Figure 3 Observations of discharge and suspended sediment concentration (SSC) during three hydrological years. Observations of the discharge are represented by blue triangles and observations of SSC are represented by orange dots.
The R2 value for the SSC-Q rating curve for the entire study period was relatively low at 0.40 (p < 0.05; Figure 4a). The SSC-Q relation exhibited a large scatter for SSC for discharge values above 25 m3/s. Due to the poor fit, the rating curve was fitted by hydrological years to analyze the differences between each hydrological year (Figure 4b-d). The empirical relationship between SSC and discharge improved when the data was divided by hydrological years (Figure 4b-d). In particular, the largest R2 value can be found in the hydrological year of 2015 (R2=0.62). Scatter plots for 2015 and 2016 showed distinct power-law increases in SSC for discharge above 20m3/s.
For discharge above 25m3/s (Figure 4b-d), which were recorded during ablation seasons, large scatters were observed for all 3 hydrological years The data was further analyzed by considering its inter-annual seasonal variations (Figure S3 and Table 1). Subsequently, the SSC-Q relationship improved when the data was categorized into falling and rising stages throughout the study period. However, during the falling stage from August 2013 to January 2014, there was still no significant correlation between discharge and SSC (R2= 0.11). The coefficient of correlation was higher during the rising stage than the falling stage for all hydrological years.