Document Type : Original Article
Department of civil engineering, Faculty of engineering, Yasouj University, Yasouj , Iran
Department of civil engineering, Faculty of engineering, Yasouj University, Yasouj, Iran
Department of mathematics, Faculty os Science, Yasouj University, Yasouj, Iran
Climate change and global warming are occurring as the most important environmental problem. It is necessary to study the trend of meteorological variables in order to detect climate change in each region. In this study, the trends of variables related to temperature (minimum, absolute minimum, maximum, absolute maximum and average) and precipitation (total precipitation, frequency of days with precipitation and maximum daily precipitation) in the annual time scale were investigated. Trend analysis was performed using non-parametric Mann-Kendall and Sen's slope estimator in 15 synoptic stations of Hormozgan, Bushehr and Sistan and Baluchestan provinces, which had complete data in the period of 1987-2019. Then, zoning maps of climate variables trends were prepared in Arc GIS software. The results showed that 3 temperature variables including: minimum, maximum and average had a significant upward trend in most of the area. The frequency of occurrence of significant upward trend related to temperature variables for each station showed that the stations of Bandar Abbas, Kish Island, Zahedan, Zabol and Iranshahr had a significant upward trend in 4 of the 5 temperature trends studied. Total rainfall in the region showed no significant trend, maximum 24-hour rainfall had a significant increasing trend only in Bushehr-Coastal Station and the frequency of days with rainfall in Bushehr-coastal had a significant decreasing trend. The results of the Sen's slope estimator showed that during 33 years, the highest rate of change of temperature variables, related to the absolute minimum, was 3.59 ° C in Kish Island. The maximum rainfall in Bushehr-coastal increased by 16.5 mm and the frequency of days with rainfall decreased by 11 days.