Journal of Watershed Management Research

     Nitrate is one of the most important pollutants of surface water and underground water resources which has adverse effects on the health of consumers. Due to lack of sufficient opportunity and budget, in practice, full and timely sampling of all wells in each area is not possible. So the amount of nitrate in certain parts according to the adjacent groundwater is of particular importance in studies. In this study, data from 55 observation wells at 902 Km2 of Ghaemshahr-Jouyar plain were used. The accuracy of deterministic methods and geomorphology were evaluated to determine the most suitable method for determining spatial variations of nitrate. Among all the methods of interpolation, simple co-krigination with auxiliary calcium was identified as the most appropriate method. RMSE value was obtained 7.45 mg/l, MAE equal 5.95 mg/l and The coefficient of determination 0.47 . J-Bessel variogram model has the most powerful spatial structure. Using the land use map of Mazandaran province in the Research area also showed that the highest nitrate values were observed in the urban area. The results showed that the highest nitrate pollution was in Behnamir and from the coastal areas of the Caspian Sea and in all areas it is within the permitted limits.