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

Document Type : Research Paper

Authors

1 Department of Arid and Mountainous Regions Reclamation, College of Agriculture and Natural Resources, University of Tehran, Karaj, Alborz, Iran

2 Assistant Prof, International Research Center for Living with DESERT

3 Agriculture Faculty, Ilam University, Ilam, Iran

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.

References
Abdul Talib, S. A., Idris, W. M. R., Neng, L. J., Lihan, T., & Abdul Rasid, M. Z. (2024). Irregularity and time series trend analysis of rainfall in Johor, Malaysia. Heliyon, 10(9), e30324. https://doi.org/https://doi.org/10.1016/j.heliyon.2024.e30324
Alley, R. B., Marotzke, J., Nordhaus, W. D., Overpeck, J. T., Peteet, D. M., Pielke, R. A., Pierrehumbert, R. T., Rhines, P. B., Stocker, T. F., Talley, L. D., & Wallace, J. M. (2003). Abrupt Climate Change. Science, 299(5615), 2005-2010. https://doi.org/doi:10.1126/science.1081056
Antwi-Agyei, P., Fraser, E., Dougill, A., Stringer, L., & Simelton, E. (2012). Mapping the vulnerability of crop production to drought in Ghana using rainfall, yield and socioeconomic data. Applied Geography, 32, 324–334. https://doi.org/10.1016/j.apgeog.2011.06.010
Arfasa, G. F., Owusu-Sekyere, E., & Doke, D. A. (2024). Climate Change Projections and Impacts on Future Temperature, Precipitation, and Stream flow in the Vea Catchment, Ghana. Environmental Challenges, 14, 100813. https://doi.org/https://doi.org/10.1016/j.envc.2023.100813
Atiah, W., Mengistu Tsidu, G., Amekudzi, L., & Yorke, C. (2020). Trends and interannual variability of extreme rainfall indices over Ghana, West Africa. Theoretical and Applied Climatology, 140. https://doi.org/10.1007/s00704-020-03114-6
Bayram, H., & Öztürk, A. B. (2021). Global climate change, desertification, and its consequences in Turkey and the Middle East. Climate change and global public health, 445-458
Beaulieu, C., Chen, J., & Sarmiento, J. L. (2012). Change-point analysis as a tool to detect abrupt climate variations. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 370(1962), 1228-1249. https://doi.org/doi:10.1098/rsta.2011.0383
Broström, G. (1994). Change-point tests in hydrology. Journal of Hydrology, 154(1-4), 373-381.
Cai, W., Wang, G., Santoso, A., McPhaden, M. J., Wu, L., Jin, F.-F., Timmermann, A., Collins, M., Vecchi, G., Lengaigne, M., England, M. H., Dommenget, D., Takahashi, K., & Guilyardi, E. (2015). Increased frequency of extreme La Niña events under greenhouse warming. Nature Climate Change, 5(2), 132-137. https://doi.org/10.1038/nclimate2492
 
Chakraborty, P., & Mandai, A. (2008). Rainfall characteristics of Sagar Island in Sundarban, West Bengal. Indian Journal of Soil Conservation, 36(3), 125-128.
Dailidiene, I., Baudler, H., Chubarenko, B., & Navrotskaya, S. (2011). Long term water level and surface temperature changes in the lagoons of the southern and eastern Baltic. Oceanologia, 53. https://doi.org/10.5697/oc.53-1-TI.293
Erlat, E., & Türkeş, M. (2013). Observed changes and trends in numbers of summer and tropical days, and the 2010 hot summer in Turkey. International Journal of Climatology, 33(8), 1898-1908.
Gocic, M., & Trajkovic, S. (2013). Analysis of changes in meteorological variables using Mann-Kendall and Sen's slope estimator statistical tests in Serbia. Global and Planetary Change, 100, 172-182.
Haktanir, K., Namlı, A., & Omar, S. (2004). The Prospects of the Impact of Desertification on Turkey, Lebanon, Syria and Iraq. In (pp. 139-154). https://doi.org/10.1007/978-94-007-0973-7_9
Helsel, D. R., Hirsch, R. M., Ryberg, K. R., Archfield, S. A., & Gilroy, E. J. (2020). Statistical methods in water resources [Report](4-A3). (Techniques and Methods, Issue. U. S. G. Survey. https://pubs.usgs.gov/publication/tm4A3
 
