Articles publicats (Química, Física i Ciències Ambientals i del Sòl)

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    Open Access
    Evaluation of 2D hydrodynamic-based rainfall/runoff modelling for soil erosion assessment at a seasonal scale
    (Elsevier, 2024) Costabile, Pierfranco; Cea, Luis; Barbaro, Gabriele; Costanzo, Carmelina; Llena, Manel; Vericat Querol, Damià
    Badlands are often the source of a significant fraction of the sediment reaching the river network due to the exposure of the bare soil to the impact of rain drops and to the bed shear stress generated by the surface runoff. Hence, a correct understanding of the soil erosion and sediment transport processes inside badlands can help to a better characterisation of the suspended sediment production at the catchment scale. In this work we study the suitability of a two-dimensional (2D) physically-based event-scale erosion model as a tool to represent soil erosion and sediment transport in badlands at a seasonal scale. The model solves the 2D shallow water equations, including infiltration and rainfall, in order to compute the generation and routing of surface runoff within the badland. Coupled to the hydrodynamic equations, the model solves a 2D suspended sediment transport equation with source terms that account for rainfall- and runoff-driven erosion and sediment deposition. Based on this model, an overall procedure was developed and tested considering, as case study, a badland located in El Soto catchment (central Pyrenees, Iberian Peninsula). For the analysed badland, several high-resolution topography surveys were available, which allowed for the estimation of the soil loss and the spatial distribution of erosion patterns for periods of 3–4 months over two years. These data sets were used to calibrate and validate the proposed modelling approach, and to analyse its capabilities and limitations for the assessment of soil erosion at the seasonal scale.
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    Open Access
    Factors affecting mobility/export of particle-bound stable elements after erosive rainfalls in agroforestry Mediterranean catchments of Aragón (Spain)
    (Elsevier, 2024) Ramos Martín, Ma. C. (Ma. Concepción); Lizaga, Iván; Gaspar, Leticia; Catalá, Arturo; Navas, Ana
    The composition of sediment fluxes caused by erosion can vary greatly both spatially and temporally, causing different impacts on water bodies. The erosion process is mainly driven by soil and rainfall characteristics as well as land use. The aim of this research is to evaluate the combined effect of these factors in a mountain agroforestry system, analysing the relationship of the sediment composition generated after flooding events with soil and rainfall characteristics and the impact of land use. The analyses were based on data recorded in three catchments with Mediterranean climate. The sediments were collected after 21 seasonal campaigns and their characteristics were assessed taking into account rainfall characteristics and the main land uses in each catchment. The results confirm the differences in soil particle mobilization after high and low intensity events and the higher impact of croplands compared to other dominant land uses. The amount of sediments trapped in the catchment with the largest area of cropland almost doubled sediment collected in the other catchments. Clay and soil organic carbon in the sediments were lower than in the original sources, likely due to the lower content in the soils more susceptible to erosion and the washing out of the finer material by runoff under high amount/intensity precipitation. Differences were observed between catchments and between rainfall events in the export of stable elements, with a general sediment enrichment in Al, Be, B, Cu, Mn, S, Sr and Zn, reaching the highest values for Be, Sr and Zn. The elemental enrichment differed according to rainfall characteristics thus Cu, Zn or Mn were higher after low intensity events, while other elements like Be were enriched after high intensity events. These variable patterns evidence the complex interplay of involved factors and the key role of elemental bounds to particle sizes and organic matter.
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    Open Access
    Retrieving the irrigation actually applied at district scale: assimilating high-resolution Sentinel-1-derived soil moisture data into a FAO-56-based model
    (Elsevier, 2024) Laluet, Pierre; Olivera-Guerra, Luis Enrique; Altés, Víctor; Paolini, Giovanni; Ouaadi, Nadia; Rivalland, Vincent; Jarlan, Lionel; Villar Mir, Josep Ma.; Merlin, Olivier
    Irrigation is the most water consuming activity in the world. Knowing the timing and amount of irrigation that is actually applied is therefore fundamental for water managers. However, this information is rarely available at all scales and is subject to large uncertainties due to the wide variety of existing agricultural practices and associated irrigation regimes (full irrigation, deficit irrigation, or over-irrigation). To fill this gap, we propose a two-step approach based on 15 m resolution Sentinel-1 (S1) surface soil moisture (SSM) data to retrieve the actual irrigation at the weekly scale over an entire irrigation district. In a first step, the S1-derived SSM is assimilated into a FAO-56-based crop water balance model (SAMIR) to retrieve for each crop type both the irrigation amount (Idose) and the soil moisture threshold (SMthreshold) at which irrigation is triggered. To do this, a particle filter method is implemented, with particles reset each month to provide time-varying SMthreshold and Idose. In a second step, the retrieved SMthreshold and Idose values are used as input to SAMIR to estimate the weekly irrigation and its uncertainty. The assimilation approach (SSM-ASSIM) is tested over the 8000 hectare Algerri-Balaguer irrigation district located in northeastern Spain, where in situ irrigation data integrating the whole district are available at the weekly scale during 2019. For evaluation, the performance of SSM-ASSIM is compared with that of the default FAO-56 irrigation module (called FAO56-DEF), which sets the SMthreshold to the critical soil moisture value and systematically fills the soil reservoir for each irrigation event. In 2019, with an observed annual irrigation of 687 mm, SSM-ASSIM (FAO56-DEF) shows a root mean square deviation between retrieved and in situ irrigation of 6.7 (8.8) mm week-1, a bias of +0.3 (−1.4) mm week-1, and a Pearson correlation coefficient of 0.88 (0.78). The SSM-ASSIM approach shows great potential for retrieving the weekly water use over extended areas for any irrigation regime, including over-irrigation.
