Cross-country comparison of monetary values from SHARELIFE

The SHARELIFE survey contains a set of questions aimed to collect monetary information, such as incomes from work, pension benefits, and house values. Given the retrospective structure of the questionnaire, these amounts refer to different points in time and different currencies. Heterogeneity in time and currencies raises comparability problems: the purpose of this paper is to describe a procedure aimed to generate comparable amounts for the monetary variables in SHARELIFE

Test of methodology for developing a large wood budget: A 1-year example from a regulated gravel bed river following ordinary floods

Wood budgeting is a current approach for quantifying the spatial and temporal variations of in-channel large wood (LW). Despite its importance for a proper LW management, the assessment of LW budget is still a challenge because of the complexity of LW dynamics. Focusing on a 3.7 km-long gravel-bed reach of the Piave River (North-eastern Italy), this study proposes an attempt to assess a short-term (1 year) LW budget as a consequence of ordinary floods (RI < 1 yr). Lateral recruitment, mobilization and deposition of LW were investigated by two field surveys conducted at the beginning and end of the study period. The lateral input was evaluated by measuring, positioning and tagging all standing trees (diameter 65 0.1 m) within a 20 m-wide buffer strip along the floodplain and island perimeters. Bank erosion was checked by measuring the riverbanks with a differential Global Positioning System (dGPS), during the first and second survey. Contemporarily, the position and characteristics of each fluvial wood element (diameter 65 0.1 m and length 65 1 m) within the active channel was determined. These short-term analyses revealed that ordinary floods are not able to induce relevant variations in the LW abundance and redistribution of in-channel wood. Nevertheless, the results highlighted the role of riverbank erosion in supplying LW to the active channel. Episodic inputs of LW from bank erosion were also observed during ordinary flood events, introducing 33% (0.21 m3 \ub7km 121 ) of the total LW input amount. Results on LW transport showed that, in the Piave River, both deposition and mobilization of LW may also occur during low flow conditions (i.e. 14% of bankfull stage) without causing important variations in the wood quantity. However, the low magnitude of floods was reflected in the small amount of LW involved in the input (0.4 m3 \ub7km 121 ) and output (0.7 m3 \ub7km 121 ) processes, pointing out that sites for deposition and mobilization of LW are conditioned by flood magnitude and morphological settings. The combination of recruitment, mobilization and deposition processes resulted in a slight decrease of LW storage ( 120.07%), while including also the anthropic removal of LW the amount of wood storage decreased to 129.7%. Despite the short-term investigation, this work sheds further light on LW processes, providing useful results for the management of LW in wide piedmont rivers

Bedload monitoring in a steep alpine stream: Results from the 2014 measurement campaign

In 2014, three high-frequency flood events (RI=1.1\u20131.7 yr) were investigated both in terms of sediment entrainment and bedload magnitude. The particle displacement was monitored using 250 PITtags installed in the streambed, while the Rio Cordon monitoring station enabled to characterize the bedload transport rate. In terms of displacement a clear difference was observed between the floods investigated. The near-bankfull events showed equal mobility conditions, with mean travel distance one order of magnitude higher respect to what detected in the under-bankfull event. In terms of bedload magnitude, only the near-bankfull events caused transport of coarse material to the monitoring station, depositing 113.0 t and 4.6 t. Both events peaked to 2.06m3s 121 but the bedload differs by more than one order of magnitude, proving that, currently, in the Rio Cordon the bedload appears more related to the sediment supply than to the magnitude of hydrological features

Near-bankfull floods in an Alpine stream: Effects on the sediment mobility and bedload magnitude

In a mountain environment, the transport of coarse material is a key factor for many fields such as geomorphology, ecology, hazard assessment, and reservoir management. Despite this, there have been only a few field investigations of bedload, in particular using multiple monitoring methods. In this sense, attention has frequently focused on the effects of “high magnitude/low frequency floods” rather than on “ordinary events”. This study aims to analyze the sediment dynamics triggered by three high-frequency floods (recurrence interval “RI” between 1.1 and 1.7 yr) that occurred in the Rio Cordon basin during 2014. The flood events were investigated in terms of both sediment mobility and bedload magnitude. The Rio Cordon is an Alpine basin located in northeastern Italy. The catchment has a surface area of 5 km2, ranging between 1763 and 2763 m above sea level. The Rio Cordon flows on an armored streambed layer, with a stable step-pool configuration and large boulders. Since 1986, the basin has been equipped with a permanent station to continuously monitor water discharge and sediment flux. To investigate sediment mobility, 250 PIT-tags were installed in the streambed in 2012. The 2014 floods showed a clear difference in terms of tracer displacement. The near-bankfull events showed equal mobility conditions, with mean travel distance one order of magnitude higher than the below-bankfull event. Furthermore, only the near-bankfull events transported coarse material to the monitoring station. Both events had a peak discharge up to 2.06 m3 s-1, but the bedload transport rates differed by more than one order of magnitude, proving that under the current supply-limited condition, the bedload appears more related to the sediment supply than to the magnitude of the hydrological features. In this sense, the results demonstrated that near-bankfull events can mobilize large amounts of material for long distances, and that floods of apparently similar magnitude may lead to different sediment dynamics, depending on the type and amount of sediment supply

