Abstract: For erosion and hillslope surface/subsurface hydrology studies, the measurement of flow rate from runoff plots is very important. In this study, a new method capable of taking automatic measurements of sediment laden runoff flow rates was advanced. Hydraulic analysis was theoretically reasoned to formulate a function for the calibration of the sensor for clear water flow. Functional relationship was advanced for readjustment of the runoff flow rates for sediment-laden water. The calibration experiments indicated that the hydraulic relationship between the flow rate of clear water and the pulling force outputs well correlated the data sets, and the readjustment function of flow rate produces high accurate measurements. This high accuracy and reliability system should be used widely.