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<p>Under future changing climate conditions, hydro-climate variability is poised to intensify with extreme events surpassing historical thresholds. While the influence of El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on global and regional hydro-climates are well-documented, their specific effects at finer spatial scales remain less explored. This study significantly advances our understanding by establishing a teleconnection between these multifaceted climate oscillations and the Aghanashini River Basin (ARB), a Ramsar wetland site and a part of UNESCO biodiversity hotspot, identifying the vulnerability of this fragile ecosystem to the intensifying impacts of changing climate. Non-parametric biwavelet and multiwavelet analyses revealed significant shared power (95% significance level) between combined ENSO-IOD phases and hydro-climate variables (rainfall, temperature and streamflow) at periodicities exceeding 12&#xa0;months, with an Average Wavelet Coherence Power exceeding 0.70, indicating a stronger combined influence compared to individual oscillations. Positive ENSO-IOD phases increased mean rainfall by 12.76%, leading to extreme wet conditions with water yield ranging from 2.75 × 10<sup>9</sup> to 0.2 × 10<sup>9</sup> m<sup>3</sup> during monsoon months, while negative phases induced droughts. Using the enhanced Soil and Water Assessment Tool (SWAT), the projected increase in the frequency and intensity of consecutive ENSO-IOD events (0–4/31&#xa0;years) are expected to exacerbate hydrological extremes, causing more frequent and severe floods and droughts and significantly altering salinity levels (&gt; 30 ppt) in the ARB river ecosystem. These changes threaten biodiversity and river health, calling for urgent global action through adaptive water management and community-led restoration to ensure long-term sustainability.</p>

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Deciphering the role of ENSO and IOD in hydro-climate dynamics using SWAT and multi-dimension wavelet analysis

  • 期刊论文

  • 发表日期：

    2026年1月3日

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  • Hanumapura Kumaraswamy Yashas Kumar,
  • Kondeti Poojitha,
  • Kumble Varija

摘要

Under future changing climate conditions, hydro-climate variability is poised to intensify with extreme events surpassing historical thresholds. While the influence of El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on global and regional hydro-climates are well-documented, their specific effects at finer spatial scales remain less explored. This study significantly advances our understanding by establishing a teleconnection between these multifaceted climate oscillations and the Aghanashini River Basin (ARB), a Ramsar wetland site and a part of UNESCO biodiversity hotspot, identifying the vulnerability of this fragile ecosystem to the intensifying impacts of changing climate. Non-parametric biwavelet and multiwavelet analyses revealed significant shared power (95% significance level) between combined ENSO-IOD phases and hydro-climate variables (rainfall, temperature and streamflow) at periodicities exceeding 12 months, with an Average Wavelet Coherence Power exceeding 0.70, indicating a stronger combined influence compared to individual oscillations. Positive ENSO-IOD phases increased mean rainfall by 12.76%, leading to extreme wet conditions with water yield ranging from 2.75 × 109 to 0.2 × 109 m3 during monsoon months, while negative phases induced droughts. Using the enhanced Soil and Water Assessment Tool (SWAT), the projected increase in the frequency and intensity of consecutive ENSO-IOD events (0–4/31 years) are expected to exacerbate hydrological extremes, causing more frequent and severe floods and droughts and significantly altering salinity levels (> 30 ppt) in the ARB river ecosystem. These changes threaten biodiversity and river health, calling for urgent global action through adaptive water management and community-led restoration to ensure long-term sustainability.