In general, the possible variability resulting from climate change in precipitation, soil moisture and surface runoff on natural systems and human populations will have a major impact. Thus, in this study using two non-parametric Man-Kendall and Sen’s estimator methods, basin discharge and precipitation trend Kashkan were examined agricultural water during 1968 - 2010. Analysis of the distribution of the data indicates that the occurrence time of peak flow in all rivers in the basin, the maximum precipitation event is part of the corresponding Madyanrvd. So that the peak rainfall in winter and are the peak discharge in spring. in this direction regard showed that the melting snow in the spring, an important factor in increasing the flow rate and cause inconsistent this season than any other season of the year is the time between precipitation and discharge. The results of the statistical tests revealed that both precipitation trend in the annual series of incremental stations and stations in the northern basin of the southern basin is decreasing. The scale seasonal precipitation trends in spring and in autumn and winter is decreasing, while the rate of annual and seasonal scale is decreasing. The findings showed that the displacement of the phase change in precipitation has occurred. In general, rainfall intensity change rate and review Kashkan geographic area indicates that this value can be attributed to precipitation changes the entire flow, but human intervention in the environment, changes in flow caused by intense precipitation in some branches of the critical phase.