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Purpose: Identifying best practices for sediment fingerprinting or tracing is important to allow the quantification of sediment contributions from catchment sources. Although sediment fingerprinting has been applied with reasonable success, the deployment of this method remains associated with many issues and limitations. Methods: Seminars and debates were organised during a 4-day Thematic School in October 2021 to come up with concrete suggestions to improve the design and implementation of tracing methods. Results: First, we suggest a better use of geomorphological information to improve study design. Researchers are invited to scrutinise all the knowledge available on the catchment of interest, and to obtain multiple lines of evidence regarding sediment source contributions. Second, we think that scientific knowledge could be improved with local knowledge and we propose a scale of participation describing different levels of involvement of locals in research. Third, we recommend the use of state-of-the-art sediment tracing protocols to conduct sampling, deal with particle size, and examine data before modelling and accounting for the hydro-meteorological context under investigation. Fourth, we promote best practices in modelling, including the importance of running multiple models, selecting appropriate tracers, and reporting on model errors and uncertainty. Fifth, we suggest best practices to share tracing data and samples, which will increase the visibility of the fingerprinting technique in geoscience. Sixth, we suggest that a better formulation of hypotheses could improve our knowledge about erosion and sediment transport processes in a more unified way. Conclusion: With the suggested improvements, sediment fingerprinting, which is interdisciplinary in nature, could play a major role to meet the current and future challenges associated with global change. [ABSTRACT FROM AUTHOR]

Soil erosion and sediment transport are controlled by complex factors promoting variable responses in catchment's erosion rates and sediment yields. To mitigate eventual negative effects derived from altered fluxes, integrated catchment management plans should assess the sediment cascade from upstream erosive processes, sediment mobilization through hillslopes and within the channel, up to downstream sediment yields. This study links hydro-sedimentary dynamics with sediment fingerprinting source ascription in a mid-mountainous Mediterranean catchment during five hydrological years (2013–2018). Soil colour parameters and fallout radionuclides were used as tracers to predict dominant suspended sediment sources using (i) a Bayesian mixing model (MixSIAR) and (ii) an End Member Mixing Analysis (EMMA). MixSIAR suggested that crops were the dominant source in most of the collected samples. EMMA showed similar results, clustering all except one sediment samples close to the crop and channel bank signatures. In addition, a quantitative hysteresis index was calculated and floods were clustered in function of their hydro-sedimentary characteristics. Despite different patterns were associated to each of the four identified clusters (e.g. different sediment loads and maximum suspended sediment concentrations), correlation between sediment origin and hydro-sedimentary variables was not significant due to the little seasonal variation in source type ascription. • Combination of continuous water and sediment monitoring with sediment fingerprinting were tested as catchment management tools. • The MixSIAR Bayesian mixing model and End Member Mixing Analysis showed similar results. • End Member Mixing Analysis provided valuable insights to determine dominant suspended sediment sources. • Source ascription homogeneity did not allow the link of hydro-sedimentary response to sediment source contributions. [ABSTRACT FROM AUTHOR]

The influence of the sea and topography are vital factors in the atmospheric processes affecting any island, as they introduce peculiarities in the hydrosedimentary response of fluvial systems. In view of that, the relationship between the surface atmospheric conditions (weather types, WTs), rainfall, runoff and erosion dynamics in three small catchments located in Mallorca were analysed. The catchments are representative in terms of geomorphology and land use but also due to their location within the major rainfall areas previously identified in the island by (Sumner et al., 1993). Data of rainfall, runoff and sediment variables, coupled with calculated WTs were used for the 2013–2017 period. WTs frequency and distribution during this period were compared to the last climatic period reference (1981–2010) to test the climate validity of the study period. The results illustrated how hydrosedimentary response was mostly caused by eco-geographical patterns but also by differences in the response of each catchment to WTs, related to the intrinsic geographical position in the island and different exposures to humid winds. Anticyclonic WT was the most frequent, despite it being only involved in one flood event at the eastern catchment. Conversely, eastern and northeastern WTs generated more than 85% of the total runoff and sediment, representing only 39% of flood events. The understanding of the specific role of WTs on the island's hydrology was improved, considering that freshwater resources are scarce and eco-sociologically crucial. • Weather types, rainfall, and hydrosedimentary assessment in a Mediterranean island. • Three small contrasting catchments located in different rainfall areas of Mallorca. • Eastern and northeastern weather types generated >85% of runoff and sediment. • Low runoff and erosion values in Mediterranean standards by karstic features. • Sediment transport was extremely ephemeral due low frequency of easterly flows. [ABSTRACT FROM AUTHOR]

Soil moisture conditions play a key role in runoff and sediment load dynamics in river catchments of contrasting ecosystems. However, the highly marked seasonality of Mediterranean climate affects hydrological processes and sediment transport strongly, as evapotranspiration determines a succession of wet, transition and dry periods throughout a hydrological year. This study examines results of soil moisture, water and sediment fluxes during five hydrological years in a representative small mid-mountain Mediterranean catchment. It aims to assess the sediment load contribution and its variability at different temporal scales. Precipitation, runoff and suspended sediment load were calculated at annual, seasonal and event scales to assess inter- and intra-annual variability. A database with 45 events was used to identify the main controlling factors over sediment load thought bivariate relationships and an analysis of soil moisture-discharge and discharge-suspended sediment concentration hysteresis. At the annual scale, lithology, land use and soil conservation structures characteristic of the catchment caused low values of sediment yield, although inter-annual rates varied by up to three orders of magnitude (0.08 to 11.86 t km−2 y−1). Seasonal analysis of accumulated sediment load showed that 80% was generated during the autumn and winter seasons. At the event scale, streamflow and soil moisture were the controlling factors for the largest sediment load contributions. The highest frequency of clockwise discharge-suspended sediment concentration hysteresis revealed that most of the sediment was generated from nearby sources, although the largest sediment loads were contributed under wet antecedent conditions, as depicted by the soil moisture-discharge hysteresis assessment. • Physical and anthropic catchment features promoted low sediment load. • Soil moisture content explained runoff and sediment load dynamics. • Soil moisture and discharge are controlling factors of sediment load. • Soil moisture hysteresis determined sediment load dynamics under wet antecedent conditions. • Counter-clockwise discharge-sediment hysteresis when catchment is hydrologically connected [ABSTRACT FROM AUTHOR]