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Background <p>Over half of India’s agricultural land relies on rainfall, and changes in drought frequency, duration, and intensity directly impact agricultural productivity and water resources. However, comprehensive evaluations of composite drought hazards across the nation’s agro-climatic zones at specific warming levels are limited.</p> Objective <p>A composite drought hazard index (DHI) was developed for 15 agro-climatic zones in India. This index facilitated a comparison between the reference period of 1995–2014 and three future 20-year windows corresponding to global warming scenarios of 2&#xa0;°C (2041–2060), 3&#xa0;°C (2052–2071), and 4&#xa0;°C (2070–2089).</p> Methods <p>The Standardized Precipitation Evapotranspiration Index (SPEI) was derived from bias-corrected NEX-GDDP-CMIP6 projections of the MPI-ESM1-2-LR model at a spatial resolution of 0.25°. Potential evapotranspiration was calculated using the FAO-56 Penman–Monteith method. The application of run theory facilitated the determination of drought frequency, duration, and intensity, which were subsequently integrated through weighted normalization into a drought hazard index (DHI). This index was categorized into eight quantile-based hazard grades. The analysis was further refined using grade-transition matrices, seasonal aggregation, independent historical validation, and the attribution of precipitation versus potential evapotranspiration.</p> Results <p>The frequency of drought events during the reference period varied between 1.15 and 2.95 events per year, with durations ranging from 1.30 to 3.17&#xa0;months and intensities between 0.90 and 1.23. The highest Drought Hazard Index (DHI) of 0.84 was recorded in the Western Dry Region, Gujarat Plains, and Himalayan zones. At temperature increases of 2&#xa0;°C, 3&#xa0;°C, and 4&#xa0;°C, 56%, 47%, and 60% of India’s land area, respectively, transitioned to a higher hazard grade, with the extreme hazard (Grade VIII) expanding from 0.17% to 10.9% of the national area. New hotspots were identified in the Central Plateau, Eastern Plateau, and Upper Gangetic Plain, areas not typically regarded as drought prone. Amplification was primarily observed in the pre-monsoon period at 2&#xa0;°C and the post-monsoon period at 3&#xa0;°C, with winter drying intensifying again at 4&#xa0;°C. Validation against an independent observed Standardized Precipitation Evapotranspiration Index (SPEI) product demonstrated mixed zonal skills.</p> Conclusions <p>Warming shifts drought hazards across India rather than intensifying them in severely affected regions. Warming-level maps provide a scenario-independent framework for planning and prioritizing water resources. However, these projections should be interpreted as directional estimates from a single model and not as definitive forecasts.</p>

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Assessment of drought hazard change across agro-climatic regions of India under 2 °C, 3 °C and 4 °C warming levels based on CMIP6 projections

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  • 发表日期：

    2026年8月1日

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  • P. Sreelakshmi,
  • Sushant Sawant

摘要

Background

Over half of India’s agricultural land relies on rainfall, and changes in drought frequency, duration, and intensity directly impact agricultural productivity and water resources. However, comprehensive evaluations of composite drought hazards across the nation’s agro-climatic zones at specific warming levels are limited.

Objective

A composite drought hazard index (DHI) was developed for 15 agro-climatic zones in India. This index facilitated a comparison between the reference period of 1995–2014 and three future 20-year windows corresponding to global warming scenarios of 2 °C (2041–2060), 3 °C (2052–2071), and 4 °C (2070–2089).

Methods

The Standardized Precipitation Evapotranspiration Index (SPEI) was derived from bias-corrected NEX-GDDP-CMIP6 projections of the MPI-ESM1-2-LR model at a spatial resolution of 0.25°. Potential evapotranspiration was calculated using the FAO-56 Penman–Monteith method. The application of run theory facilitated the determination of drought frequency, duration, and intensity, which were subsequently integrated through weighted normalization into a drought hazard index (DHI). This index was categorized into eight quantile-based hazard grades. The analysis was further refined using grade-transition matrices, seasonal aggregation, independent historical validation, and the attribution of precipitation versus potential evapotranspiration.

Results

The frequency of drought events during the reference period varied between 1.15 and 2.95 events per year, with durations ranging from 1.30 to 3.17 months and intensities between 0.90 and 1.23. The highest Drought Hazard Index (DHI) of 0.84 was recorded in the Western Dry Region, Gujarat Plains, and Himalayan zones. At temperature increases of 2 °C, 3 °C, and 4 °C, 56%, 47%, and 60% of India’s land area, respectively, transitioned to a higher hazard grade, with the extreme hazard (Grade VIII) expanding from 0.17% to 10.9% of the national area. New hotspots were identified in the Central Plateau, Eastern Plateau, and Upper Gangetic Plain, areas not typically regarded as drought prone. Amplification was primarily observed in the pre-monsoon period at 2 °C and the post-monsoon period at 3 °C, with winter drying intensifying again at 4 °C. Validation against an independent observed Standardized Precipitation Evapotranspiration Index (SPEI) product demonstrated mixed zonal skills.

Conclusions

Warming shifts drought hazards across India rather than intensifying them in severely affected regions. Warming-level maps provide a scenario-independent framework for planning and prioritizing water resources. However, these projections should be interpreted as directional estimates from a single model and not as definitive forecasts.