ObjectiveRunoff sediment concentration is an important variable in monitoring hydrological processes and quantifying soil erosion. Methodological improvements in measuring sediment concentration are critical to the automatic, efficient and accurate estimation of soil losses, and could also guide soil and water conservation practices.
MethodWe collected and analyzed soil samples from different provinces in China, and developed a weighing-based empirical model for estimating sediment concentration. We also investigated factors（specific gravity of sediment, volume of sample, water temperature）which may influence the accuracy of the method.
ResultThe results showed that measured data agreed well with true values, and the method for estimating sediment concentration was accurate enough for practical use. When the sediment concentration was between 5 g/L and 20 g/L, the average relative error is less than 20%; when the sediment concentration was between 20 g/L and 200 g/L, the average relative error is less than 5%. Both specific gravity of sediment and temperature (P > 0.05) had no significant effect on the accuracy of the method, it is therefore reasonable to use the average specific gravity of the top-layer soil in the calculations, and the range of variation was between 2.50 and 2.70. However, the accuracy was significantly influenced by the measurement of the sample’s volume, how to accurately measure the volume of sample is the key to invent automatic monitoring machine for estimating sediment concentration in surface runoff.
ConclusionThe weighing method has simple operation and high accuracy. It has a good application prospect in the study of inventing automatic monitoring machine for estimating sediment concentration in surface runoff.