"We turned and we saw the water flowing up like a large wave.” That’s according to Renee Lusano when she and her friends nearly became the victims of a flash flood on Commando Trail in East Maui recently. Her friend Sean was washed off the top of the waterfall, and the whole party had to quickly climb to higher ground. The water rose quickly, and miraculously nobody died. The group even had a drone camera and captured the entire ordeal (see video at the end of this article). One moment everyone was having a good time. The next they were fighting for their lives. Flash floods are no joke, and as the name implies, they can happen in a flash. That’s why it’s important to know the dangers wherever you are, and to pay heed to warnings. Maui had received a lot of rain just before this incident due to nearby hurricanes, and a flood advisory had been issued. The group continued with their hike, however. You, too, could face a flash flood, no matter where you live, hike, camp, or vacation. One of the best ways to avoid being caught in one is to know your surroundings, weather conditions, and check for local advisories. [caption id="attachment_19056" align="alignright" width="300"] Calgary's Saddledome flooded when the Bow River flooded its banks.[/caption] When it comes to weather, the most common cause of flash flooding is intense rainfall. Depending on the condition of the ground, this water could start flooding almost instantly. Soft ground like sand and good soil can hold more water, whereas clay and wilt don’t absorb water as well, so it starts flooding much faster after the rain starts falling. The depth of bedrock also plays a factor in flash flooding. The closer the bedrock is to the surface, the faster it will flood. This is because there’s just not as much room for water to soak in to the soil as there would be if the bedrock were much further down. More soil, more saturation, less flooding. Urbanization and fire are also huge factors in flash flooding. Obviously, water can’t permeate concrete very well, so the more roads and sidewalks the water reaches, the greater chance of a flood. Wildfires can change the way the soil takes in water, essentially making it hydrophobic. This means that the ground repels water rather than taking it in. So in places like California or Washington that have had some extended wildfires, there could be some even greater risks for flash flooding (except maybe in California, because the rain doesn’t seem to go there much, anyway). With colder weather on approach, hard and freezing ground can also pose a problem for saturation. If the ground starts freezing and then receives a lot of rain or fast-melting snow, be prepared for some flash flooding. To sum up, heavy rainfall and its inability to soak into the ground can cause massive flooding in an instant. Check out your surroundings where you live and plan accordingly. And in case you forgot, here’s the video of the hikers’ near-death experience with a flash flood: What risks of flash flooding do you see near your home?