TY - JOUR A1 - López-Tarazón, José Andrés A1 - Lopez, Pilar A1 - Lobera, Gemma A1 - Batalla Villanueva, Ramon J. T1 - Suspended sediment, carbon and nitrogen transport in a regulated Pyrenean river JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Regulation alters the characteristics of riversty transforming parts of them into lakes, affecting their hydrology and also the physical, chemical, and biological characteristics and dynamics. Reservoirs have proven to be very effective retaining particulate materials, thereby avoiding the downstream transport of suspended sediment and the chemical substances associated with it (e.g. Carbon, C or Nitrogen, N). The study of fluvial transport of C and N is of great interest since river load represents a major link to the global C and N cycles. Moreover, reservoirs are the most important sinks for organic carbon among inland waters and have a potential significance as nitrogen sinks. In this respect, this paper investigates the effects of a Pyrenean reservoir on the runoff, suspended sediment, C and N derived from the highly active Esera and Isabena rivets. Key findings indicate that the reservoir causes a considerable impact on the Esera-Isabena river fluxes, reducing them dramatically as almost all the inputs are retained within the reservoir. Despite the very dry study year (2011-2012), it can be calculated that almost 300,000 t of suspended sediment were deposited into the Barasona Reservoir, from which more than 16,000 were C (i.e. 2200 t as organic C) and 222 t were N. These values may not be seen as remarkable in a wider global context but, assuming that around 30 hm(3) of sediment are currently stored in the reservoir, figures would increase up to ca. 2.6 x 10(6) t of C (i.e. 360,000 t of organic C) and 35,000 t of N. Nevertheless, these values are indicative and should be treated with caution as there is incomplete understanding of all the processes which affect C and N. Further investigation to establish a more complete picture of C and N yields and budgets by monitoring the different processes involved is essential. (C) 2015 Elsevier B.V. All rights reserved. KW - Suspended sediment KW - Carbon KW - Nitrogen KW - Temporal dynamics KW - Barasona Reservoir KW - River Esera KW - Ebro basin Y1 - 2016 U6 - https://doi.org/10.1016/j.scitotenv.2015.06.132 SN - 0048-9697 SN - 1879-1026 VL - 540 SP - 133 EP - 143 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - López-Tarazón, José Andrés A1 - Batalla Villanueva, Ramon J. A1 - Vericat, Damià A1 - Francke, Till T1 - Suspended sediment transport in a highly erodible catchment : the River Isábena (Southern Pyrenees) N2 - Understanding and quantifying sediment load is important in catchments draining highly erodible materials that eventually contribute to siltation of downstream reservoirs. Within this context, the suspended sediment transport and its temporal dynamics have been studied in the River Isabena (445 km(2), south-central Pyrenees, Ebro basin) by means of direct sampling and turbidity recording during a 3-year dry period. The average flood-suspended sediment concentration was 8 g l(-1). with maximum instantaneous values above 350 g l(-1). The high scatter between discharge and suspended sediment concentrations (up to five orders of magnitude) has not permitted the use of rating curve methods to estimate the total load. Interpolation techniques yielded a mean annual sediment load of 184,253 t y(-1) for the study period, with a specific yield of 414 t km(-2) y(-1). This value resembles those reported for small torrents in nearby mountainous environments and is the result of the high connectivity between the badland source areas and stream courses, a fact that maximises sediment conveyance through the catchment. Floods dominated the sediment transport and yield. However, sediment transport was more constant through time than that observed in Mediterranean counterparts; this can be attributed to the role of base flows that entrain fine sediment temporarily stored in the channel and force the river to carry high sediment concentrations (i.e., generally in the order of 0.5 g l(-1)), even under minimum flow conditions. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/0169555X U6 - https://doi.org/10.1016/j.geomorph.2009.03.003 SN - 0169-555X ER - TY - JOUR A1 - Lopez, Pilar A1 - López-Tarazón, José Andrés A1 - Casas-Ruiz, Joan P. A1 - Pompeo, Marcelo A1 - Ordonez, Jaime A1 - Munoz, Isabel T1 - Sediment size distribution and composition in a reservoir affected by severe water level fluctuations JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - The reservoir sediments are important sinks for organic carbon (OC), the OC burial being dependent on two opposite processes, deposition and mineralization. Hence factors such as severe water level fluctuations are expected to influence the rate of OC accumulation as they may affect both deposition and mineralization. The Barasona Reservoir has been historically threatened by siltation, whilst the use of water for irrigation involves a drastic decrease of the water level. In this context, we have studied the physical and