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<p>Drought remains a critical hydroclimatic hazard in Nigeria, affecting agriculture, water resources, and livelihoods across its different ecological zones. This study aims to assess drought characteristics and their climatic interactions across Nigeria using the Palmer Drought Severity Index (PDSI) based on three potential evapotranspiration (PET) models: Penman-Monteith (PM), Hargreaves (HG), and Thornthwaite (TW). Monthly climatic variables spanning 1979–2021 at a 0.5<sup>o</sup> by 0.625<sup>o</sup> latitude and longitude resolution were obtained from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data and aggregated to annual and decadal scales. Using the PDSI technique, drought duration, intensity, frequency, severity, trends, change points, and climate sensitivity were analyzed. The Sahel region showed the highest drought frequency under PDSI-TW (77%) and maximum intensity of -1.40 at the 2013 change point and peak cross-correlation with precipitation (<i>R</i> = 0.62). The Guinea Savannah experienced peak drought intensity of -1.55 (PDSI-TW), maximum frequency of 75% (PDSI-PM), and a significant decreasing trend (slope = -0.018, <i>p</i> &lt; 0.01), with strong climatic sensitivity (<i>R</i> = 0.78 with precipitation). In the Rainforest, maximum drought intensity reached − 1.69 (PDSI-HG), frequency peaked at 92% (PDSI-HG), and decreasing trends were most pronounced under PDSI-TW (slope = -0.026, <i>p</i> &lt; 0.001), with significant precipitation sensitivity (<i>R</i> = 0.62). The Coastal region experienced the most extreme intensity values (PDSI-HG: -3.78) and drought frequencies (up to 67%) at the 2016 change point and high precipitation correlation (<i>R</i> = 0.76). The results suggest that PDSI-TW is more sensitive to temperature-driven drought signals in arid zones, while PDSI-HG and PDSI-PM show stronger responsiveness in humid and coastal environments, although their performance varies depending on local climatic conditions. These results provide useful insights for improving localized drought assessment and may support the development of region-specific adaptation strategies when combined with additional data sources.</p>

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Assessment of drought characteristics and climatic interactions in a tropical region using the palmer drought severity index with multiple evapotranspiration models

  • 期刊论文

  • 发表日期：

    2026年4月16日

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  • Olusola Samuel Ojo,
  • Inalegwu Adoche Ngbede,
  • Oluwafunmilayo Rita Ajakaiye

摘要

Drought remains a critical hydroclimatic hazard in Nigeria, affecting agriculture, water resources, and livelihoods across its different ecological zones. This study aims to assess drought characteristics and their climatic interactions across Nigeria using the Palmer Drought Severity Index (PDSI) based on three potential evapotranspiration (PET) models: Penman-Monteith (PM), Hargreaves (HG), and Thornthwaite (TW). Monthly climatic variables spanning 1979–2021 at a 0.5o by 0.625o latitude and longitude resolution were obtained from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data and aggregated to annual and decadal scales. Using the PDSI technique, drought duration, intensity, frequency, severity, trends, change points, and climate sensitivity were analyzed. The Sahel region showed the highest drought frequency under PDSI-TW (77%) and maximum intensity of -1.40 at the 2013 change point and peak cross-correlation with precipitation (R = 0.62). The Guinea Savannah experienced peak drought intensity of -1.55 (PDSI-TW), maximum frequency of 75% (PDSI-PM), and a significant decreasing trend (slope = -0.018, p < 0.01), with strong climatic sensitivity (R = 0.78 with precipitation). In the Rainforest, maximum drought intensity reached − 1.69 (PDSI-HG), frequency peaked at 92% (PDSI-HG), and decreasing trends were most pronounced under PDSI-TW (slope = -0.026, p < 0.001), with significant precipitation sensitivity (R = 0.62). The Coastal region experienced the most extreme intensity values (PDSI-HG: -3.78) and drought frequencies (up to 67%) at the 2016 change point and high precipitation correlation (R = 0.76). The results suggest that PDSI-TW is more sensitive to temperature-driven drought signals in arid zones, while PDSI-HG and PDSI-PM show stronger responsiveness in humid and coastal environments, although their performance varies depending on local climatic conditions. These results provide useful insights for improving localized drought assessment and may support the development of region-specific adaptation strategies when combined with additional data sources.