تحلیل روند تغییرات بارش و تعیین وضعیت خشکسالی و ترسالی حوضه آبریز کن در سالهای اخیر

Rainfall is of the most important elements in climatic studies and climate change is mainly due to changing precipitation amount. Therefore, rainfall is discussed in most climatic researches, especially those which are related to determining dry/wet periods. Anomalies of climate elements are of the main factors causing extreme events such as floods, droughts, desertification etc. in most parts of the world including Iran. Precipitation anomaly percent (PAP( is an important measure in drought assessment. Current study applies linear regression and Mann-Kendal tests on data from Chitgar synoptic weather station in order to determine the trend and change points in precipitation time series in Kan watershed during 1994-2014. Also moving average and anomalies for total annual precipitation and mean annual temperature were calculated and dry/wet years were recognized based on them. The results show that precipitation trend has been negative in Kan watershed, in general, during two recent decades, though it is not meaningful (in 5% significance). In addition, the investigations showed that the studied area has faced slight and average drought in 1990s, however after that, dry/wet years changed from year to year. Totally there was no severe and extreme drought in Kan watershed during two past decades, but it can be said that most years were considered as dry years during this period.