Mehta et al. (2025) Rainfall temporal variability and drought analysis by means of the Standardized Precipitation Index in Ganganagar District, Rajasthan, India

Identification

• Journal: Frontiers in Climate
• Year: 2025
• Date: 2025-12-01
• Authors: Darshan Mehta, Tommaso Caloiero, S. M. Yadav, Vikram Kumar
• DOI: 10.3389/fclim.2025.1702356

Research Groups

• Department of Civil Engineering, Dr. S. & S. S. Ghandhy Government Engineering College, Surat, Gujarat, India
• National Research Council of Italy–Research Institute for Geo-Hydrological Protection (CNR-IRPI), Rende, Italy
• Department of Civil Engineering, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, India
• Bihar Mausam Sewa Kendra, Planning & Development, Government of Bihar, Patna, India

Short Summary

This study investigated the temporal behavior and severity of droughts in the Ganganagar district of Rajasthan, India, using a 122-year record of monthly precipitation analyzed through the Standardized Precipitation Index (SPI) at multiple timescales. The analysis revealed increasing pre-monsoon wetness and post-monsoon dryness, with frequent drought events, highlighting complex seasonal shifts and persistent hydrological risks.

Objective

• To investigate the temporal behavior, frequency, severity, and long-term variability of droughts in the Ganganagar district, Rajasthan, India, using the Standardized Precipitation Index (SPI) at multiple timescales and trend analysis on a 122-year precipitation record.
• To provide a localized drought characterization for improved agricultural planning, irrigation management, and drought early warning systems in a unique hydro-climatic setting.

Study Configuration

• Spatial Scale: Ganganagar district (Sri Ganganagar), Rajasthan, India, covering an area of 11,154 square kilometers.
• Temporal Scale: 122 years (1901–2022).

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI) at 3-, 6-, 9-, and 12-month timescales.
  • Mann–Kendall test (non-parametric test for trend detection).
  • Simple linear regression (for trend magnitude).
  • Innovative Trend Analysis (ITA) method.
  • Gamma distribution (for SPI calculation).
• Data sources: 122 years (1901–2022) of monthly precipitation data from 54 stations managed by the India Meteorological Department (IMD) of the Ganganagar district, Rajasthan.

Main Results

• Rainfall Trends: A statistically significant increasing trend was observed in May precipitation (+1.1 mm/decade, approximately 12% increase from the monthly average), while December showed a significant decreasing trend (−0.3 mm/decade, approximately 9% decrease from the monthly average). Annual rainfall trends were nearly stable.
• Innovative Trend Analysis (ITA): The Pre-Monsoon and Post-Monsoon seasons showed a clear upward trend in precipitation, indicating wetter conditions in the later period (1962–2022) compared to the earlier period (1901–1961).
• Drought Frequency and Severity (SPI):
  • A total of 66 drought years were identified using the 3-month SPI (30 moderately dry, 16 severely dry, 20 extremely dry).
  • The 6-month SPI identified 32 drought years (15 moderately dry, 8 severely dry, 9 extremely dry).
  • The 9-month SPI identified 17 drought years (4 moderately dry, 9 severely dry, 4 extremely dry).
  • The 12-month SPI identified 18 drought years (8 moderately dry, 5 severely dry, 5 extremely dry).
• Notable Drought Periods: The longest drought event lasted 21 months between 2000 and 2002. Other peak drought years included 1918, 1972/1973, 1987, 2002, 2009, and 2014. The frequency of extreme drought events increased notably after the 1970s.
• SPI Trends: A significant decreasing trend was observed in the 3-month SPI for November (−0.27 SPI/decade), indicating increasing dryness in the post-monsoon season. Conversely, a slight but significant increasing trend was found in the 3-month SPI for May (0.08 SPI/decade), suggesting improving pre-monsoon moisture conditions.

Contributions

• Provides one of the longest district-scale drought analyses (122 years) in semi-arid India, addressing a critical gap in localized drought assessment often obscured by broader regional studies.
• Offers detailed insights into the frequency, severity, and temporal variability of drought events within the Ganganagar district, a unique transitional desert–irrigated zone.
• Establishes a scientific basis for developing district-level drought early warning systems, optimizing irrigation scheduling, and formulating climate-resilient policy interventions tailored to local conditions.
• Highlights a complex pattern of climatic shifts in the region, characterized by an emerging pre-monsoon wetting trend and a persistent post-monsoon drying signal, crucial for integrated water resource management.

Funding

The authors declare that no financial support was received for the research and/or publication of this article.

Citation

@article{Mehta2025Rainfall,
  author = {Mehta, Darshan and Caloiero, Tommaso and Yadav, S. M. and Kumar, Vikram},
  title = {Rainfall temporal variability and drought analysis by means of the Standardized Precipitation Index in Ganganagar District, Rajasthan, India},
  journal = {Frontiers in Climate},
  year = {2025},
  doi = {10.3389/fclim.2025.1702356},
  url = {https://doi.org/10.3389/fclim.2025.1702356}
}