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What are Flash Floods?
Flash floods are the most dangerous kind of floods because they combine the destructive power of a flood with incredible speed. When the amount of severe rainfall surpasses the soil’s capacity to absorb it, flash floods happen. They also happen when water fills typically dry creeks or streams or when enough water builds up for streams to overflow their banks, leading to quick elevations in water levels.
Sikkim Flash Flood: Latest Update
On October 4th, a devastating flash flood hit North Sikkim, triggered by a cloud burst over Lhonak Lake. The Tessta River surged, submerging 41 vehicles and leaving 30 Army personnel missing. The Border Road Organisation (BRO) initiated rescue efforts.
- The situation worsened as water from the Chungthang dam was released, causing a sudden surge downstream, destroying the Indreni steel bridge in Singtam and cutting off Gangtok from the main highway.
- Chief Minister PS Tamang expressed support for the victims and their families.
- Flood alerts were issued in North Bengal and Bangladesh. The Indian Meteorological Department warned of potential landslides and flight disruptions due to heavy rainfall in Sikkim.
- As rescue efforts persist, the region grapples with the aftermath, highlighting the need for preparedness and cooperation in such disasters.
What is a Flood?
Flooding is the overflow of water onto typically dry ground. Floods can occur as a result of strong rains, incoming waves from the ocean, rapid snowmelt, or the failure of dams or levees. Even a few inches of water can cause destructive floods, or the water can reach a house’s roof. Floods can happen suddenly or gradually over a long period of time, lasting for days, weeks, or even longer. Of all weather-related natural disasters, floods are the most prevalent and extensive.
Flash floods are defined as floods that occur within six hours of severe rainfall or for another cause. Flash floods, however, can occasionally happen minutes or a few hours after a heavy downpour. They are basically quick flooding of low-lying places, such as washes, rivers, dry lakes, and depressions, known as flash floods. Flash floods are more dangerous than typical floods in terms of potential damage due to their unpredictable nature and brief duration.
Causes of Flash Flood
Flash floods are most common in arid places that have just received precipitation, although they can occur anyplace downstream from the origin of the precipitation, even many kilometres away. The causes of Flash floods are mentioned below:
- In just four months (June to September), about 75% of the total rainfall falls; during these months, rivers have a tremendous discharge.
- It could be brought on by a hurricane, a tropical cyclone, a violent thunderstorm, or meltwater from ice or snow running over ice sheets or snowfields.
- Flash floods can also happen as a result of levee or dam breaks, mudslides, or debris flows.
- Flash floods have also happened following eruptions in locations on or close to volcanoes when glaciers melted from the extreme heat.
- The intensity of the precipitation, location and distribution of the precipitation, terrain and land use, vegetation kinds and growth/density, soil type, and soil water content all affect where and how quickly the flash flooding may occur.
- Orissa, West Bengal, and Andhra Pradesh’s coastal regions experienced depressions and cyclonic storms.
- The frequency/number of the aforementioned phenomena has grown due to climate change and global warming.
- Wildfires may be followed by the onset of flash floods. Forests and other types of vegetation are destroyed by wildfires, which weaken the soil and reduce its ability to allow water to permeate.
Effects of Flash Floods
Due to the sudden onset and quick water movement of flash floods, they are particularly hazardous. Though it provides little to no protection from being washed away, having a car can make people overconfident and less likely to avoid flash floods. More than half of the fatalities associated with flash floods involve motorists who are swept away in their vehicles while attempting to cross flooded intersections. The majority of SUV-sized vehicles can be carried away by just 2 feet (0.61 m) of water. The effects of Flash Floods are:
- It has an effect on the natural environment, including pollution, agriculture, vegetation, and geomorphology.
- The human population is affected (entrapments, injuries, fatalities).
- Among other classes of floods (such as riverine and coastal), they also have the highest mortality rate (measured as the number of deaths per many people impacted).
- With more than 5,000 lives lost each year, flash floods are among the deadliest natural disasters in the world. They also have a substantial negative impact on society, the economy, and the environment.