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Even before Italica was founded by the Romans at the end of the third century BC, this settlement maintained a close relationship with the morpho-dynamic evolution of the lower Guadalquivir river (SW Andalusia, Spain), especially with the lateral channel displacements. In order to reconstruct the palaeogeographic evolution of the alluvial area of Itálica during the second half of the Holocene, our research has focused on the study of the fluvial paleoforms and the alluvial soil-sedimentary sequence, with special emphasis on the analysis of the geoarchaeological records. Ancient maps and aerial photographs of various scales and diverse dates have been interpreted. Borehole cores and profiles, manually or mechanically opened, have also been done to obtain samples for laboratory tests of the representative floodplain soils and sediments. The chronologies provided by the archaeological record were completed with several radiocarbon dates. From these results we propose a possible solution at a local level to the traditional discussion about the existence and location of the ancient harbour of Italica; and for the alluvial plain as a whole, a double alternating palaeogeographic sequence trending to millennial-submillennial scale has been reached. The first one occurring controlled by hydrologic and climatic factors, modulated by a prolonged and extended human pressure on the basin, and showing a succession of four main stages characterized by the predominance of alluvial filling (4833-3206 cal BP; 3130-1989 cal BP; 1620 cal BP-XI century AD; and around the last 500 years), which are separated by periods of stability that favored alluvial soils formation; meanwhile, the second sequence presents short-time terms prone to riverbed design shifting (period prior to Late Bronze; Roman-republican era; central Middle Age), also separated by lengthy phases of morpho-hydrographic stability. In the latter case the main factor does not seem to be, as in the first of those, hydro-climatic shifts and land use changes, but rather the last small regional fluctuations of sea level that came with the second part of the Holocene.

Approximate methods to populate dark-matter haloes with galaxies are of great utility to galaxy surveys. However, the limitations of simple halo occupation models (HODs) preclude a full use of small-scale galaxy clustering data and call for more sophisticated models. We study two galaxy populations, luminous red galaxies (LRGs) and star-forming emission-line galaxies (ELGs), at two epochs, z = 1 and z = 0, in the large-volume, high-resolution hydrodynamical simulation of the MillenniumTNG project. In a partner study we concentrated on the small-scale, one-halo regime down to r ∼ 0.1 h−1 Mpc, while here we focus on modelling galaxy assembly bias in the two-halo regime, r ≳ 1 h−1 Mpc. Interestingly, the ELG signal exhibits scale dependence out to relatively large scales (r ∼ 20 h−1 Mpc), implying that the linear bias approximation for this tracer is invalid on these scales, contrary to common assumptions. The 10–15 per cent discrepancy is only reconciled when we augment our halo occupation model with a dependence on extrinsic halo properties (‘shear’ being the best-performing one) rather than intrinsic ones (e.g. concentration, peak mass). We argue that this fact constitutes evidence for two-halo galaxy conformity. Including tertiary assembly bias (i.e. a property beyond mass and ‘shear’) is not an essential requirement for reconciling the galaxy assembly bias signal of LRGs, but the combination of external and internal properties is beneficial for recovering ELG the clustering. We find that centrals in low-mass haloes dominate the assembly bias signal of both populations. Finally, we explore the predictions of our model for higher order statistics such as nearest neighbour counts. The latter supplies additional information about galaxy assembly bias and can be used to break degeneracies between halo model parameters.

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Se modela el comportamiento del nivel piezométrico intraanual de la laguna Charco del Toro (Parque Nacional de Doñana, Huelva, España) mediante técnicas de análisis multivariante. El propósito del trabajo es doble: por una parte, interpretar el comportamiento actual del nivel piezométrico de la laguna a partir de diferentes variables ambientales y, por otra, realizar predicciones ante el cambio climático para finales del siglo XXI. Aunque la aproximación metodológica para ambos tipos de modelos es semejante, basada en el análisis de regresión lineal multivariante, los modelos elaborados para cada uno de los propósitos fueron diferentes, debido a la mayor disponibilidad de datos para variables ambientales en el pasado reciente, que de predicciones con suficiente precisión sobre variables ambientales en el futuro. Los resultados obtenidos del modelo explicativo del funcionamiento actual de la laguna indican que el comportamiento del nivel piezométrico depende esencialmente de la precipitación acumulada durante periodos de tiempo largos (de 6 a 10 meses) antes del momento de estudio, así como de la evapotranspiración potencial registrada en los 10 meses anteriores. Los modelos elaborados para predecir el comportamiento intraanual futuro, a partir de diferentes escenarios y modelos climáticos, sugieren que el nivel piezométrico de la laguna descenderá drásticamente (entre 1 y 1,5 metros por debajo de los niveles actuales), independientemente del modelo de cambio climático y del escenario de emisiones asumido.