Detecting the drivers of suspended sediment transport in an intermittent river: An event-based analysis

This study aimed to evaluate the drivers of suspended sediment (SS) transport by analyzing the flood events recorded from July 2010 to June 2011 in the Celone River basin (Apulia, S-E Italy). High-resolution data of rainfall, streamflow (Q), and measurements of suspended sediment concentrations (SSC) were used to carry out the multivariate analysis. Among the initial 18 variables, the Principal Component Analysis revealed that total volume (m), peak discharge (Qmax, m/s), and the flood duration were the most important factors influencing SS transport. Total rainfall and total kinetic energy recorded in the gauging station located in the lowland were also important factors, whereas the same rainfall variables recorded in the remote mountainous area of the basin had a minor influence on SS transport. Antecedent moisture conditions were significantly correlated only with the initial discharge of the flood. Hysteresis loops between SSC and Q were analyzed for each flood event by using the hysteresis index (HI). Results showed that this catchment was dominated by anticlockwise loops (negative values of HI) representative of delayed SS transport and of distant SS source areas in terms of the gauging station. These results also suggested that soil erosion from hillslopes was the dominant process compared with channel and bank erosion and that there was no exhaustion of sediment availability in the basin.