This investigation was aimed at developing an equation for suspended sediment yield prediction in Uromia Lake basin using regional analysis. Twenty-seven subbasins were selected based on data availability, data quality of sediment concentration and flow, and spatial distribution. From among the 27 subbasins seventeen and ten were respectively used to develop the regression equation and to validate the model. Twenty-two characteristics (explanatory variables) were chosen and assessed for each subbasin. Independent combinations of explanatory variables, arranged according to their correlations, were drawn to develop regression equations. The most suitable equation was selected from among the generated equations with respect to determination coefficient, and standard error of the estimate. Variables of product of mean annual discharge and subbasin area, sum of areas facing north and west (in percent), and the areas covered with Quaternary sediments as wdll as lithologies susceptible to erosion (included in the equation) explain over 94 percent of variation in suspended sediment yield. The final equation bears a 25 percent mean absolute error and its efficiency coefficient is worked out to be 0.99.
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