently where there is little vegetation because the soil does not absorb much water. It also tends to be worse if the land has recently been cleared for farming. Urban areas tend to be prone to flooding in short time.
Are Flash Floods Dangerous?
Flash floods can be very dangerous! In fact, they are the leading cause of weather related deaths in the United States, with approximately 200 per year. Over half of these deaths are vehicle related.
How to Prepare Your Home For a Flash Flood
You can reduce the chance of being affected by a flash flood by taking steps to make your home less vulnerable to flooding. These measures include:
- Installing a sump pump – They pump excess water away from foundations and basements. They work best when installed near the lowest point in your basement.
- Raising floors above grade level – Floors raised above grade level allow water to drain away rather than pooling against foundation walls.
- Clearing vegetation close to building structures – Trees growing within 10 feet of buildings increase their chances of breaking under pressure from strong winds and falling objects. Trimming shrubs and bushes reduces the amount of surface area available for water runoff. It is also smart to plant wind resistant trees.
- Maintaining drainage systems – Drainage pipes must be kept clean and unclogged. Pipes leading to catchment tanks should be emptied every few years. Catchments collect rainfall and channel it towards sewers via underground pipe networks.
- Purchase flood insurance or renew your flood insurance policy. Most homeowner’s insurance policies do not cover flooding, so it’s best to make sure you are protected before a flood.
What to do During a Flash Flood Watch
In the case of a flash flood watch, you should begin to prepare for the potential of flooding. A flash flood watch means that conditions are favorable for a flood to occur. Here we provide steps you can take to be prepared for a flash flood watch.
- Check your property regularly. If you see any sign of rising water, get out immediately. Don’t wait until the last minute!
- Assemble disaster supplies including a flashlight and extra batteries.
- Placing sandbags along exterior walls – Sandbags placed along external wall surfaces act like dams holding back flood waters.
- Secure or store loose items in your yard, including patio furniture.
- Move valuable objects to higher levels of your home.
- Disconnect electrical appliances, however, do not touch them if you are wet.
What to do During a Flash Flood Warning
If the National Weather Service or your local weather station has issued a flash flood warning, you should take immediate action to protect yourself, your family, and your home from flood damage. A flash flood warning means that flooding is occurring or will imminently occur in the area.
During a flash flood warning, stay indoors with doors closed and keep away from outside walls and high places. Turn off electrical appliances and gas supplies. Do not use elevators unless they are absolutely essential. Avoid driving through flooded areas and prepare for heavy rains.
If you are outside, move to high grounds and stay away from rivers, creeks, streams, and storm drains. Moving water even a few inches deep can sweep you off your feet. If you are driving, stay off of bridges that are above fast-moving water. The overflow of water onto land is an extreme risk, especially when you are stuck outdoors.
When a flash flood warning has ended, check local news reports and listen to radio stations for more information about what happened.
What to do After a Flash Flood
After a flash flood has occurred, it is important that you call your insurance company and report what happened and the damage. Be careful with electrical equipment and make sure it is checked and dry before returning to use. If you experienced a flash flood, contact a water damage expert, like Jenkins Restorations, to determine what needs to be done next.
How Long Do Flash Floods Last?
Flash floods are dynamic and rapid events, making it challenging to pinpoint a specific duration. These floods can occur within minutes to hours of intense rainfall or sudden water release, typically associated with storms or natural disasters. The duration of a flash flood depends on various factors, including the intensity and duration of rainfall, topography, urbanization, soil saturation, and watershed characteristics.
A short burst of heavy rainfall in an area with steep slopes or poor drainage might lead to a swift onset of flash flooding, which could recede relatively quickly if the rain diminishes. However, the unpredictability and complexity of flash floods mean that their duration can range from minutes to several hours, emphasizing the importance of staying vigilant, informed, and responsive to warnings in flood-prone regions.
Frequently Asked Questions
What percentage of flash flood fatalities occur in vehicles?
According to the National Weather Service, about half of all flash flood deaths occur in vehicles.
How many flash floods occur a year?
Flash floods are common in the United States, with an average of about 1,000 occurring each year.
What time of year do flash floods occur?
Floods can happen at any time of the year. However, many flash flood events occur seasonally after winter snows melt or when heavy spring rains occur.
