Aridity Anomaly Outlook Index

Aridity Anomaly Outlook Index

News: Recently, Indian Meteorological Department (IMD) has released the Aridity Anomaly Outlook (AAO) Index of July 2022, which says at least 85% of districts face arid conditions across India.

About:
• The index monitors agricultural drought, a situation when rainfall and soil moisture are inadequate to support healthy crop growth till maturity, causing crop stress.
• An anomaly from the normal value signifies a water shortage in these districts that could directly impact agricultural activity.

How is the index prepared?
• A real-time drought index in which water balance is considered.
• The Aridity Index (AI) is computed for weekly or two-week periods.
• For each period, the actual aridity for the period is compared to the normal aridity for that period.
• Negative values indicate a surplus of moisture while positive values indicate moisture stress.

What are the Findings?
• Only 63 of 756 districts are non-arid, while 660 are facing different degrees of aridity — mild, moderate and severe.
• Some 196 districts are in the grip of a ‘severe’ degree of dryness and 65 of these are in Uttar Pradesh (highest). Bihar had the second highest number of districts (33) experiencing arid conditions. The state also has a high rainfall deficit of 45%.
• Other districts facing ‘severe arid’ conditions are Jharkhand, Haryana, Madhya Pradesh, Delhi, Telangana, Maharashtra, Andhra Pradesh, Jammu and Kashmir, Punjab, West Bengal, Rajasthan, Karnataka and Tamil Nadu.
• The SPI on the DEWS platform also highlights a persisting rainfall deficit in these areas in the last six months.
• Arid conditions have impacted the ongoing kharif sowing, as the area sown under different kharif crops as of July, 2022, was less by 13.26 million hectares compared to the corresponding period in 2021.

What is SPI?
• The Standard Precipitation Index (SPI) is a widely used index to characterize meteorological drought on a range of timescales. On short timescales, the SPI is closely related to soil moisture, while at longer timescales, the SPI can be related to groundwater and reservoir storage.
• The SPI on the Drought Early Warning System (DEWS), a real-time drought monitoring platform managed by the Indian Institute of Technology, Gandhinagar (IIT-G) platform highlights a persisting rainfall deficit in these areas in the last six months.
• UP, Jharkhand, Bihar, West Bengal and some parts of the North East are under extreme drought situation and agriculture of these regions might be affected.