Types of Droughts

Drought is not simply a shortage of rain. It is a condition of water deficit that takes different forms depending on what is being deprived of water — the atmosphere, the soil, the stored reserves, or the natural ecosystem. The book classifies droughts into four distinct types, each defined by its own trigger and its own consequence.

Meteorological Drought is the starting point. It occurs when there is a prolonged period of inadequate rainfall, and crucially, the rainfall that does come is poorly distributed over both time and space. So it is not just about how much it rains, but when and where it rains. A region can receive its seasonal total and still face a meteorological drought if the rain arrives late, ends early, or falls unevenly across the district.

Agricultural Drought, also called soil moisture drought, is the direct fallout on farming. It is characterised by low soil moisture — the water in the soil falls below the level needed to support crops, and the result is crop failure. The book adds an important qualification here: if an area has more than 30 per cent of its gross cropped area under irrigation, that area is excluded from the drought-prone category. The logic is that irrigation provides a buffer against rainfall failure, so such areas are not considered vulnerable to agricultural drought in the same way.

Hydrological Drought operates at the scale of water storage. It results when the availability of water in different storages and reservoirs — aquifers, lakes, reservoirs, and similar bodies — falls below what precipitation can replenish. In other words, the water being drawn out exceeds what the rains can put back in. This is a slower, more cumulative form of drought, because it reflects the balance between recharge and withdrawal over time.

Ecological Drought is the broadest category. It occurs when the productivity of a natural ecosystem fails due to a shortage of water. As a consequence of this ecological distress, damages are induced in the ecosystem itself — the system is not just dry, it is functionally harmed. This goes beyond crops and reservoirs to forests, grasslands, wetlands, and the services they provide.

The book closes with a sobering observation: various parts of India experience these droughts recurrently, and the repeated occurrence results in serious socio-economic and ecological problems. The four types are not isolated — a meteorological drought often cascades into an agricultural drought, then a hydrological one, and finally an ecological one — but each type has its own defining feature and its own threshold of impact.

| Type | Defining feature | Key consequence |

|---|---|---| …