Aiming at the problem of lacking real-time monitoring of suspended sediment content in mountainous rivers, the turbidity and suspended sediment content of the rivers were monitored, and the influences of light intensity, velocity, particle size and water sediment content on turbidity were analyzed. A relationship model between turbidity and suspended sediment content was established. The results show that: 1) Light intensity has the greatest influence on turbidity. According to the relationship between the light intensity and turbidity, light intensity (E) is divided into three intervals, E ≤ 6 800 lx, 6 800 lx < E≤ 22 000 lx and E > 22 000 lx. In corresponding to the three intervals, the relationship model between turbidity and suspended sediment content is determined. 2) The flow velocity mainly affects the distribution of sediment particles in the upper layer. The turbidity of the measured area at the flow velocity of 0.16 m/s is greater than that at the flow velocity of 0.018 m/s; 3) When the particle size of the sediment particles is larger than the critical particle size driven by the lifting velocity, it will be deposited at the bottom of the channel. Therefore, the larger the proportion of particles larger than the critical particle size in the sediment gradation, the smaller the suspended sediment content and the smaller the turbidity; 4) The larger the sediment content of the water body, the more suspended sediment carried in the process of water and sediment transport, and the greater the turbidity of the upper water sample in the measured area; 5) Using the three relationship models of turbidity and suspended sediment content determined in this study, the average relative errors of predicted suspended sediment content and actual suspended sediment content are 7.22%, 10.00% and 8.58%, respectively. According to the turbidity measured in different light intensity intervals under natural conditions, the suspended sediment content in the measured area can be obtained. To sum up, since the turbidity can be measured continuously and quickly on site, it is feasible to apply this model to real-time monitoring of suspended sediment concentration in mountainous rivers.
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