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This paper investigates nearly 30 years of monitoring of sediment fluxes in an instrumented Alpine basin (Rio\ud Cordon, Italy). The collected bedload and suspended sediment transport data allows sediment dynamics to be analyzed\ud at different time scales, ranging from short- (single event) to long-term (three decades). The Rio Cordon\ud monitoring station has been operating since 1986, continuously recording water discharge, bedload and\ud suspended load. At the flood event scale, a good relationshipwas found between peak discharges (Qpeak) andsediment\ud load (bedload and suspended load). The inter-annual sediment yields were analyzed, also assessing the\ud contribution of the single floods to the total sediment budget. The annual suspended load ranges from 10 to\ud 2524 t yr−1, while the bedload varies from 0 to 1543 t yr−1. The higher annual yields were recorded in the\ud years when large floods occurred, highlighting that the sediment budget in the Rio Cordon is strongly controlled\ud by the occurrence of high magnitude events. Investigation of the seasonal suspended load contribution demonstrated\ud that from 1986 to 1993 most fine sediments were transported during the snowmelt/summer seasons,\ud while autumn and snowmelt were the dominant seasons contributing to sediment yield in the periods 1994–\ud 2002 and 2003–2014, respectively. The mean annual sediment yield from 1986 to 2014 is equal to\ud 103 t km−2 yr−1, and overall, bedload accounts for 21% of the total sediment yield. The ratio between the sediment\ud transport and the effective runoff of the events allowed the temporal trends of transport efficiency to be\ud inferred, highlighting the existence of periods characterized by different sediment availability. In particular, despite\ud no significant changes in the hydrological variables (i.e. rainfall), nearly a decade (1994–2002) with high\ud transport efficiency appears to have occurred after an exceptional event (recurrence interval N100 years). This\ud event affected the sediment availability at the basin and channel bed scales, and provided a legacy influencing\ud the sediment dynamics in the basin over the long-term by increasing the transport efficiency for approximately\ud a decade. This work benefits from the long-lasting monitoring program undertaken in the Rio Cordon and is the\ud product of long-term data series. The quasi-unique dataset has provided detailed evidence of sediment dynamics\ud over about three decades in a small Alpine basin, also enabling the effects triggered by an exceptional event to be\ud analyzed

Spatial and temporal scales of occurrence of flash floods, combined with the space and time scales of conventional measurement networks of rain and discharge, make these events particularly difficult to observe. The effective documentation of flash floods requires post-flood survey strategies encompassing accurate radar rainfall estimation, field observations of the geomorphic processes associated with the flood, indirect reconstruction of peak discharges and interviews of eyewitnesses. This paper describes the methods applied and the results achieved in the survey of a flash flood that occurred on 18th September 2007 in the Selška Sora watershed (Western Slovenia). Hydrometeorological analyses of the storm are based on radar reflectivity observations. The documentation of the flash flood reveals high peak flood discharges and a complex flood response. Peak discharges were estimated at 22 cross sections, with drainage areas ranging from 0·2 to 147 km 2 . Among the lessons learned from the field study of the Selška Sora flash flood, there are three key conclusions that can inform similar studies. Firstly, geomorphological surveys are an important prerequisite for flood discharge reconstruction in mountainous watersheds affected by debris flow and intense sediment transport. Secondly, the accounts of eyewitnesses of the flood provide a unique contribution to event reconstruction. Finally, it is necessary to have quality controlled weather radar data, which may permit coupling field observations with rainfall-runoff modelling.

As with most Italian rivers, the Reno River has a long history of human modification, related also to morphological changes of the lower Po River since Roman times, but in the last decades, significant land use changes in the headwaters, dam construction, torrent control works and extensive bed material mining have caused important channel morphology and sediment budget changes. In this paper, two main types of channel adjustment, riverbed incision and channel narrowing, are analysed. Riverbed degradation is discussed by comparing four different longitudinal profiles surveyed in 1928, 1951, 1970 and 1998 in the 120 km long reach upstream of the outlet. The analysis of channel narrowing is carried out by comparing a number of cross-sections surveyed in different years across the same downstream reach. Field sediment transport measurements of seven major floods that occurred between 2003 and 2006 are compared with the bedload transport rates predicted by the most renowned equations. The current low bedload yield is discussed in terms of sediment supply limited conditions due to land use changes, erosion-control works and extensive and out of control bed material mining that have affected the Reno during the last decades