Opinion Ramban rain causes destruction: Understanding the weather events affecting the region

The Ramban district administration, Udhampur MP and Union Minister Jitendra Singh, and the J&K Office of Chief Minister all posted information about the events on social media, using terms like flash flood, landslide, and cloudburst. What are these events, what causes them, and what impact can they have? We explain.

What is a cloudburst?

While episodes of heavy rain are often termed “cloudburst”, a cloudburst has a specific technical definition — rainfall of 10 cm or more in an hour, over a roughly 10 km x 10 km area.

Cloudbursts are more common in hilly areas because of a phenomenon called ‘orographic lift’, which basically means warm air rising up the side of a mountain. As warm air ‘climbs’ a mountain, it expands because of the low pressure above. The expanding air cools, releasing the moisture it was holding as rain. But if more and more warm air keeps rising, it prevents that rain, till a large amount of rain builds up and bursts out in a massive shower all at once.

Because cloudbursts happen in localised areas ( over a roughly 10 km x 10 km area), they are difficult to capture accurately.

The sudden rain released by a cloudburst can quickly overwhelm drainage systems and lead to flash floods and landslides.

What is a flash flood?

As the name suggests, a flash flood happens quickly, when a lot of rain suddenly enters into the drainage systems (waterbodies, drains), and water overflows. Flash floods are again more common in hills, because rocky terrain does not absorb water very well.

While river floods, the kind normally seen in plains, last longer and cause more damage to property, the sudden flash floods are more likely to lead to loss of life.

What is a landslide?

Landslide is a portion of ‘land’ coming loose and sliding — rocks and soil slipping down a mountain, for example. As the British Geological Survey’s website says, “When the force of gravity acting on a slope exceeds the resisting forces of a slope, the slope will fail and a landslide occurs…adding water to the material on a slope makes a landslide more likely to happen. This is because water adds weight, lowers the strength of the material and reduces friction, making it easier for material to move downslope.”

A lot of water gushing down just speeds up this process. Landslides can crush people and animals under the debris, make roads unmotorable, and a lot of debris falling into a water body can cause floods.