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Abstract <p>Understanding the evolution of extreme rainfall patterns due to climate change is essential for climate-resilient agricultural planning and hydrological risk management. This study examined long-term (1965–2022) daily rainfall data from 44 stations in the coastal, Western Ghats, and arid agroclimatic regions of southern Karnataka, utilizing fifteen extreme precipitation indices according to the India Meteorological Department (IMD) and Expert Team on Climate Change Detection and Indices (ETCCDI) standards. Trend detection was conducted utilizing the Mann–Kendall (MK) test and the Innovative Trend Analysis (ITA) method, facilitating the evaluation of both monotonic changes and transitions among low-, medium-, and high-intensity rainfall categories. The results indicated significant regional variability in extreme rainfall patterns. The coastal zone demonstrated considerable reductions in southwest monsoon heavy rainfall (HRE: -0.045&#xa0;days/year), very heavy rainfall (VHRE: -0.031&#xa0;days/year) and maximum 1-day and 5-day rainfall (RX1: -0.39&#xa0;mm/year, RX5: -1.94&#xa0;mm/year), alongside an increase in light (LRE: 0.136&#xa0;days/year) and moderate rainfall (MRE: 0.092&#xa0;days/year) occurrences and reduced wet spell durations (WN: 0.046&#xa0;days/year). This indicates a fragmentation of monsoonal precipitation, probably affected by diminishing westerlies and modified moisture transport from the Arabian Sea. Conversely, the arid region witnessed substantial rises in heavy precipitation occurrences (HRE: 0.005&#xa0;days/year), RX1 (0.181&#xa0;mm/year), RX5 (0.269&#xa0;mm/year), and the duration of wet spells, aligning with intensified convective activity attributable to land surface warming and augmented atmospheric moisture availability. The Western Ghats exhibited predominantly stable extreme rainfall indices, with only increases observed in rainy days (RD: 0.187&#xa0;days/year) and light rainfall events (LRE: 0.161&#xa0;days/year), indicating that orographic processes continue to mitigate intense climatic variations in the region. The integrated MK–ITA framework identified indices demonstrating monotonic trends versus those displaying non-monotonic or category-specific behavior, providing more refined insights than traditional trend tests alone. The results underscore evolving climatic changes with direct consequences for water management, agriculture, infrastructure development, and disaster risk mitigation throughout southern Karnataka.</p> Graphical abstract <p></p>

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Trends and variability of extreme rainfall events in varied agroclimatic regions of Southern Karnataka

  • 期刊论文

  • 发表日期：

    2026年5月31日

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  • Shankarappa Sridhara,
  • Mahesh Haroli,
  • Hemareddy Thimmareddy,
  • Santanu Kumar Bal,
  • Bappa Das

摘要

Abstract

Understanding the evolution of extreme rainfall patterns due to climate change is essential for climate-resilient agricultural planning and hydrological risk management. This study examined long-term (1965–2022) daily rainfall data from 44 stations in the coastal, Western Ghats, and arid agroclimatic regions of southern Karnataka, utilizing fifteen extreme precipitation indices according to the India Meteorological Department (IMD) and Expert Team on Climate Change Detection and Indices (ETCCDI) standards. Trend detection was conducted utilizing the Mann–Kendall (MK) test and the Innovative Trend Analysis (ITA) method, facilitating the evaluation of both monotonic changes and transitions among low-, medium-, and high-intensity rainfall categories. The results indicated significant regional variability in extreme rainfall patterns. The coastal zone demonstrated considerable reductions in southwest monsoon heavy rainfall (HRE: -0.045 days/year), very heavy rainfall (VHRE: -0.031 days/year) and maximum 1-day and 5-day rainfall (RX1: -0.39 mm/year, RX5: -1.94 mm/year), alongside an increase in light (LRE: 0.136 days/year) and moderate rainfall (MRE: 0.092 days/year) occurrences and reduced wet spell durations (WN: 0.046 days/year). This indicates a fragmentation of monsoonal precipitation, probably affected by diminishing westerlies and modified moisture transport from the Arabian Sea. Conversely, the arid region witnessed substantial rises in heavy precipitation occurrences (HRE: 0.005 days/year), RX1 (0.181 mm/year), RX5 (0.269 mm/year), and the duration of wet spells, aligning with intensified convective activity attributable to land surface warming and augmented atmospheric moisture availability. The Western Ghats exhibited predominantly stable extreme rainfall indices, with only increases observed in rainy days (RD: 0.187 days/year) and light rainfall events (LRE: 0.161 days/year), indicating that orographic processes continue to mitigate intense climatic variations in the region. The integrated MK–ITA framework identified indices demonstrating monotonic trends versus those displaying non-monotonic or category-specific behavior, providing more refined insights than traditional trend tests alone. The results underscore evolving climatic changes with direct consequences for water management, agriculture, infrastructure development, and disaster risk mitigation throughout southern Karnataka.

Graphical abstract