In the view of geomorphology, the study on sediment yield is not only an important issue that needs to be addressed, but they are vital for the prediction and evaluation of natural hazards. Many studies are focused on the accuracy of model performance, although sediment yield researches based on various types of geologies are also important. To investigate the properties of sediment yields on two different geologies, i.e. granite and gneiss in small watersheds, the GeoWEPP model, which is integrated with GIS and Water Erosion Prediction Project model, was applied in this research. During the monitoring period, the amount of sediment yield was measured to be 270.54 tons at the granite area and 31 tons at the gneiss area. The results showed that when the measured data and simulated data were compared, an acceptable difference of –12.46 and +0.96 were observed for the granite area and gneiss area, respectively. However, though the model showed acceptable performance, it is still necessary to compare the model assumptions with the surveyed geomorphological investigations. This suggestion is necessary due to some geomorphological variations detected in both research sites, which deviates from the model assumption.