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• Alteration of sediment properties during transport and storage in a temporary stream. • The spatial variability of soil properties was higher than the in-channel variability. • Colour properties showed the highest temporal and spatial stability. • Results are relevant for future sediment fingerprinting studies. Soil properties used as tracers in sediment fingerprinting studies are assumed to remain stable or vary in a predictable way in their transfer from sources to sinks, allowing a comparison with suspended sediment properties. Attention to the conservative behaviour of soil properties has largely focused on the differences in the particle size and organic matter content between sources and target sediments. However, in-channel biochemical alterations are also known to occur, and their magnitude is still poorly understood. An experiment to investigate the in-channel variations of soil properties during transport and storage was carried out with the most common soil properties used as tracers in sediment fingerprinting studies (i.e. colour, fallout radionuclides and geochemical elements). Twenty-eight soil samples collected from different land uses were introduced into an intermittent stream channel of a small Mediterranean catchment. Samples were recovered at different time intervals over one year. The changes in soil properties (average coefficient of variation 8.1 ± 8.8 %) were generally lower than the spatial variability of each source within the catchment (average coefficient of variation 16.3 ± 18.5 %). No significant differences were observed between samples from different land use types or when recovered at different time intervals. Soil properties that showed higher in-channel coefficients of variation were S, 137Cs, 210Pb ex , As, Mo and Na, with annual coefficients of variation > 19 %. Conversely, carbon (C) and colour properties were the most stable in time (average coefficient of variation 2.1 ± 0.4 % and 2.6 ± 2.2 %, respectively). The results presented will be informative with regard to performing future suspended sediment fingerprinting studies in Mediterranean catchments, providing a better understanding of which soil properties are more sensitive to in-channel biochemical alterations. [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]

• Colour parameters tracing suspended sediment sources after a wildfire. • Scanner and spectrometer derived colour tracers showed a high correlation. • Ash content discriminated burned and unburned sources. • Colour and fallout radionuclides provided analogous results. After a wildfire, total or partial removal of vegetal biomass and changes in physicochemical soil properties lead to an increase in overland flow and sediment yield. Eventual damage must be counteracted urgently by identifying erosion hotspots and by implementing post-fire management programmes and sampling campaigns. In this context, the sediment source fingerprinting technique is widely used to determine the origin of suspended sediments in catchments and to evaluate the effectiveness of sediment management programmes. It traditionally relies on the use of physical, biochemical and geochemical properties as tracers. However, measuring these tracers in the laboratory is often expensive and time-consuming. Colour tracers have been shown to greatly reduce time and cost, especially if a normal office scanner is used for measurements. Here we explored whether colour parameters can be used to investigate suspended sediment origin in burned catchments. To this end, sediment and ash were mixed artificially to verify colour linear additivity and ash influence on colour parameters. Colour parameters were then used for source ascription of suspended sediment samples (n = 9) collected during two years after a fire in a small Mediterranean catchment (Mallorca, Spain). In addition, reflectance-derived colour parameters were compared with those obtained using a normal office scanner. The close correlation between most chromatic indexes (obtained using both methods; p < 0.01) suggested that scanning is a good alternative for measuring soil and sediment colour. A Bayesian tracer mixing model (MixSIAR) determined the relative contribution of each source. The type of mixing model enables appropriate representation of natural and sampling uncertainty in tracer data. During the first events, suspended sediment originated mainly in burned surfaces, whereas the contribution of these decreased throughout the study period. Tracing results obtained using colour parameters were compared with calculations using 137Cs and 210Pb ex , as recognized tracers to discriminate between surface and subsurface sediment sources after wildfires. Estimated source ascriptions with both methods (i.e. reflectance-derived colour parameters and radionuclides) coincided in predicting the dominant source in 7 of the 9 samples measured. Colour tracers proved useful in discriminating between burned and unburned sources, making them suitable for suspended sediment source ascription and monitoring as part of post-fire management strategies. [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]

