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Permanent grasslands cover 34% of the European Union's agricultural area and are vital for a wide variety of ecosystem services essential for our society. Over recent decades, the permanent grassland area has declined and land use change continues to threaten its extent. Simultaneously, the management intensity of permanent grasslands increased. We performed a systematic literature review on the multifunctionality of permanent grasslands in Europe, examining the effects of land use and management on 19 grassland ecosystem service indicators. Based on the evidence in 696 out of 70,456 screened papers, published since 1980, we found that both land use change and intensification of management decreased multifunctionality. In particular, preventing conversion of permanent grasslands to croplands secured the delivery of multiple ecosystem services. A lower management intensity was associated with benefits for biodiversity, climate regulation and water purification, but impacted the provision of high-quality animal feed. Increasing the number of species in the sward enhanced multifunctionality of permanent grassland without significant trade-offs such as losses in production. Our review covered many aspects of land use, management and ecosystem services, but we also identified areas with no or only few studies. The most prominent gaps were related to comparisons between permanent and temporary grasslands, and effects of management practices on the provision of cultural values, and on erosion and flood control. We suggest that, despite apparent changes in human dietary preferences, the protection of permanent grasslands in Europe must be prioritised. At the same time, considering the need to reduce ruminant livestock's contribution to climate change, the time seems ripe to increase support for low-intensity grassland management to optimise the provision of essential ecosystem services from Europe's permanent grasslands.

Permanent grasslands cover 34% of the European Union’s agricultural area and are vital for the delivery of essential ecosystem services. Over recent decades, permanent grasslands have suffered a significant decline and land use change continues to threaten their area. We performed a systematic review on the multifunctionality of permanent grasslands in Europe, examining the effects of land use change and management practices on 18 ecosystem service indicators. Based on the evidence in 696 out of 70,456 screened papers, we found that both land use change and intensification decreased multifunctionality. A lower management intensity was associated with benefits for biodiversity, climate regulation and water purification, but had a negative effect on the provision of high-quality animal feed. Increasing the number of species in the sward enhanced multifunctionality of permanent grassland without significant trade-offs such as losses in production. We suggest that a combined approach of protection and management extensification will help secure multiple benefits from permanent grasslands.

Grassland research stations and experimental farms are essential for applied grassland science and related outreach activities. A large proportion of the experiments conducted at these stations aims to test methods to optimize the ecosystem services (ES) delivered by permanent grasslands. We used the framework of the multi-actor research project SUPER-G to assess a selection of experiments recently conducted, completed (since 2011), and planned at 31 European experimental research stations, farms, or networks. We further provide an overview of the ES measured at these experiments. Results show that on average two ES were assessed per experiment. The most frequent ES measured were production (87% of all experiments), followed by the supporting ES biodiversity (59%) and climate regulation (33%). Our overview on ES research at European research stations highlights that permanent grassland is a multifunctional ecosystem that provides many benefits to society. Yet, research considering more than two ES is still relatively rare and should thus be strengthened in the future.

Trabajo presentado en el 8th International Symposium on Gully Erosion, celebrado en Townsville (Australia) del 21 al 27 de julio de 2019., Erosion associated with concentrated flow in Mediterranean cultivated areas is considered as a major process of land degradation. In this work, the features of rills and ephemeral gullies generated in an olive orchard catchment of [.C ha, where tillage operations were usually applied, were measured and compared with sediment loads at the catchment outlet. The specific objectives were: ) to quantify the rills and ephemeral gullies measured in the catchment for inter-tillage periods where different hydrological features (precipitation and erosivity) and management schemes were observed; and O) to assess the contribution of concentrated flow to measured sediment discharge at the catchment outlet by considering the impact of cover crop strips during the last period.