Surprising suspended sediment dynamics of an alpine basin affected by a large infrequent disturbance

In many environments, climate change causes an increase in the frequency and magnitude of Large Infrequent Disturbances (LIDs). LIDs make fragile areas, as mountain basins, even more vulnerable, along with local communities that could be severely affected by extreme events. Among all LIDs, windthrows are one of the most relevant and yet rather unpredictable disturbances affecting the Alpine region. Windthrows can affect the forest cover and morphological settings at the basin scale, changing the supply of sediments to river networks and affecting the sediment cascading processes. This work aims at (i) identifying the contribution of Suspended Sediment Load (SSL) from a windthrow-managed-affected area induced in an Alpine basin by a recent LID (Vaia rainstorm, 2018), (ii) assessing the annual, seasonal and monthly variation in the SSL, and (iii) analysing the changes in SSL fluxes and dynamics in the 2nd and 3rd year after the LID in comparison to those detected after a similar high magnitude event occurred in 1994. To do so, two multiparameter sondes measuring the water level and the turbidity were installed upstream and downstream the windthrow-affected area. Discharge measurements and water samples were collected to obtain the rating curves and calibrate the turbidity meters in order to derive suspended sediment loads (SSL). The results show that the windthrow-affected area was significantly contributing suspended sediment during events occurring two years after Vaia (2020) but less intensively in those occurred three years after the event itself (2021). Both the events average intensity rainfalls and the total precipitation appear to be the best predictors of both the peak of suspended sediment concentration (SSCp), the total suspended sediment (SSL) and the suspended sediment percentage variation among the two cross-sections. The seasonal and monthly analysis revealed to be in line with those detected prior the disturbance. The analyzed LID affected the transport efficiency for near-bankfull events but not the annual sediment yield as it was found after the previous high magnitude flood event recorded in 1994. Unexpectedly, the mean rate of SSL (42 t km -2 yr−1) is indeed comparable with what monitored during the decade before Vaia (2004–2014) (40 t km -2 yr−1). Such surprising results may be explained by the fact that the Rio Cordon basin have had an alluvial response rather than colluvial during the Vaia rainstorm event and that the basin's resilience may be in a different stage as compared to the one of 1994, when the catchment featured different cascading processes that completely overturn the suspended sediment dynamics and fluxes for about a decade

Analysis of Bedload Mobility in an Andean Stream

High gradient streams form the majority of the mountain drainage network and the sediment dynamics that occur here influence the features of sediment deliv-ered downstream. In this sense, the bedload is the transport process that regards the coarser particles, which are mobilized by rolling, sliding, and saltation on the channel bed. In mountain streams, bedload can be the main sediment transport process, there-fore, its analysis and quantification are crucial. However, the importance of bedload contrasts with the fact that it is difficult and impractical to monitor due to its impul-sive nature. Different direct and indirect methods were used during the last decades to cover this gap. One of these is the bedload tracing method. In this work, bedload tracing was used to analyze the sediment dynamics in a high-gradient Andean stream, the Estero Morales, located in central Chile. The Estero Morales stream exhibits an average slope of 14.0% and a D50 = 59 mm. The basin (27 km2) extends between 1780 and 4497 m a.s.l., hosting the San Francisco glacier (1.8 km2) that strongly affects the hydrological regime. In January 2016, 197 clasts tracers were seeded along the Estero Morales stream and their mobility was monitored by 9 surveys between January and March 2016. During this study period, the tracers experienced an average transport distance equal to 12.0 m, while the average diameter mobilized was 95.0 mm. However, the mobility observed was not clearly related to the hydraulic forcing, stressing the complex transport dynamics of a mountain stream