chemical characteristics (grain size, major and minor elemental compositions, organic and inorganic carbon, and nitrogen) of the recent sediments of the Barasona Reservoir and the relationships among them in order to: a) elucidate the main processes governing OC accumulation, b) evaluate the rate of OC mineralization and c) approach the effect of drought on the sediment characteristics in this system. Our results indicated that Barasona sediments were dominated by fine silts (>60%) and clays (>20%), the mean particle size decreasing from tail to dam. Desiccation increased particle sorting and size distribution became bimodal, but no effect on average size was observed. Attending to the composition, Barasona sediments were very homogeneous with low concentrations of nitrogen (TN) and phosphorus (<12 g kg(-1) dw and <0.6 g kg(-1) dw, respectively) and high concentration of OC (approximate to 36 kg(-1) dw). TN was negatively related to dry weight Sediment mixing due to drastic changes in water level may have favoured the observed homogeneity of Barasona sediments affecting carbon, major ions and grain size. The high amount of OC deposited in Barasona sediment suggested that the adsorption of OC onto fine particles was more important than in boreal lakes. The rate of oxygen consumption by wet sediment ranged from 2.26 to 3.15 mg O-2 m(-2) day(-1), values close to those compiled for Mediterranean running waters. (C) 2015 Elsevier B.V. All rights reserved. KW - Sediment KW - Grain-size KW - Organic carbon KW - Respiration rate KW - Barasona reservoir KW - Drought Y1 - 2016 U6 - https://doi.org/10.1016/j.scitotenv.2015.06.033 SN - 0048-9697 SN - 1879-1026 VL - 540 SP - 158 EP - 167 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lobera, Gemma A1 - Andres-Domenech, Ignacio A1 - López-Tarazón, José Andrés A1 - Millan-Romero, Pedro A1 - Valles, Francisco A1 - Vericat, Damia A1 - Batalla Villanueva, Ramon J. T1 - Bed disturbance below dams: observations from two Mediterranean rivers JF - Land degradation & development N2 - River-bed disturbance and associated sedimentary processes such as particle mobility are central elements to assess river ecosystem functioning. Dams change river dynamics affecting the magnitude and frequency of biophysical elements that depend on them. This paper examines the effects of two dams different in size, management, and location, on the flow regime, flood competence, and bed disturbance in two contrasting Mediterranean rivers, the Esera and the Siurana. For this purpose, two reaches on each river were monitored upstream and downstream from reservoirs. Several monitoring and modeling techniques were used to characterize flow competence, particle entrainment, and the volumes of sediments eroded and deposited after floods. The flow regime of the Esera has been modified from nivo-pluvial regime, typical of humid mountainous environments, to that observed in dry semiarid regions, in which high magnitude but low frequency floods are the dominant processes. Conversely, the flow regime of the Siurana has changed from a typical Mediterranean stream to a regime observed in more temperate environments, with more permanent and stable flows. Both rivers show notably physical changes, with channels clearly less dynamic below the dams. The lack of competent flows together with the sediment deficit associated with the dams has led to less active fluvial environments (reduced particle mobility and bed scour dynamics), a fact that affects instream habitat structure (more uniform grain size distribution, less physical heterogeneity, more stable flows), overall contributing to the degradation of the stream corridor and the subsequent environmental deterioration of the whole fluvial landscape. Copyright (c) 2017 John Wiley & Sons, Ltd. KW - flow regime KW - dams KW - bed disturbance KW - sediment mobility KW - Mediterranean rivers Y1 - 2017 U6 - https://doi.org/10.1002/ldr.2785 SN - 1085-3278 SN - 1099-145X VL - 28 SP - 2493 EP - 2512 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Lobera, G. A1 - Batalla Villanueva, Ramon J. A1 - Vericat, D. A1 - López-Tarazón, José Andrés A1 - Tena, A. T1 - Sediment transport in two mediterranean regulated rivers JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Mediterranean climate is characterized by highly irregular rainfall patterns with marked differences between wet and dry seasons which lead to highly variable hydrological fluvial regimes. As a result, and in order to ensure water availability and reduce its temporal variability, a high number of large dams were built during the 20th century (more than 3500 located in Mediterranean rivers). Dams modify the flow regime but also interrupt the continuity of sediment transfer along the river network, thereby changing its functioning as an ecosystem. Within this context, the present paper aims to assess the suspended sediment loads and dynamics of two climatically contrasting Mediterranean regulated rivers (i.e. the Esera and Siurana) during a 2-yr period. Key findings indicate that floods were responsible for 92% of the total suspended sediment load in the River Siurana, while