investigation of trend of precipitation variation using non-parametric methods in charmahal o bakhtiari province

climatic parameters in time and space scales of change are for many reasons of changes and how they should be based on observations using a statistical method to be determined. analysis of the most widely used statistical methods that assess potential climate change on hydrological time series, such series of precipitation, temperature and flow rate used. this study of 11 synoptic,rain gage and climatology stations with 30 years during the years 1979 to 2009 period is charmahal o bakhtiari province.mann-kendall non-parametric and  sen estimate tests were used for the purpose of the study.the results showed that 11 stations were the only station in sepid dasht 95 and 99 percent had significant levels decline and changes in the slope is negative and other gage stations does not have significant trends. the results of this study can be in the long-term planning for water resources management, irrigation scheduling and prediction of future droughts in the province can be used