Floods may not always threaten life, especially if we have swimming skills. However, flash floods, like those recently experienced in the northern mountainous region, occur suddenly and leave little time to react. Regardless, some experiences gathered by many can help realize the slim chance of survival.
Prevention is Better than Cure
This is the first lesson highlighted by disaster researchers in the United States, based on the fundamental characteristic of flash floods, which is their lack of clear warning signs. Often, when flash floods occur, the sky can be cloudless, or it may even have stopped raining.
A driver escapes by jumping from the vehicle during a flash flood in Morocco.
Flash floods are a form of exceptionally large flooding that occurs unexpectedly in rivers and streams in mountainous and hilly areas, lasting for a short period.
The primary cause of flash floods is usually heavy rainfall with high intensity. However, flash floods become particularly dangerous when they occur in watersheds with steep slopes, significantly fragmented terrain that forms gullies, ravines, and areas with sparse vegetation that have been indiscriminately destroyed.
Floods form due to heavy rainfall, causing water levels in rivers and streams to surge, then cascading down to lower areas from above. (Photo: NIWA).
Additionally, watersheds with heavily weathered surfaces and weak structures are more prone to flash floods.
A key characteristic of flash floods is that they carry a large amount of solid material, often mud and rocks, leading to them being referred to as mudslides, which are quite common in our country. Flash floods typically occur at night and early morning, lasting between 3 to 6 hours during flood months.
Moreover, other forms of flash floods can occur, such as dam break floods, blockage floods, and reservoir floods.
Currently, there is no effective flash flood warning system despite the bold claims from scientists.
In a context where one cannot rely heavily on public disaster prevention systems, disaster experts suggest the following experiences to mitigate risks:
- Monitor rainfall not only in your immediate area but also in surrounding regions, especially upstream of rivers and streams.
- Be cautious when there is rain upstream, even if it is not raining where you are, particularly during prolonged rainfall, even if the amount is not significant.
- Be on high alert after widespread heavy rainfall in the watershed where you live, especially if no floods or flash floods have yet occurred.
- If living long-term near rivers or streams, develop a habit of recording rainfall in the area to gain a broader and longer-term view of the risks.
- Consider purchasing disaster insurance and pay attention to the effective date of the insurance policy to ensure you can receive compensation if disaster strikes.
If driving in areas near rivers or mountains, before you go:
- Familiarize yourself with the maps of the canyons, watersheds, and roads that cross rivers and streams.
- Memorize the advice from NOAA (National Oceanic and Atmospheric Administration) to “turn around, don’t drown” if there is any flooding ahead.
Flash flood in Morocco swept a car into a river on September 23, 2014. (Photo: AFP).
When Flash Floods Strike
The survival rate is low when flash floods hit, but awareness can still be beneficial:
- Take deep breaths to overcome panic, reminding yourself that you will survive.
- Run quickly to the highest and most stable location.
- Grab anything that can float on the water’s surface, such as plastic containers, wooden poles, or mats, even if the floodwaters haven’t risen high yet.
- Do not wade through floodwaters, even if they are only 15cm deep. According to NOAA, floodwaters at that depth can knock down even strong individuals, causing fractures, and may push victims into deeper and stronger currents.
- Any location where water reaches just the ankle is dangerous, especially during nighttime disasters when visibility is limited.
- If you cannot escape the flooded area, try to find shallow and slow-moving water.
- Try to carry a sturdy stick to check the water depth and avoid falling into deep holes or tripping over large obstacles.
- Avoid areas with mud or large floating objects that can knock you down, even in shallow currents.
- If swept away by the water, according to Desmond Johnson of the Swift Water Rescue team, hold on tightly or climb onto something nearby if possible. When floating down the current, try to grab onto floating objects instead of going underneath them.
- If you hold onto something, keep your feet pointed downstream, yell loudly, and wave one hand if you can. Johnson states that it is very difficult to spot victims submerged underwater, so try to signal for help continuously until rescued.
A truck in Morocco overturned by a flash flood.
With Vehicles
According to the Federal Emergency Management Agency (FEMA), do not drive through floodwaters, even if they seem shallow. Water just 1 cm deep can float a vehicle if driven quickly enough. Water 15cm deep can affect the vehicle’s undercarriage; 30cm can float a vehicle; and 60cm is enough to sweep a vehicle away.
- If you are in a vehicle and water is rising, escape as quickly as possible. First, unbuckle your seatbelt, lower the window, or use a hard object to break the window, allowing water to rush into the vehicle quickly. Otherwise, a pressure difference of 1,000 kg will make it impossible to open the door.
- Before the vehicle fills with water, take a deep breath, then within 60 seconds, escape through the lowered window or forcefully push the door open.
What are pipe floods? Where and when do they usually occur?
What are flash floods? Where and when do they usually occur?
