Articles publicats (Grup de Recerca de Dinàmica Fluvial (RIUS))
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- ItemOpen AccessPatterns of nutrients and algal biomass in an intermittent Mediterranean river under intense human activity(Elsevier, 2025) Córdoba-Ariza, Gabriela; Muñoz-Mas, Rafael; Batalla, Ramon J.; Mas-Pla, Josep; Sabater, SergiNon-perennial streams are often affected by human activities such as sewage water disposal and agriculture. The limited capacity of these systems to dilute pollutants, along with the extent of water flow interruption, leads to a high variability of nutrient concentrations and algal biomass, with relevant implications for water quality. The temporal and spatial patterns of nutrients—Total Nitrogen (TN), Nitrates (NO3-), Total Phosphorus (TP), and Phosphates (PO43-)—and chlorophyll (as a surrogate of algal biomass) were characterized in a Mediterranean river system to determine their relationship to water flow intermittency and human activities. To achieve this, monthly measurements of water quality, physicochemical characteristics and algal biomass were collected at 23 different locations over 14 months, coinciding with the onset of drought conditions in the region. Random forest regression and the model-agnostic SHapley Additive exPlanations (SHAP) enabled us to identify the most influential hydrological and land use features for nutrient concentrations and map the spatial variation of their effects across the basin. The highest variability in nutrient concentrations occurred in the headwaters, while high values consistently occurred in the middle and lower segments. While TN and NO3- sources were diffuse, mainly agriculture, TP and PO43- levels were determined by the number of effluent point sources. Overall, water flow intermittency was not a strong predictor of nutrient patterns; however, its influence was more pronounced at specific sites. Applying the same modeling approach, we identified that suspended chlorophyll levels (but not benthic chlorophyll) correlated with nutrient concentrations, showing a notable association to TP and seasonal variations in precipitation and temperature. Our analysis underscores the complex interactions between hydrology, human activities, and nutrient dynamics in river basins subjected to water flow intermittency and highlights the need for management strategies focused on local polluted points.
- ItemOpen AccessComparison of stage/discharge rating curves derived from different recording systems: consequences for streamflow data and water management in a Mediterranean island(Elsevier, 2019) Fortesa, J.; García-Comendador, J.; Calsamiglia, A.; López Tarazón, José Andrés; Latron, J.; Alorda, B.; Estrany, JoanObtaining representative hydrometric values is essential for characterizing extreme events, hydrological dynamics and detecting possible changes on the long-term hydrology. Reliability of streamflow data requires a temporal continuity and a maintenance of the gauging stations, which data are affected by epistemic and random sources of error. An assessment of discharge meterings' and stage-discharge rating curves' uncertainties were carried out by comparing the accuracy of the measuring instruments of two different hydrometric networks (i.e., one analogical and one digital) established in the same river location at the Mediterranean island of Mallorca. Furthermore, the effects of such uncertainties were assessed on the hydrological dynamics, considering the significant global change impacts beset this island. Evaluation was developed at four representative gauging stations of the hydrographic network with analogic (≈40 years) and digital (≈10 years) data series. The study revealed that the largest source of uncertainty in the analogical (28 to 274%) and in the digital (17–37%) networks were the stage-discharge rating curves. Their impact on the water resources was also evaluated at the event and annual scales, resulting in an average difference of water yields of 183% and 142% respectively. Such improvement on the comprehension of hydrometric networks uncertainties will dramatically benefit the interpretation of the long-term streamflow by providing better insights into the hydrologic and flood hazard planning, management and modelling.