Ipcc, Masson-Delmotte, V., Zhai, P., Pörtner, H.-O., Roberts, D., Skea, J., Shukla, P., Pirani, A., Moufouma-Okia, W., Péan, C., Pidcock, R., Connors, S., Matthews, R., Chen, Y., Zhou, X., Gomis, M., Lonnoy, E., Maycock, T., Tignor, M., & Tabatabaei, M. (2018). Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. https://doi.org/10.1017/9781009157940
Jakhar, P., H C, H., Naik, B., & Barman, D. (2011). Probability analysis of rainfall characteristics of Semiliguda in Koraput, Orissa. Indian Journal of Soil Conservation, 39, 9-13.
Karaburun, A., Demirci, A., & Kara, F. (2011). Analysis of spatially distributed annual, seasonal and monthly temperatures in Istanbul from 1975 to 2006. World Applied Sciences Journal, 12, 1662-1675
Kakkar, A., Rai, P., Mishra, V., & Singh, P. (2022). Decadal trend analysis of rainfall patterns of past 115 years & its impact on Sikkim, India. Remote Sensing Applications: Society and Environment, 26, 100738. https://doi.org/10.1016/j.rsase.2022.100738
Kumar, V., & Jain, S. K. (2010). Trends in seasonal and annual rainfall and rainy days in Kashmir Valley in the last century. Quaternary International, 212(1), 64-69. https://doi.org/https://doi.org/10.1016/j.quaint.2009.08.006
Kundzewicz, Z., & Robson, A. (2000). Detecting trend and other changes in hydrological data. World Meteorological Organization.
Kundzewicz, Z., & Robson, A. (2004). Change detection in hydrological records—a review of the methodology / Revue méthodologique de la détection de changements dans les chroniques hydrologiques. Hydrological Sciences Journal-journal Des Sciences Hydrologiques - HYDROLOG SCI J, 49, 7-19. https://doi.org/10.1623/hysj.49.1.7.53993
Kwawuvi, D., Mama, D., Agodzo, S., Bessah, E., Yangouliba, G., & Aklamati, W. (2023). Potential consequences for rising temperature trends in the Oti River Basin, West Africa. Frontiers in Climate, 5. https://doi.org/10.3389/fclim.2023.1184050
Liu, L., Xu, Z.-X., & Huang, J.-X. (2012). Spatio-temporal variation and abrupt changes for major climate variables in the Taihu Basin, China. Stochastic Environmental Research and Risk Assessment, 26, 777-791.
Longobardi, A., & Villani, P. (2010). Trend analysis of annual and seasonal rainfall time series in the Mediterranean area. International Journal of Climatology, 30(10), 1538-1546. https://doi.org/https://doi.org/10.1002/joc.2001
Modarres, R., & Sarhadi, A. (2009). Rainfall trends analysis of Iran in the last half of the twentieth century. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 114. https://doi.org/10.1029/2008JD010707
Nath, S., Mathew, A., Khandelwal, S., & Shekar, P. R. (2023). Rainfall and temperature dynamics in four Indian states: A comprehensive spatial and temporal trend analysis. HydroResearch, 6, 247-254. https://doi.org/https://doi.org/10.1016/j.hydres.2023.09.001
New, M., Todd, M., Hulme, M., & Jones, P. (2001). Precipitation measurements and trends in the twentieth century. International Journal of Climatology, 21(15), 1889-1922. https://doi.org/https://doi.org/10.1002/joc.680
Panda, A., & Sahu, N. (2019). Trend analysis of seasonal rainfall and temperature pattern in Kalahandi, Bolangir and Koraput districts of Odisha, India. Atmospheric Science Letters, 20(10), e932. https://doi.org/https://doi.org/10.1002/asl.932
Pettitt, A. N. (1979). A Non-Parametric Approach to the Change-Point Problem. Journal of the Royal Statistical Society. Series C (Applied Statistics), 28(2), 126-135. https://doi.org/10.2307/2346729
Rangarajan, S., Thattai, D., Yellasiri, S. R. R., Vytla, R., Tedla, N., & Mandalemula, B. (2018). Detecting Changes in Annual and Seasonal Rainfall Patterns for Chennai, India. Journal of Hydrologic Engineering, 23(4), 05018001. https://doi.org/doi:10.1061/(ASCE)HE.1943-5584.0001630
Reduction, U. O. f. D. R. (2009). Adaptation to Climate Change by Reducing Disaster Risks: Country Practices and Lessons: Briefng 02. UN, Geneva.
Sen, P. K. (1968). Estimates of the regression coefficient based on Kendall's tau. Journal of the American statistical association, 63(324), 1379-1389.
Serrano, A., Mateos, V. L., & Garcia, J. A. (1999). Trend analysis of monthly precipitation over the iberian peninsula for the period 1921–1995. Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 24(1), 85-90. https://doi.org/https://doi.org/10.1016/S1464-1909(98)00016-1
Shri Kant, S. K., Meshram, S., & Sahu, K. C. (2014). Analysis of rainfall data for drought investigation at Agra U.P. Recent Research in Science and Technology, 6(1). https://updatepublishing.com/journal/index.php/rrst/article/view/1166
Tabari, H., Somee, B. S., & Zadeh, M. R. (2011). Testing for long-term trends in climatic variables in Iran. Atmospheric Research, 100(1), 132-140. https://doi.org/https://doi.org/10.1016/j.atmosres.2011.01.005
Undp, & Ha, W. (2007). Human Development Report 2007/2008: Fighting Climate Change: Human Solidarity in A Divided World. http://lst-iiep.iiep-unesco.org/cgi-bin/wwwi32.exe/[in=epidoc1.in]/?t2000=024938/(100). https://doi.org/10.1057/9780230598508
Wilks, D. S. (2019). Statistical Methods in the Atmospheric Sciences. Elsevier. https://books.google.com/books?id=VJqcDwAAQBAJ
WMO (1988) Analysing Long Time Series of Hydrological Data with Respect to Climate Variability. World Meteorological Organization, Geneva. .
Yue, S., Pilon, P., Phinney, B., & Cavadias, G. (2002). The influence of autocorrelation on the ability to detect trend in hydrological series. Hydrological Processes, 16(9), 1807-1829. https://doi.org/https://doi.org/10.1002/hyp.1095
Zhang, M., Liu, N., Harper, R., Li, Q., Liu, K., Wei, X., Ning, D., Hou, Y., & Liu, S. (2017).     A global review on hydrological responses to forest change across multiple spatial scales: Importance of scale, climate, forest type and hydrological regime. Journal of Hydrology, 546, 44-59. https://doi.org/https://doi.org/10.1016/j.jhydrol.2016.12.040.