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    Open Access
    Source areas and paleoenvironmental reconstruction of the Serra d'Almenara loess (NE Ebro Valley, Iberian Peninsula) from grain-size and heavy mineral signatures
    (Elsevier, 2024) Plata Moreno, José Manuel; Balasch Solanes, J. Carles (Josep Carles); Boixadera Llobet, Jaume; Baltiérrez, Antoni; Preusser, Frank; Poch, Rosa M.
    The northeastern part of the Ebro Basin (NE Spain) features loess that cover an area of about 40 km2 on the northern slopes of the Serra d'Almenara anticline. The deposits and soils developed from them were mapped, described, and dated by luminescence. Additionally, grain size, percentage of heavy minerals (>2.8 g/cm3), and the mineralogical composition of the heaviest fraction (>3.2 g/cm3) were analysed. The coarse textures of the deposits indicate a very proximal origin. Therefore, potential source areas of the sands and silts were analysed with special attention given to the extensive river floodplains and alluvial fans close by, as well as gypsum-rich rocky outcrops. The mineral signature of the loess shows that it mainly originates from the alluvial plain of the Segre River, located about 10–30 km to the west. In some places, the loess also received particles from the alluvial fans of the Ondara and Corb rivers located south of the Almenara reliefs. In addition, the gypsum present in the loess is apparently derived from Eocene deposits. The loess in the study area was deposited during cold phases of the last two glacial cycles when the topographic obstacle of the Serra d'Almenara blocked the dominant winds from the southwest. Analysis of the almost 4-meter-thick profile of Pilar d'Almenara shows initial but limited accumulation phases in Marine Isotope Stages (MIS) 6, followed by the formation of a red soil during MIS 5e. Accumulation resumed during MIS3, with more energetic and powerful wind transport during the final phase of MIS 3 (ca. 34–30 ka) and early MIS 2, but prior to the Last Glacial Maximum. Our data highlights the prominent role of large rivers and alluvial fans as the sources of particles that are later reworked by the wind.
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    Open Access
    Ammonia volatilization from pig slurries in a semiarid agricultural rainfed area
    (MDPI, 2023) Jiménez de Santiago, Diana Elisa; Ovejero, Jonatan; Antúnez Pujol, Montserrat; Bosch Serra, Àngela D.
    Slurries are one of the main NH3 emission sources. Nitrogen losses impact air quality, and they constrain the sustainability of farming activities. In a rainfed Mediterranean agricultural system, the aim was to quantify NH3 emissions at a time when plants do not yet cover the soil surface and according to fertilization practices. One treatment was slurry from fattening pigs (PSF) applied before cereal sowing and incorporated into the soil; two treatments were PSF or from sows (PSS) applied at the cereal tillering stage (topdressing); and two more treatments received slurries twice, before sowing and as topdressing. Ammonia emissions were quantified with semi-static chambers during 145 h (before sowing) and 576 h (at cereal tillering) after slurry application. Before sowing, tillage after slurry application controlled NH3-N emissions, but they accounted for 14% of the total NH4-N applied. At tillering, average NH3-N emissions also accounted for ca. 14% of total NH4-N applied as PSF or PSS, respectively. Slurry dry matter from 84 kg m-3 (PSS) up to 127 kg m-3 (PSF), combined with low soil moisture content (below 30% of water holding capacity) at application time, helped in NH3 emission control. Slurry applications before sowing did not enhance later NH3-N emissions at topdressing.