Analisis of Bedload Mobility in an Andean Stream

High gradient streams form the majority of the mountain drainage network and the sediment dynamics that occur here influence the features of sediment delivered to downstream channels, particularly by controlling the timing of sediment fluxes and the amounts and size of material released to the lowland rivers. In this sense, the bedload is the transport process that regards the coarser particles, which are mobilized by rolling, sliding and saltation on the channel bed. In mountain streams, bedload can be the main sediment transport process, particularly, during flood events. Therefore, its analysis and quantification is crucial for several aspects, including hazard assessment, understanding the morphodynamics of higher order channels and managing reservoir sedimentation. However, the importance of bedload contrasts with the fact that it is difficult and impractical to monitor, especially in steep mountain streams, due to its impulsive nature. To cover this gap, different direct and indirect methods were used to investigate the bedload. One of these is the bedload tracing, which starting from the assumption that bedload transport may be understood as the result of random individual particle displacements, permitted to obtain precious data concerning sediment dynamic in mountain streams during the last decades. In this work, bedload was analyzed in an Andean stream by the use of tracing method. The site is the Estero Morales, a high-gradient stream located in the Metropolitan Region (central Chile). The streambed exhibits boulder-cascade, step-pool and plane bed morphologies with an average slope of about 9.5% and a D50 = 59 mm. The basin (27 km2) extends between 3815 and 1850 m a.s.l., hosting the San Francisco glacier (1.8 km2) that strongly affects the hydrological regime. In particular, during the melt period (December-March) the glacier ensures daily discharge fluctuations with highly variable associated bedload transport rates. In January 2016, 197 clasts equipped with Passive Integrated Transponders were seeded along the Estero Morales and their mobility monitored along a reach 745 m long. Specifically, 11 surveys were realized between January and March 2016 using a mobile antenna in conjunction with a laser rangefinder, obtaining a mean recovery rate of 25.9 %. During the study period, the tracers experienced a maximum and mean water discharge equal to 4.28 and 2.59 m3 s-1, respectively. This hydraulic forcing conditions induced the transport up to a maximum diameter of 280.0 mm, while the average diameter mobilized and average transport distance were equal to 95.0 mm and 12.0 m. The mobility observed resulted not clearly related to the hydraulic forcing, stressing the complex transport dynamics of mountain stream

Surprising suspended sediment dynamics of an alpine basin affected by a large infrequent disturbance

In many environments, climate change causes an increase in the frequency and magnitude of Large Infrequent Disturbances (LIDs). LIDs make fragile areas, as mountain basins, even more vulnerable, along with local communities that could be severely affected by extreme events. Among all LIDs, windthrows are one of the most relevant and yet rather unpredictable disturbances affecting the Alpine region. Windthrows can affect the forest cover and morphological settings at the basin scale, changing the supply of sediments to river networks and affecting the sediment cascading processes. This work aims at (i) identifying the contribution of Suspended Sediment Load (SSL) from a windthrow-managed-affected area induced in an Alpine basin by a recent LID (Vaia rainstorm, 2018), (ii) assessing the annual, seasonal and monthly variation in the SSL, and (iii) analysing the changes in SSL fluxes and dynamics in the 2nd and 3rd year after the LID in comparison to those detected after a similar high magnitude event occurred in 1994. To do so, two multiparameter sondes measuring the water level and the turbidity were installed upstream and downstream the windthrow-affected area. Discharge measurements and water samples were collected to obtain the rating curves and calibrate the turbidity meters in order to derive suspended sediment loads (SSL). The results show that the windthrow-affected area was significantly contributing suspended sediment during events occurring two years after Vaia (2020) but less intensively in those occurred three years after the event itself (2021). Both the events average intensity rainfalls and the total precipitation appear to be the best predictors of both the peak of suspended sediment concentration (SSCp), the total suspended sediment (SSL) and the suspended sediment percentage variation among the two cross-sections. The seasonal and monthly analysis revealed to be in line with those detected prior the disturbance. The analyzed LID affected the transport efficiency for near-bankfull events but not the annual sediment yield as it was found after the previous high magnitude flood event recorded in 1994. Unexpectedly, the mean rate of SSL (42 t km -2 yr−1) is indeed comparable with what monitored during the decade before Vaia (2004–2014) (40 t km -2 yr−1). Such surprising results may be explained by the fact that the Rio Cordon basin have had an alluvial response rather than colluvial during the Vaia rainstorm event and that the basin’s resilience may be in a different stage as compared to the one of 1994, when the catchment featured different cascading processes that completely overturn the suspended sediment dynamics and fluxes for about a decade