What Causes a Flood | What Destructive Floods Need
Many destructive floods happen across the U.S., and much more around the world. Learn more about what causes a flood here…
Floods are one of the most powerful forces of nature out there. A lot of people do not realize just how powerful it is. Like did you know that one cubic yard of water weighs over 1,684 pounds? Crazy, right? We will learn more about what causes a flood, what they do, and destructive examples here.
This post is all about flood causes and their effects.
Damaging Floods
What is a Flood?
According to Oxford Languages, a flood is “an overflowing of a large amount of water beyond its normal confines, especially over what is normally dry land.” Floods are the most common weather-related disasters and are dangerous. The NWS often says “Turn Around, Don’t Drown.” This is saying that when you are in a car, do NOT drive through flood waters, even when it doesn’t look that deep. Water can be way deeper than it seems & just six inches can drag your car away. Floods can happen for many reasons, like heavy rain, fast melting snow, waves crashing against the shore, and dams/levees breaking. We will not talk about the waves crashing against the shore on the beach because that is coastal flooding, and that is for another day.
How Do Floods Form?
Floods form in different ways for different types of floods. The main cause of a flood is excessive rainfall so we will go for that today. So this common scenario occurs in a valley with a town at the bottom, like pictured above. The storms in the vicinity are dumping heavy rain, like 2+ inches an hour, on the town & mountains above. The rainwater from the mountains quickly turns into runoff that takes the fastest way down the mountain. When it meets the water of the city, it is too much and the city starts with inches of water, then a few feet. It turns into a flood disaster, with large objects like cars, poles, and even whole buildings rapidly speeding through the water. People are caught in it, too. This is the scenario for many of the floods in the world. This next section is about the effects of a flood.
What Are the Effects of a Flood?
The effects of a (flash) flood can be widespread and destructive. The impact may vary with the type of flood. This comes back to the introduction when it stated that one cubic yard of water is over 1,684 pounds. So imagine a whole river racing at high speeds around human property. After the initial flood, the ground will be SOAKED. There will also be tons of mud and dirt in the streets and on structures. This is because the water carried all of that into the town. Cars, buildings, and other objects will be scattered all over the place for the same reason. Cleanup crews will start arriving and the same for news crews. Flood insurance companies will have a lot of work. There is also, the mental health impact on the people. It might be hard for them when a storm comes by or there is any precipitation. Seeing all of this and more really shows the damage a flood can produce.
Flood Example – Old Ellicott City Floods
The example flood that I will use will be the Ellicott City, MD Floods from 2016 & 2018. Both floods came from heavy rainfall and had tall, wide, and destructive flows of water running through the streets of the cities. People died in both, there is footage of cars being swept away & people holding on for their lives. For the 2016 Ellicott flood, 6 inches of rain fell in just two hours, which is an incredible amount of rain. The 2018 flood had 8 inches of rain in two hours. 8 inches is over half as tall as a bowling pin! Even though the 2016 event had less rainfall, it resulted in more deaths, with two compared to one. The reason the city floods so much is that it is an old, low-lying city with a bunch of rivers spread out around the city. Now we can see why this happened twice. But still, an occurrence like this is really rare, two 500-year floods happening just two years apart? Wild!
