Suspended sediment transport monitoring: relationship between hydrological parameters and discharges

At the outlet of three different mountain basins (Sillaro, Lavino, Savena) we set up a flow meter in order to measure river stage and to command a water sampler. Hydraulic level is measured every 30 minutes and suspended sediment concentration (S.S.C) and turbidity are measured on the water samples collected. Precipitation height is calculated using data from rain gauges scattered across the basins: rainfall height is recorded every 30 minutes. The Sillaro Torrent has been monitored since April 1997, the Lavino Torrent since September 1998 and the Savena Torrent since October 2000. The parameters used in the analysis, calculated on a storm event basis, are as follows: rainfall height (P), maximum rainfall intensity (Imax), mean rainfall intensity (Iave), the product PImax, the USLE rainfall erosion index (E.I.), average and maximum water flow (Qave and Qmax), the runoff coefficient, rainfall and discharge duration, and maximum and average suspended sediment yield. Initially, a multiregression analysis has been performed to compare the “sediment-based” variables with the other variables. For all the three basins, S.S.C and “sediment-based” variables better correlate to rainfall erosion index E.I. and other “rainfall-based” variables, whereas discharge is scarcely correlated to average S.S.C..