Trend of Precipitation Over the Past three Decades, North of Lake Uremia, Using the Method of Man-Kendall

The goal of this survey is to study the possible deviance of climatic elements of precipitation from its normal condition in North and East of Lake Uremia. Therefore at first, mean time series of precipitation of selected synoptic meteorology stations of the area in (1976-2005) were collected and adjusted. Statistical defects of some series were resolved by doubled mass method. In order to examination and recognition of series temporal changes, the T statistic of Kendal test and statistical-graphical method of Man-Kendall were used and time and type of data changes was determined. Research results show that being accidental of data is strongly rejected and trend situation is dominant over data. According to examination of graphical diagrams, changes in U and Uʹ components of precipitation of the area in the past three decades have undergone some changes. Regarding spatial and temporal distributions, most of the wet period precipitations in area particularly in North and East of Uremia Lake have sudden and meaningful changes. The seasonal variations, winter rainfall region East during the 1990s and 2000s, severe sudden changes, especially during the 2002 and 2005 mutations have a significantly negative trend is the rule.