Trend Analysis and Detection of Seasonal Changes in climatic variables Temperature and Precipitation in the Mountainous part of Gharaghom Basin

As Iran is located in the middle part of the northern hemisphere, as well as complexity of topographic conditions caused a various climate on a local scale. Changes in the climatic variables such as temperature and precipitation have affected the hydrological conditions of the basin directly and indirectly. Gharaghom Basin is located in the northeastern part of Iran on the border between Iran, Afghanistan, and Turkmenistan. Harriroud and Keshafroud as the main rivers in the basin originate from the Hindu Kush Mountains in Afghanistan and Binalood in Khorasan Province, respectively. This research studied the seasonal effect of climatic variables on hydrological characteristics in the upstream mountainous regions of Gharaghom Basin. The trend analysis of Mann _Kendall (MK) was used to detect the trend of temperature and precipitation during different seasons. Although the lowest monthly significance is related to the precipitation variable, the highest significance for all stations has corresponded to the minimum and maximum temperature variables respectively. The minimum temperature has much more affected than the maximum temperature due to climate change and global warming has caused an increase in the monthly minimum and maximum temperature in the most seasons in different parts of the Basin. We expect an increasing trend of minimum temperature following the reduction of snow and solid precipitation, melting snow, and ice resources in mountainous upstream parts of the basin. The main disorders were not statistically significant in the behavior of seasonal and monthly precipitation trends and all significant trends in precipitation almost showed decreasing trends corresponding to winter. The results of this paper are robust in agreement with the other research report in case of an increasing trend in minimum and maximum temperature respectively in the most regions of mid -latitudes and disorders in precipitation behavior in endanger water resources of upstream mountainous regions.