• Hydrology and sediment transport were compared in two intermittent rivers. • Lithology influenced the degree of flow intermittence more than rainfall. • Flow regime was the most relevant factor affecting sediment yield. • In Búger River, SSY was related to antecedent rainfall and peak discharge. • In Carapelle River, SSY was related to amount and intensity of rainfall. Flow and the sediment regime affect water quality and nutrient delivery in all river systems and are fundamental in sustaining the river ecosystem. This study aims to identify the most relevant factors affecting the flow regime and the suspended sediment transport in two Mediterranean intermittent rivers: the Búger (Spain) and the Carapelle (Italy). A set of hydrological indicators were used to characterize and classify the flow regime. High-resolution data, streamflow and suspended sediment concentration were used to quantify runoff and sediment yields at different temporal scales (annual, monthly, event). Rainfall, streamflow and sediment variables were used at the event scale to assess the rainfall-runoff-suspended sediment relationship through the Pearson correlation matrix. Hysteresis analysis provided information on sediment source dynamics. In the Búger River, the high degree of flow intermittence was mainly due to the presence of carbonate lithology and forest land use at headwaters promoting low values of runoff coefficient (2–10%) and specific suspended sediment yield (SSY; 0.5–46 t km−2 y−1). In the Carapelle River, the high values of annual runoff coefficient (14–35%), together with low flow intermittence and SSY (89–745 t km−2 y−1) were related to clay and flyschoid lithology. Most of the annual sediment yield (SY, t) was transported during floods. In Búger, SSY and maximum suspended sediment concentration (SSC max, g l−1) were checked against runoff, peak discharge and antecedent rainfall. In Carapelle, SSY and SSC max were checked against the amount and intensity of rainfall. The catchment size and the spatial distribution of rainfall, land uses and lithology played important roles in the flow regime, suspended sediment transport and hysteretic behaviour. Characterization of the flow regime linked to its main physical drivers improved understanding of the hydrological response and sediment transport variability of intermittent rivers. This study provided valuable insights into water resource management, improving the prediction of spatial patterns and of the intensity of sediment transport in river basins. [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]

In this study, a low-cost unmanned aerial vehicle was used to obtain multi-spectral high-resolution imagery (1.4 cm px−1) from 2 microcatchments (3.3 ha) with burned Mediterranean shrubland and pine forests. This imagery was used to calculate the blue normalized differential vegetation index and to generate digital elevation models for estimating the sediment connectivity index. Both indices enabled an integrated approach for deciphering how hydrological and sediment connectivity interact with vegetation as well as soil conservation structures. The application of spatial analysis improves our understanding of the feedback between biological and geomorphological processes. Local spatial data analysis established a significant link between local geomorphological and biological factors, enabling a precise identification of homogeneous areas at micro-catchment scale and the minimal size of vegetation units reacting to geomorphology as natural groups at plot-scale where management strategies and efforts should be applied. Establishing this local relationship between sediment connectivity and vegetation patterns through new and interdisciplinary methodologies represents a new strategy for the assessment of ecosystem dynamics and management. Unlabelled Image • Very high-resolution multi-spectral imagery are used to generate HR-DEM models. • Relations between sediment connectivity and post-disturbance vegetation dynamics are mapped. • Spatial data established significant links between local bio-geomorphological factors. • Hotspot areas where management strategies should be applied are identified. [ABSTRACT FROM AUTHOR]

Mediterranean humid mountains are ecological hotspots with high water availability that may accelerate their recovery after farmland abandonment, a widespread phenomenon in marginal areas of the European Mediterranean Region. This land use change led to secondary succession processes triggering changes in soil properties and soil microorganisms. This is the first study in assessing the environmental influence of both ecological succession and parent material over soil properties and soil bacterial communities in these habitats. To examine the effects of secondary succession and elucidate the role of parent material in soil bacterial communities, six soil plots were sampled from the combination of abandoned and rainfed olive groves, terraced or non-terraced, and over four parent materials in Lluc Valley, a Mediterranean hyper-humid mountainous area on the island of Mallorca, Spain. Soil bacterial diversity and taxonomic composition at phylum and family level in each field were analyzed by rRNA 16 S amplicon sequencing. In addition, a series of soil physicochemical and microbiological properties, together with enzyme activities were assessed. Results showed that secondary succession and parent material significantly affected soil physicochemical and microbiological properties, soil enzyme activities and soil bacterial communities' diversity and taxonomic composition. Secondary succession following farmland abandonment triggered higher total organic carbon (TOC), microbial biomass carbon (C mic), basal soil respiration (REB), alkaline phosphatase activity (Php) and dehydrogenase activity (DHA), thus enhancing soil quality. In contrast, parent material significantly shaped pH, specific surface area (SSA), TOC, C mic , REB and soil enzyme activities, playing a key role in land use effects modulation. According to the distance-based redundancy analysis (db-RDA), SSA, TOC, REB, C mic , urease activity (Ur) and Php were the soil properties that contributed to significant changes in bacterial communities' composition at the family level. This study evidenced that farmland abandonment led to improve soil quality in Mediterranean humid mountains, with positive feedbacks provided by parent material. • Farmland abandonment triggered higher TOC, C mic and REB, enhancing soil quality. • Lithology significantly shaped pH, SSA, TOC, C mic , REB and soil enzyme activities. • β-diversity analyses showed changes due to secondary succession and parent material. • Significant relationships were found between soil properties and bacterial families. [ABSTRACT FROM AUTHOR]

