What are the signs before a flash flood?

The warning signs before flash floods are as follows:

Pay attention to whether there is turbid well water or sudden muddy water coming out of the ground; whether there are any abnormal reactions of animals and plants, etc., and any obvious If there is a warning sign, you should evacuate the scene quickly and decisively. In addition, flash floods and mudslides start from the top of the ditch. If you hear a roaring sound, you must be vigilant and avoid it in time.

How to escape once you encounter a flash flood:

First of all, pay more attention to weather forecast and warning information during the flood season, try to avoid dangerous areas such as mountainous areas and rivers, and keep abreast of weather changes. , make preparations for home protection and ensure safety.

Secondly, if you travel to mountainous areas or rivers, you should pay attention to the mountain and water conditions, pay attention to flash flood hazard signs and safe evacuation routes, and leave the danger area as soon as possible.

When receiving a warning or encountering a flash flood, do not hesitate or abandon your belongings. Immediately follow the warning information or run to the high slopes on both sides of the ditch. Never run along the ditch.

The causes of flash floods include: terrain conditions, forest coverage conditions, water source conditions, etc.

1. Terrain conditions.

Generally, the terrain characteristics that cause flash floods and debris flows are mid-to-high mountainous areas, with large relative height differences and steep valley slopes. The surface layer is skin grafting covered with thick soil, and underneath the soil is a broken rock layer cut by medium-deep faults and their derived faults.

2. Forest coverage conditions.

With a large area of ??forest and moso bamboo covering, the warm and humid air carries a large amount of water vapor to the sky above the forest area. It collides with the cold air with low temperature and high relative humidity in the forest area, which can easily cause heavy local precipitation.

3. Water source conditions.

Water bodies are both a component and an initiating factor of flash floods and debris flows, mainly from rainfall. During the early rainfall, the soil moisture content on the top of the mountain was saturated, and the water pressure in the lower rock formations increased sharply.

Characteristics of flash floods:

1. Seasonality: April to September every year, especially June to August, is the period when flash floods occur frequently. In the same place, even It is possible for multiple flash floods to occur in succession, which is seasonality.

2. Sudden nature: Mountain streams have poor water storage capacity, large slopes, short processes, and fast flow rates. Therefore, after a flash flood breaks out, it can often hit the downstream in a very short period of time. , leaving no time for people to react along the way.

3. Mass-occurrence: The free surfaces on both sides of the mountainous streams have complex geological structures and collapses often occur. Especially under the impact of floods, large-scale collapses are likely to occur. Mudslides will form.

4. Susceptibility: The development of mountainous areas is relatively backward, and preventive measures against flash flood disasters are insufficient. Therefore, the predictability of flash flood disasters is very low, outbreaks are more frequent, and prevention is extremely difficult.