Annual hysteresis pattern, dynamics and memory effects of suspended sediment fluxes in an alpine basin, in the last decade (2006-2015).

The dynamics of surface outflow and suspended sediment transport have not yet been fully understood, and in this context, long-term monitoring is rare, particularly in mountain basins. The dynamics of suspended load and the water flow rates result from complex interactions. In this perspective, the hysteresis cycle analysis can be an indica-tor of the different dynamics of runoff and sediment transport. The aim of this study is to analyze the existing annual hysteresis relationships between the water runoff and the suspended sediment transport in an alpine basin. The Rio Cordon is a bed-rock tor-rent, with step-pool bedforms, draining an area of approximately 5 km2, located in the Veneto Region (Italy). The monitoring station at the basin outlet, since 1986, has been able to continuously measure water discharge and sediment transport (suspended and bedload). In the present work, the last decade (2006-2015) has been analyzed, evaluat-ing the annual hysteresis cycles and defining the dynamics of suspended load. The in-vestigation of the hysteresis cycles shows predominantly a clockwise and triangular shape loop, indicating therefore that the snowmelt is the largest suspended sediment contributor annually: the maximum values of fine material recorded during the snowmelt were 503.6 t in 2009, while during summer and autumn it was 156.4 t (2015) and 84.2 t (2014) respectively. This work highlights the key role played by the snow-melt on the suspended sediment transport over the last decade. In this sense, previous studies carried out in the Rio Cordon basin showed greater heterogeneity in the annu-al cycles of hysteresis.