Last weekend in Nogales, Sonora, three women died as a result of the water currents that swept them away, two of the victims were minors and were traveling with their mother in a taxi when the current swept them away.
An intense storm fell this Saturday afternoon in the municipality of this entity located in the north of the country, which in previous months was affected by droughts. According to the Conagua report of July 29, the percentage of drought was reduced due to the presence of the phenomenon known as monsoon circulation .
“Thus, according to the Drought Monitor in Mexico, as of July 15, the area with some type of drought in Sonora was reduced to 83.1% from the 100% registered on June 15, 2022. In the same period, the number of municipalities with extreme drought decreased from 43 to 14”, .
The presence of this phenomenon of floods occurring after a dry season is reminiscent of the phenomenon known as flash or lightning floods .
What are flash floods?
The explains that flash floods correspond to rapid increases in the water level in streams or streams above the flood level . It is a frequent phenomenon in mountain areas subjected to intense rains or rapid thaws or in normally dry areas.
Although the international body focuses on the European continent, this type of flooding can occur anywhere in the world.
In our country, the National Center for Disaster Prevention (Cenapred) details that flash floods can cause small streams to transform in a matter of minutes into violent torrents capable of causing great damage. They are normally associated with land with a steep slope.
Also, the combination of the following characteristics increase the risk of flash floods:
- Orography of the terrain , particularly in areas with steep slopes, and which determine the speed that the water can reach.
- Vegetation density , which often contributes to reducing the amount of water that flows freely over a surface.
- Failures in hydraulic infrastructures that lead to their breakage.
- Soil absorption capacity , which may be saturated by previous rainfall. In relation to this condition, the waterproofing effect that forest fires usually generate or the presence of non-porous pavements that facilitate runoff deserves a special mention.
What are the areas most at risk of flooding?
At the national level, the lowlands and coastal areas are the ones that are most affected.