this percentage falls to 70% for the Esera, indicating the importance of baseflows on sediment transport in this river. This fact is related to the high sediment availability, with the Esera acting as a non-supply-limited catchment due to the high productivity of the sources (i.e. badlands). In contrast, the Siurana can be considered a supply-limited system due to its low geomorphic activity and reduced sediment availability, with suspended sediment concentration remaining low even for high magnitude flood events. Reservoirs in both rivers reduce sediment load up to 90%, although total runoff is only reduced in the case of the River Esera. A remarkable fact is the change of the hydrological character of the River Lem downstream for the dam, shifting from a humid mountainous river regime to a quasi-invariable pattern, whereas the Siurana experiences the opposite effect, changing from a flashy Mediterranean river to a more constant flow regime below the dam. (C) 2015 Elsevier B.V. All rights reserved. KW - Suspended sediment transport KW - Sediment load KW - Flow regime KW - Barasona Reservoir KW - Siurana Reservoir KW - Ebro basin KW - Mediterranean Y1 - 2016 U6 - https://doi.org/10.1016/j.scitotenv.2015.08.018 SN - 0048-9697 SN - 1879-1026 VL - 540 SP - 101 EP - 113 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fortesa, Josep A1 - García-Comendador, Julian A1 - Calsamiglia, A. A1 - López-Tarazón, José Andrés A1 - Latron, J. A1 - Alorda, B. A1 - Estrany, Joan T1 - Comparison of stage/discharge rating curves derived from different recording systems BT - Consequences for streamflow data and water management in a Mediterranean island JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Obtaining 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. KW - Hydrometric networks KW - Stage-discharge KW - Metering KW - Uncertainty KW - Error propagation Y1 - 2019 U6 - https://doi.org/10.1016/j.scitotenv.2019.02.158 SN - 0048-9697 SN - 1879-1026 VL - 665 SP - 968 EP - 981 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Estrany, Joan A1 - Ruiz, Maurici A1 - Calsamiglia, Aleix A1 - Carriqui, Marc A1 - Garcia-Comendador, Julian A1 - Nadal, Miquel A1 - Fortesa, Josep A1 - López-Tarazón, José Andrés A1 - Medrano, Hipolito A1 - Gago, Jorge T1 - Sediment connectivity linked to vegetation using UAVs BT - High-resolution imagery for ecosystem management JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - In this study, a low-cost unmanned aerial vehicle was used to obtain multi-spectral high-resolution imagery (1.4 cmpx(-1)) from2 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. KW - Ecogeomorphology KW - Mediterranean shrubland KW - Burned areas KW - UAVs KW - BNDVI KW - Sediment connectivity Y1 - 2019 U6 - https://doi.org/10.1016/j.scitotenv.2019.03.399 SN - 0048-9697 SN - 1879-1026 VL - 671 SP - 1192 EP - 1205 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Estrany, Joan A1 - López-Tarazón, José Andrés A1 - Smith, Hugh G. T1 - WILDFIRE EFFECTS ON SUSPENDED SEDIMENT DELIVERY QUANTIFIED USING FALLOUT RADIONUCLIDE TRACERS IN A MEDITERRANEAN CATCHMENT JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - Over short and long timescales, wildfires can be an important cause of hydrological and geomorphological change. Mediterranean rivers are part of a fire-prone and high-energy environment in which the timing of major storms in relation to fire influences the impact on fluvial systems; accordingly, the identification of major sources, stores and fluxes of sediments is essential for providing more effective post-fire management strategies. In this study, caesium-137 and excess lead-210 were used as tracers to quantify the proportional contributions of fine sediment from hillslope surface and channel bank sources to suspended sediment and channel bed deposits before the impact of a forest wildfire in Na Borges, a Mediterranean groundwater-dominated river. It also compared burnt and unburnt spatial sources of sediment within a single catchment and the extent to which burnt material was transported downstream. The study focused on two small and steep sub-catchments, where just one of the catchments was partially affected by a wildfire. The pre-fire dynamics indicated that surface soils were the main sediment source in these ephemeral creeks. Post-fire sediment dynamics were characterised by a single flood event with a short recurrence interval (i.e. return period ca. <1 year). Sediment generated from the burnt area contributed 12% on average to bed-stored sediments within the burnt catchment, which reduced downstream to 5% along the main channel of the Na Borges River. The findings demonstrate the potential for using fallout radionuclide tracers to understand the wider impacts of wildfires on fluvial environments located outside of the burn area. Copyright (C) 2015 John Wiley & Sons, Ltd. KW - wildfire KW - sediment delivery processes KW - sediment source fingerprinting KW - fallout radionuclides KW - Mediterranean fluvial systems Y1 - 2016 U6 - https://doi.org/10.1002/ldr.2462 SN - 1085-3278 SN - 1099-145X VL - 27 SP - 1501 EP - 1512 PB - Wiley CY - Hoboken ER -