Postprint de la versión final de manuscrito aceptado en revista., Lateral transfer of organic carbon and phosphorus by water erosion at hillslope scale can be a key component in understanding their budget in agricultural areas, particularly those located in areas where erosion rates are high. In this study dissolved organic carbon (DOC) and dissolved reactive phosphorus (DRP) in runoff, and organic carbon (OC) and total phosphorus (TP) in sediment were measured in three olive orchards. These measurements were carried out in a three year runoff plots trial under two different soil management systems (temporary cover crop in the lanes, CC, and conventional tillage, CT). DOC losses (7.8–13.6 kg ha-1 yr-1) were equivalent, and OC losses (101–432 kg ha-1 yr-1) were higher than those measured in other agricultural and forest systems. Thus, both sources of OC, dissolved in runoff and in sediment, should not be neglected as a relevant flux to water bodies in the region and in the soil organic carbon (SOC) balance at hillslope scale. Losses of DRP (0.03–0.21 kg ha-1 yr-1) were in the lower to medium range of published values in agricultural areas, while losses of TP in sediment (2–39 kg ha-1 yr-1) were in the higher range of those reported form agricultural areas in the Mediterranean region, as the combined result of enrichment in sediment and high sediment losses. There is the scope for a large reduction of TP by reducing sediment losses through appropriate CC management. Average annual concentration of DOC in runoff and OC and TP in sediment was correlated with that of the top 5 cm of the soil in the lanes of the orchards. When analyzed at event scale, in DOC, OC and DRP presented a moderated trend towards a larger concentration for runoff events of low magnitude, below 10 to 20% runoff coefficient approximately. However, these trends at event scale presented a large scattering that precludes the determination of robust correlations for prediction and model calibration purposes., Project P08-AGR-03643, P12-AGR-931 (Andalusian Government) and FEDER funds (European Unión). The long term experiment at Benacazón was also supported by Syngenta through project BIOSUELO.

Póster presentado en la Conferencia ELS 2014, 22-25 Septiembre 2014, Bari, Italia In spite of the great effort of scientific research exploring the influence of agricultural practices on soil quality, many aspects remain unclear, possibly precluding a more general adoption of the best management systems by farmers and land use planners. Among other causes of this knowledge gap, the wide variety of agricultural practices due to different climates, landforms, soils, and crop types make hard to find either a general best management system or at least common rules of larger applicability. Nevertheless the more important problem is that we usually consider soil as an invariant entity which does not change, or if it does, its changes are controlled. The purpose of this report is the discussion of the results of a meta-analysis of the effects of agricultural management practices on physical aspects of soil quality, throughout the published research data of countries of the central and western part of the European continent. Soil physical quality was evaluated through several indicators which were evaluated in the research reports found. The indicators were: bulk density, resistance to penetration, stability of aggregates, permeability and water and sediment yield. The results indicate that there are agricultural practices which could be classified as convenient, although their possible advantages are not always evident, as, for instance, direct drilling as compared to conventional tillage, where the farm operations induce a certain compaction not always alleviated in absence of tillage. To further explore some of the results, the evolution of some properties of a clay soil subject to a long term experiment in dry farming conditions in southern Spain is considered. The evolution of the soil properties must be taken into account, for a more precise evaluation of the efficiency of management practices.

Póster presentado en la Conferencia EGU 2013, 07-12 Abril 2013, Viena, Austria Soil has a key role in the regulation of carbon, water and nutrient cycles. Traditionally, agricultural soil management was oriented towards optimizing productivity. Nowadays, mitigation of climate change effects and maintaining long-term soil quality are evenly important. Developing policy guidelines for best management practices need to be site-specific, given the large spatial variability of environmental conditions within the EU. Therefore, it is necessary to classify the different farming zones that are susceptible to soil degradation. Especially in Mediterranean areas, this variability and its susceptibility to degradation is higher than in other areas of the EU. The objective of this study is therefore to delineate current agro-environmental zones in Spain and to determine the effect of global climate change on this classification in the future. The final objective is to assist policy makers in scenario analysis with respect to soil conservation. Our classification scheme is based on soil, topography and climate (seasonal temperature and rainfall) variables. We calculated slope and elevation based on a SRTM-derived DEM, soil texture was extracted from the European Soil Database and seasonal mean, minimum and maximum precipitation and temperature data were gridded from publically available weather station data (Aemet). Global change scenarios are average downscaled ensemble predictions for the emission scenarios A2 and B2. The k-means method was used for classification of the 10 km x 10 km gridded variables. Using the before-mentioned input variables, the optimal number of agro-environmental zones we obtained is 8. The classification corresponds well with the observed distribution of farming typologies in Spain. The advantage of this method is that it is a simple, objective method which uses only readily available, public data. As such, its extrapolation to other countries of the EU is straightforward. Finally, it presents a tool for policy makers to assess the impact of global change on farming systems and to plan soil conservation measures.

