Water productivity is a suitable indicator in water potential analysis at a location in a region. In this study, changes in water use productivity are studied in spatial and temporal scale simultaneously. To evaluate temporal changes in water productivity in Hamadan region (Iran), Standard Precipitation Index (SPI) was analyzed and evaluated for drought, wet and normal conditions. To estimate regional water productivity, GIS and Kassam methods were coupled to estimate the Potential yield of rain-fed wheat in a developed rasterized grid network with 30×30 -km resolution. Results of this study indicate that the amount of water productivity in drought condition in comparison with the other two conditions was higher and from geographical point of view the southern parts of the region have higher potential production with compare to other locations of the province. The analysis shows the variation in amount of active radiation received by the earth surface is causing these differences.