Meteorological drought

Topic: Natural Hazards and Disaster Management in India · NCERT: Class 11, Ch 6 "Natural Hazards and Disasters: Causes, Consequences and Management"

Meaning

Meteorological drought is a long period when rain is too little and is badly spread over the season. The India Meteorological Department (IMD) counts it when seasonal rain is more than 25% below normal. It matters because it is the first stage of every drought: when the rain fails, soil, crops, rivers and ecosystems run short of water one after another.

Explanation

How it forms (cause → process → result)

• Cause: the monsoon is unreliable.
• In some years the rain comes late, stops early or has long breaks.

• The total rain falls short, or it falls at the wrong time in the season.

• Process: two problems together.

• Too little rain: less water reaches the land than normal.
• Bad distribution: even fair total rain can come in a few heavy spells, with long dry gaps in between.

• High evaporation (heat turning surface water into vapour) makes the shortage worse.

• Result: other droughts follow.

• Meteorological drought is defined by rain alone. It is the starting point.
• If it lasts, it turns into agricultural, then hydrological, then ecological drought.

How IMD grades it

Seasonal rain below normal	Category
More than 25%	Meteorological drought
26-50%	Moderate drought
More than 50%	Severe drought

• Slow-onset hazard: it builds up over weeks and months. It does not strike suddenly like a cyclone or an earthquake.

Its place in the drought chain

• First the rain fails: meteorological drought.
• Then the soil dries and crops wilt: agricultural drought.
• Then, over months, rivers, tanks and wells run low: hydrological drought.
• Finally forests, grasslands and wetlands suffer: ecological drought.

How it is measured for drought declaration

• The Manual for Drought Management (2016, updated 2020) uses rain data as its mandatory indicators (Trigger-1) [2]:
• rainfall deviation (how far rain is from normal, in %), or SPI (Standardised Precipitation Index: a score showing how unusual the rain is compared with past rain) [2]

• plus a dry spell: usually 4 weeks with little or no rain, 3 weeks on light soils and 2 weeks on sandy soils [2]

• IMD supplies the rainfall data [2].

• Rain data alone is not enough. The state must also check any 3 of 4 impact indicators (Trigger-2): crop situation, remote-sensing vegetation indices, soil-moisture indices and hydrological indices [2].
• Early warning: IMD's long-range forecast of 13 April 2026 expected below-normal monsoon rain (90-95% of LPA, the Long Period Average) and a likely El Niño (warming of the central and eastern Pacific that tends to weaken the Indian monsoon) [2].

Where it occurs

• Scale in India (NCERT):
• about 19% of the area and 12% of the people are hit by drought every year

• about 30% of the area is drought-prone, affecting about 50 million people

• Rain-shadow regions: the dry side of a mountain, away from the moist wind.

• The Western Ghats take most of the south-west monsoon rain, so the interior Deccan stays dry.

• Marathwada (central Maharashtra) has drought again and again because it lies in this rain shadow.

• Monsoon margins: places at the outer edge of the monsoon's reach.

• Rajasthan and Gujarat get low and very uncertain rain.

• Jaisalmer and Barmer (west of the Aravalis) get under 90 mm of rain a year. They are in the extreme drought zone, with the Marusthali (Thar desert) and Kachchh.

• Bundelkhand (southern Uttar Pradesh and northern Madhya Pradesh): uncertain rain, hard rock base and thin soils, so drought returns again and again.

• Severe zone (NCERT Fig. 6.7): eastern Rajasthan, most of Madhya Pradesh, eastern Maharashtra, interior Andhra Pradesh and the Karnataka plateau, northern interior Tamil Nadu, southern Jharkhand, interior Odisha.
• Moderate zone: northern Rajasthan, Haryana, southern Uttar Pradesh, the rest of Gujarat, Maharashtra except Konkan, Jharkhand, the Coimbatore plateau (Tamil Nadu), interior Karnataka.

Don't confuse with

• Agricultural drought: the shortage is of soil moisture, so crops fail. Meteorological drought is a shortage of rain only and comes first.
• Hydrological drought: water in aquifers, lakes and reservoirs falls below what rain can refill. It comes after meteorological drought, not at the same time.
• Ecological drought: a natural ecosystem stops being productive because of water stress. It can last after the rain returns. Meteorological drought ends when the rain returns.
• Aridity (a desert climate): always low rain, as in the Thar. Meteorological drought means rain is below the normal for that place. So even a wet region can have one.

Prelims Hooks

• IMD: seasonal rain more than 25% below normal = meteorological drought. 26-50% = moderate; more than 50% = severe.
• Order of droughts: meteorological → agricultural → hydrological → ecological.
• Trap: hydrological drought comes after meteorological drought, not at the same time.
• Drought Manual: rainfall deviation or SPI, plus a dry spell, are the mandatory indicators. The dry spell is 4 weeks normally, 3 weeks on light soils and 2 weeks on sandy soils [2].
• Jaisalmer and Barmer get under 90 mm of rain a year and lie in the extreme drought zone, west of the Aravalis.
• Marathwada is drought-prone because it lies in the rain shadow of the Western Ghats.

Mains Points

• Why meteorological drought is so common in India (GS-I):
• the monsoon is uncertain, and the rain-shadow interior (Marathwada) and the monsoon margins (Rajasthan, Gujarat) are dry
• groundwater is pumped out faster than rain refills it

• so a short rain shortage quickly turns into a hydrological drought, mainly in Marathwada, Bundelkhand and Rajasthan

• From relief to risk reduction (GS-III, Sendai Framework 2015-2030):

• the 2016/2020 Drought Manual adds satellite, soil-moisture and hydrology checks to the rain data
• this makes drought declarations faster and fairer, and links relief money to the NDRF or SDRF [2]

• IMD's long-range forecasts let states plan early, for example by setting aside 5-10% of RKVY flexi-funds for a bad monsoon [2]

• Reducing the impact of a rain shortfall (GS-III):

• rainwater harvesting and watershed development under Jal Shakti Abhiyan: Catch the Rain [3]
• drought-resistant crops, and MGNREGS work to stop distress migration
• river interlinking, which needs a careful check of its ecological and legal costs

Related concepts

• Drought
• Agricultural drought
• Hydrological drought
• Ecological drought
• Drought-prone areas of India
• Akal, trinkal, jalkal and trikal
• Drought mitigation

Read more

• Droughts: types, drought-prone India and mitigation