India's monsoon paradox: How droughts triggered by El Nino make flash floods deadlier

India has flagged 197 districts as highly vulnerable to El Nino. Here is why drought-baked ground and sudden cloudbursts are a deadlier combination than the headline numbers suggest.

In Short

• El Nino weakens India's monsoon, baking topsoil until it repels water.
• Parched, cracked Earth cannot absorb rain, turning localised cloudbursts into flash floods.
• India has flagged 197 districts as highly vulnerable to El Nino this season.

There is a particular cruelty to the way drought and flood arrive together in India.

The rain has not come for weeks. The Sun bakes the Earth until it cracks. Farmers scan cloudless skies. Officials flag districts. And then, without warning, the sky opens in a single, violent hour and the water, instead of soaking into the ground, runs off a surface as hard as a road, flattening everything in its path.

This is not a paradox. This is physics.

Union Agriculture Minister Shivraj Singh Chouhan has flagged 197 districts across India as highly vulnerable to El Nino this season. The national rainfall forecast sits at 90 per cent of the Long Period Average, or LPA.

The LPA is simply the average rainfall India receives over a 50-year baseline period, a standard yardstick meteorologists use to describe whether a monsoon is normal, deficient, or excess. At 90 per cent, the forecast sounds nearly normal. What it hides is the danger.

THE GROUND THAT FORGOT WATER

El Nino is a periodic warming of the central and eastern tropical Pacific Ocean. When sea surface temperatures there rise by even a fraction of a degree above normal, it reorganises atmospheric circulation patterns across the globe, and in India's case, it typically weakens the monsoon.

A weakened monsoon means weeks of heatwaves rather than rainfall. Those heatwaves do something to soil that most people never think about.

Topsoil, or the thin, dark, living layer at the surface of the Earth, is not simply dirt.

It is a porous medium, which means it is full of tiny air pockets and channels formed by roots, insects, and microorganisms.

Under normal conditions, these channels absorb rainwater relatively quickly, letting it seep downward to replenish groundwater.

But under sustained, intense heat, two things happen. The surface moisture evaporates, shrinking the soil particles. The channels crack and collapse. The living organisms that maintain soil structure die off. And the topsoil, hardened and fractured by weeks of unrelenting sun, becomes nearly impermeable.

Hydrologists call this soil hydrophobicity, the phenomenon in which dried, parched Earth repels water rather than absorbing it.

When a cloudburst then strikes this hardened ground, the water has nowhere to go.

THE CLOUDBURST THAT DOES NOT WARN YOU

A cloudburst is a meteorological term for extremely intense, highly localised rainfall, technically defined as 100 millimetres or more of rain falling within one hour over an area roughly 20 to 30 kilometres wide.

The water hits the ground faster than it can possibly be absorbed. It pools instantly, then runs, gathering speed across hard, cracked surfaces. It pours into drainage channels already clogged by dry sediment. It races into valleys and low-lying areas. It becomes a flash flood in minutes, sometimes in seconds.

This is not a failure of weather forecasting. It is a structural vulnerability of drought-stressed land.

The 197 districts flagged by the government are already carrying this vulnerability. The 90 per cent LPA headline is cold comfort when even a brief, intense spell of rainfall can overwhelm ground that has forgotten how to drink.

The cruel logic of the deluge dividend is this: the drier the land, the more dangerous every drop.

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