A Comprehensive Analysis of Rainfall Trends and Climatic Breakpoints in Eastern Kermanshah Province: A Statistical Perspective on Climate Change

Abstract

Climate change, an escalating global phenomenon, presents significant challenges with diverse impacts, particularly in developing regions. This study conducts a detailed statistical analysis of long-term rainfall trends and climatic disruptions at six meteorological stations in Kermanshah Province, Iran, spanning 1951 to 2023. The analysis identifies significant trends and breakpoints in rainfall patterns using the Mann-Kendall test, Sen's slope estimator, and Pettitt’s test. Results reveal a consistent decline in annual rainfall at five stations—Kermanshah, Ravansar, Songhor, Sahneh, and Bisotun—while Harsin exhibits a slight increase. Bisotun records the sharpest decline, with a 26.86% reduction in annual rainfall, equivalent to −5.38 mm per year, followed by Songhor with a 28.45% decline, reflecting heightened vulnerability in these areas.Conversely, Harsin demonstrates a 20.53% increase in annual rainfall after 1967, showcasing variable climatic responses within the region. Pettitt’s test identifies the 1990s as the predominant period for abrupt rainfall shifts, coinciding with global phenomena such as El Niño and La Niña. These shifts significantly reduced mean annual rainfall in critical locations, including Bisotun, where the mean declined from 540.9 mm to 395.61 mm after 1995. The findings emphasize the profound impact of climate change on regional hydrological dynamics, threatening water resources, agriculture, and livelihoods. The study underscores the urgency of adaptive water management strategies to address rainfall variability and recommends further research on the interaction between global atmospheric phenomena and local climatic shifts to inform effective mitigation and adaptation policies.

Keywords

• mann-kendall test
• sen’s slope estimator
• pettitt’s test
• time series analysis
• rainfall variability