عنوان مقاله [English]
Management and optimal use of water in agriculture is essential for management and conservation of water resources. This study aimed to evaluate the effect of seasonal precipitation fluctuations on annual rainfed yield. Monthly precipitation data for 26 rainfall stations with Statistical period of 1992 to 2014 of the east part of Lake Urmia basin were used. Clustering was done with Ward and K-means methods. The homogeneity of cluster was checked through H-Statistics method and homogeneous clusters were shown in GIS environment. The effect of seasonal precipitation was compared with annual rainfed yield. Results showed that the effect of precipitation in the spring, autumn and winter on the amount of rainfed yield is positive and precipitation in these seasons has a remarkable effect on increasing yield. In the three seasons, precipitation caused an increase of soil moisture storage which is used in summer. But, there is an inverse relationship between precipitation and annual rainfed yield in the summer. In order to identify areas combined with increased precipitation and rainfed yield, iso-line of precipitation seasons with the rainfed yield of the study area was drawn. The results of this line showed that in the spring, autumn and winter at the Daryan, Lighvan, Khormazard, Sahlan, Harvy, Saidabad, ShirinKandy, Ghorigol, Tabriz and Moghanjigh, the increased amount of pricipitation is directly related to the amount of yield. These areas can introduce more eligible rainfed cultivation in East of Lake Urmia and recognition of the effects of precipitation on yield rainfed areas can be more practical and reliable.