Kumar et al. (2025) Spatiotemporal analysis and mechanisms of drought flood abrupt alternation events in India

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-27
• Authors: Aman Kumar, Dhyan Singh Arya
• DOI: 10.1016/j.ejrh.2025.102992

Research Groups

• Department of Hydrology, Indian Institute of Technology Roorkee, India

Short Summary

This study comprehensively analyzes the spatiotemporal patterns, characteristics, and teleconnection drivers of Drought-Flood Abrupt Alternation (DFAA) events across India from 1901 to 2022, identifying key hotspots and an increasing trend in rapid drought-to-flood transitions influenced by ENSO, NAO, and IOD.

Objective

• Identification of DFAA events and their characteristics (duration, frequency, intensity).
• Localization of DFAA hotspots in India and determination of significant transition months.
• Investigation of potential driving forces (teleconnections) behind DFAA events.

Study Configuration

• Spatial Scale: Indian landmass (6°N–38°N, 65°E–100°E), covering 3,287,263 square kilometres, analyzed at 0.25° x 0.25° spatial resolution across 8 Köppen climate zones.
• Temporal Scale: Daily data from 1901 to 2022 (122 years) for precipitation and temperature; monthly teleconnection indices from 1951 to 2022.

Methodology and Data

• Models used:
  • Standardised Weighted Average Precipitation (SWAP) index for daily drought and flood quantification.
  • Run theory for identifying drought and flood events, including their start/end dates, duration, magnitude, and intensity.
  • Continuous Wavelet Transform (CWT) for dominant frequency analysis of DFAA events and teleconnections.
  • Cross Wavelet Transform (XWT) for assessing correlations between DFAA events and climate indices.
  • Improved Partial Wavelet Coherence (IPWC) for isolating individual contributions of climate indices (ENSO, IOD, NAO) to DFAA transitions.
• Data sources:
  • Daily gridded precipitation and temperature data from the Indian Meteorological Department (IMD) for 4964 grid stations (1901-2022).
  • Nino3.4 index (Sea Surface Temperature anomalies).
  • Indian Ocean Dipole (IOD) index (Sea Surface Temperature anomalies difference).
  • North Atlantic Oscillation (NAO) index (surface sea-level pressure difference).
  • Teleconnection indices obtained from http:www.ncdc.noaa.gov/teleconnections/ao.php.

Main Results

• Hotspots: Gujarat, adjacent areas of Rajasthan, and northeastern states (Manipur, Tripura, parts of Assam and Mizoram) are identified as major DFAA hotspots, experiencing over one abrupt shift per year. Central Jammu & Kashmir, Himachal Pradesh, and Uttarakhand show high flood-to-drought (FTD) frequency.
• Temporal Patterns: Drought-to-flood (DTF) transitions peak at the start of the monsoon (May and June), while FTD transitions are most common during the monsoon retreat (October and November). Winter monsoon DTF transitions occur in December and January in northern India.
• Duration and Intensity: FTD events have a longer average duration (165 days) compared to DTF events (130 days). DTF transitions are more abrupt, with a higher average transition rate (Kmax = 2.03) than FTD (Kmax = 1.44). An increasing trend in rapid DTF transition events is observed across most climatic zones.
• Teleconnections:
  • ENSO (NINO3.4): Exhibits a strong 3–5-year anti-phase link with DFAA event occurrence across most climate zones, indicating reduced transition activity during warm ENSO phases.
  • NAO: Shows growing decadal influence in specific regions (Am, CWa, Cwb) and staggered 1–3 year periodicity in the Upper Himalayas (Bk, D zones).
  • IOD: Displays an increasing influence after 2000, with significant 3–4 year correlations observed between 1992 and 1998 in several zones.
  • IPWC analysis indicates NINO and NAO are primary drivers, with IOD playing a smaller, supporting role, and positive NAO/IOD effects tending to counteract each other.

Contributions

• Provides the first comprehensive spatiotemporal analysis of Drought-Flood Abrupt Alternation (DFAA) events across India, utilizing a daily-scale index (SWAP) to capture short-duration events.
• Identifies specific hydroclimatic hotspots and critical seasonal timings for DTF and FTD transitions, offering region-specific insights for water resource management.
• Quantifies the frequency, magnitude, duration, and intensity characteristics of DFAA events, revealing that DTF transitions are generally more abrupt.
• Employs advanced wavelet techniques (CWT, XWT, IPWC) to disentangle the complex, scale-dependent influences of major teleconnections (ENSO, NAO, IOD) on DFAA events.
• Explains the underlying physical mechanisms of DFAA formation in India and highlights an increasing trend in rapid DTF transitions, underscoring the need for enhanced forecasting and climate-resilient strategies.
• Suggests the necessity for a new homogeneous classification approach based on DFAA events to improve irrigation, flood, drought, and water quality management.

Funding

• Prime Minister Research Fellowship grant number (PM-31–22–715–414) of the Ministry of Education India.

Citation

@article{Kumar2025Spatiotemporal,
  author = {Kumar, Aman and Arya, Dhyan Singh},
  title = {Spatiotemporal analysis and mechanisms of drought flood abrupt alternation events in India},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102992},
  url = {https://doi.org/10.1016/j.ejrh.2025.102992}
}