Accurate representation of both artificial elements (e.g. agricultural terraces, drainage channels, roads) and naturally dominant geomorphological landscape features (e.g. rock outcrops, topographical depressions) in digital terrain models (DTMs) is considered as a major requirement for catchment hydro-geomorphological modelling in Mediterranean areas. In fact, in Mediterranean landscapes –as in other geographic regions– human activities have significantly altered catchment hydro-sedimentological functioning. Thus, the actual patterns of hydro-sedimentological connectivity observed within a landscape may largely differ from the spatial organization of water and sediment fluxes that could be expected under the original, natural state of the system.We studied the terrain representation of human-made structures and naturally dominant landscape features for two high-resolution LiDAR DTMs (5 and 1-m spatial resolution) and two medium-resolution satellite-derived DTMs (ASTER GDEM V2 and SRTM C-SAR V3 DEM, ~30-m spatial resolution) along three small (3-5 km2) catchments and nested small-detail (50-ha) plots. Ground reference elevation data was collected using a real-time kinematic GPS, basic terrain descriptors such as the slope-area relationship were computed and a recently developed spatial index of surface flow connectivity (IC) was applied. The study areas –located in the Island of Mallorca, Spain– are characterized by land-use and geomorphological patterns that are representative for most Mediterranean environments, providing a suited framework for assessing the applicability of DTM in catchment hydro-sedimentological modelling.The two studied LiDAR-based models and SRTM data showed in general a good agreement of modelled stream network as well as water and sediment flow patterns, while the large vertical inaccuracy (up to 16-m RMSE) and coarse ground sampling distance of the ASTER data largely limited its applicability for revealing surface patterns. Small-detail features (e.g. agricultural terraces, preferential flow patterns), however, were only captured by the high-resolution LiDAR models, thereby emphasizing the need for high spatial resolution (<5 m) data in hydro-sedimentological modelling. Meter to sub-meter wide features -such as artificial drainage channels- were underrepresented even for the 1-m model. In fact, the ability of high-resolution LiDAR-based terrain models to capture fine-grained catchment hydro-sedimentological connectivity can be considerably constrained where underlying point cloud density does not match the spatial scale of hydrologically determinant landscape features. The applied index of connectivity was revealed as a powerful tool for assessing the representation of dominant landscape features in DTM datasets and further catchment hydro-sedimentological modelling. [ABSTRACT FROM AUTHOR]

Digital terrain models (DTMs) are a fundamental source of information in Earth sciences. DTM-based studies, however, can contain remarkable biases if limitations and inaccuracies in these models are disregarded. In this work, four freely available datasets, including Shuttle Radar Topography Mission C-Band Synthetic Aperture Radar (SRTM C-SAR V3 DEM), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Map (ASTER GDEM V2), and two nationwide airborne light detection and ranging (LiDAR)-derived DTMs (at 5-m and 1-m spatial resolution, respectively) were analysed in three geomorphologically contrasting, small (3–5 km2) catchments located in Mediterranean landscapes under intensive human influence (Mallorca Island, Spain). Vertical accuracy as well as the influence of each dataset's characteristics on hydrological and geomorphological modelling applicability were assessed by using ground-truth data, classic geometric and morphometric parameters, and a recently proposed index of sediment connectivity. Overall vertical accuracy—expressed as the root mean squared error (RMSE) and normalised median deviation (NMAD)—revealed the highest accuracy for the 1-m (RMSE = 1.55 m; NMAD = 0.44 m) and 5-m LiDAR DTMs (RMSE = 1.73 m; NMAD = 0.84 m). Vertical accuracy of the SRTM data was lower (RMSE = 6.98 m; NMAD = 5.27 m), but considerably higher than for the ASTER data (RMSE = 16.10 m; NMAD = 11.23 m). All datasets were affected by systematic distortions. Propagation of these errors and coarse horizontal resolution caused negative impacts on flow routing, stream network, and catchment delineation, and to a lower extent, on the distribution of slope values. These limitations should be carefully considered when applying DTMs for catchment hydrogeomorphological modelling. [ABSTRACT FROM AUTHOR]