Hydrological and Sedimentary Responses of an Alpine River to a Heavy Weather Event: A Comprehensive Investigation in the Cordevole River

In fluvial systems, sediment transport is characterized by complex rela-tionships with rainfalls and flow conditions. These relationships are not fully understood, particularly, in mountain basins. This is compounded by the effects of climate change on sensitive environments, such as alpine river systems, where novel runoff-and sediment-dynamics are being triggered. An opportunity to address this knowledge gap lies in the acquisition of monitoring data and analyz-ing observed patterns. This work investigates the hydrological and sedimentary responses of an alpine river to a heavy weather event. Specifically, rainfall (R), water discharge (Q), turbidity (Tu), and bedload mobility (BL) were analyzed in the Cordevole River during the event that occurred between October 30 and Novem-ber 1, 2023. Q, Tu, and BL were monitored at Saviner (Rocca Pietore, BL), where the Cordevole River drains 109 km2. This monitoring system used an ultrasonic water level sensor (ARPA Veneto), a multiparameter water quality sonde, and 100 bedload tracers. The R recorded by the Arabba meteorological station (ARPA Veneto) exhibited a total amount of 71.2 mm in 72 h, a value corresponding to 6.2% of the mean annual precipitation. Notably, the highest rainfall intensity was 10.6 mm h−1 measured at 0:00 on October 31. Such conditions led to QP equal to 44.2 m3 s−1 on October 31. This peak occurred 2 h after the peak rainfall and represents the third-largest flood event recorded over the last decade. Tu showed multiple peaks (~ 3000 NTU), stressing a complex suspended sediment dynamic. Also, the flow conditions induced an average travel distance of 70.4 m in the bed-load tracers, entraining them up to the grain size class of 256 mm. The findings stressed the need for a deeper understanding of these processes, especially in light of ongoing climate change impacts.