- ItemOpen AccessGeomorphic adjustments to multi-scale disturbances in a mountain river: A century of observations(Elsevier, 2020-04-03) Llena Hernando, Manel; Vericat Querol, Damià; Martínez Casasnovas, José Antonio; Smith, Mark W.In this paper we analyse the geomorphic response of a mountain river (Upper Cinca River, Central Southern Pyrenees) in relation to multi-scale disturbances during almost a century (i.e., 1927–2015). The integration of multiple geomorphic descriptors (i.e., morphology and topography) and disturbances (i.e., floods, land use changes, dams, embankments and gravel mining activities) allows better understanding of the cause-effect relations and their significance. The paper presents a novel methodology integrating the application of SfM-MVS algorithms to historical imagery to extract multitemporal channel topography and morphology; and the use of statistical tools to infer on the existence of significant trends and breakpoints in the temporal evolution of the geomorphic descriptors and disturbances. Results show that afforestation was the main land use change exhibited between 1957 and 2015, although mainly concentrated during 1977–2015. Annual runoff presented a general negative trend with a wet (1959–1983) and dry period (1983–2015). Extensive gravel mining occurred after flood events, together with channel engineering works such as the construction of embankments. These disturbances, together with the construction of three small dams in the headwaters, had a direct impact on lateral connectivity by confining and constraining channels and concentrating flows, resulting inchannel incision and stability. The evolution of the disturbances, process changes and geomorphic descriptors indicated that, during the last century, the river channel is in a transient state, in which the magnitude of the changes oscillate. The river is adjusting to the disequilibrium imposed by multi-scale disturbances acting at different temporal and spatial scales by means of two contrasting channel states. First, Channel State 1 (1927–1984) was characterised by having high geomorphic activity and channel incision. Conversely, Channel State 2 (1984–2015) was characterised, by having a low geomorphic activity, when channel constraining was the dominant process and incision was more localised and marginal. The results of the Upper Cinca may be relevant to infer in future fluvial metamorphosis associated with the effects of global change on water and sediment fluxes in mountain catchments, and to assist objective-based rehabilitation measures of rivers subjected to multi-scale disturbances.
- ItemOpen AccessAn R-based integrated method for producing river bathymetry and cross-sections from recreational-grade sonar sensor data(Elsevier, 2024) Redana, M.; Carrero‐Carralero, EstrellaWater bodies’ bathymetry is a crucial information for understanding and sustainably managing water resources. Bathymetric surveys can be expensive due to sonar equipment cost, but low-cost alternatives options exist. We present a methodology that standardize the bathymetric data collection and processing of recreational-grade sonar data. The sonar data postprocessing if fully implemented in R, with ready to use functions able to produce bathymetric maps or extract river cross sections’ metrics with minimal computing efforts. The method robustly produces a variety of outputs; the performance of the equipment adopted and of the interpolation technique allow for high accuracy and low-cost bathymetric reconstruction. • The method implemented allow for a robust and consistent processing of recreational-grade sonar water depth measures. • Through R-based functions the data are postprocessed to obtain bathymetry maps also for complex shape waterbodies. • Further metrics of rivers/channel cross sections can be extracted.
- ItemOpen AccessInferring on fluvial resilience from multi-temporal high-resolution topography and geomorphic unit diversity(Elsevier, 2024) Llena Hernando, Manel; Batalla, Ramon J.; Vericat Querol, DamiàThe resilience of a river corridor represents its ability to withstand and recover from disturbances. Quantifying fluvial resilience in the face of various stressors is essential for integrating ecology and geomorphology in a context of river management. Geomorphic unit diversity analysis emerges as a valuable tool for characterizing and quantifying fluvial resilience to disturbances due to its inherent connection with fluvial dynamics. This paper aims to analyse and quantify the fluvial resilience of a wandering gravel-bed river affected by natural (e.g., floods) and human-induced (e.g., instream gravel mining) stressors. To achieve this goal, we use multi-temporal high-resolution topographic surveys of the Upper River Cinca (South-Central Pyrenees) spanning from 2014 to 2020. By employing the Geomorphic Unit Tool (GUT) on these surveys, we can map geomorphic units over time, quantify their diversity, and study geomorphic adjustments through morphodynamic signatures, altogether allowing inferring fluvial resilience. Our findings reveal that topographic changes (i.e., erosion and sedimentation) correlate with the type of stressor: maintenance works and gravel mining lead to degradation, while floods induce aggradation. Geomorphic Unit Diversity decreases following channel disturbances caused by gravel mining but rebounds after periods primarily stressed by floods, returning to pre-impact levels within six years. Geomorphic adjustments, such as channel incision and mid bar development, reflect erosion and sedimentation processes respectively, with channel maintenance works and floods being the main drivers. Despite the recovery of the geomorphic unit diversity within the reach, the deficit resulting from gravel extraction remains unresolved, perpetuating a degrading trend that poses risks in reducing lateral connectivity and could potentially catalyse future vegetation encroachment in bars and floodplains, causing changes on flood conveyance and hydraulics. Monitoring the river's geomorphic diversity provides crucial insights for effective conservation and management decisions regarding land use, development, and conservation along riverbanks, thereby sustaining or enhancing fluvial system resilience.