Póster presentado el Día de la Conservación del Suelo 2013

Trabajo presentado en la EGU General Assembly 2016 (European Geosciences Union), celebrada en Viena del 17 al 22 de abril de 2016.

Las estructuras viarias, al modificar las condiciones naturales del terreno, para suavizar trazado y pendiente, generan unos desmontes y terraplenes que dejan superficies de suelo o roca desprotegidos y con gran riesgo de erosión. Este manual parte de los resultados del proyecto “Estabilización biotécnica de taludes: optimización de tratamientos en proyectos de restauración paisajística de infraestructuras viarias en Andalucía”, desarrollado para la Consejería de Fomento y Vivienda, y subvencionado con fondos FEDER pretende mostrar un conjunto de criterios básicos con ejemplos de aplicación para ayudar a los profesionales en la toma de decisiones para el control de erosión desde la fase de diseño hasta la ejecución de actuaciones en obra civil., Agencia de Obra Pública de la Junta de Andalucía. Consejería Fomento y Vivienda. Junta de Andalucía. y Fondos FEDER. A través de Proyecto: G-GI3000/IDIS2014.

Trabajo presentado en la EGU General Assembly 2016 (European Geosciences Union), celebrada en Viena del 12 al 17 de abril de 2015., The rational use of soil requires the selection of management practices to take profit of the beneficial functions of plant growth, water and nutrient storage, and pollutants removal by filtering and decomposition without altering its properties. However, the first evidence of important and widespread erosion peaks can generally be found with the arrival of the first farmers all over the world. In areas with a long land-use history such as the Mediterranean, clear signs indicating the advanced degradation status of the landscape, such as heavily truncated soils, are visible throughout. Soil conservation practices are then aimed at reducing erosion to geological rates, in equilibrium with long-term soil formation rates, while maximizing agricultural production. The adoption of such practices in most areas of the world are as old as the earliest soil erosion episodes themselves. This work firstly reviews historical evidence linking soil management and soil erosion intensity, with examples from N Europe and the Mediterranean. In particular, work by the authors in olive orchards will be presented that shows how significant variations in soil erosion rates between could be linked to the historical soil management. The potential of historical documents for calibrating a soil erosion model is shown as the model, in this case RUSLE-based and combining tillage and water erosion, adequately represents the measured erosion rate dynamics. Secondly, results from present-day, long-term farm experiments in the EU are reviewed to evaluate the effect of different soil management practices on physical soil properties, such as bulk density, penetration resistance, aggregate stability, runoff coefficient or sediment yield. Finally, we reflect upon model and field data that indicate how future global climate change is expected to affect soil management and erosion and how the examples used above hold clues about sustainable historical management practices that can be used successfully in the future.

Trabajo presentado en la EGU General Assembly 2014 (European Geosciences Union), celebrada en Viena del 27 de abril al 2 de mayo de 2014., Linear infrastructures, such as highways and railways, present a large environmental impact. Among this impact is the effect on landscape and the modification of the hydrological conditions of the area and an increase in erosive processes (Martin et al., 2011). The increase of erosive processes is specially significant in roadbanks, resulting in high maintenance costs as well as security risks for the use of the infrastructure if it is not properly controlled. Among roadbanks, roadcuts are specially challenging areas for erosion control and ecological restoration, due to their usually steep slope gradient and poor conditions for establishment of vegetation. There are several studies in Mediterranean conditions indicating how the combination of semiarid conditions with, sporadic, intense rainfall events makes a successful vegetation development and erosion control in motorway roadbanks extremely difficult (e.g. Andrés and Jorbat, 2000; Bochet and García-Fayos, 2004). This communication presents the results of the first year evaluation (hydrological year 2012-2013) of five different erosion control strategies on six different locations under different materials on roadcuts of motorways or railways in Andalusia during 2012-2013 using natural rainfall and simulated rainfall. The six sites were located on roadcuts between 10 and 20 m long on slope steepness ranging from 40 to 90%, in motorways and railways spread over different materials in Andalusia. Site 1, Huelva was located on consolidated sand material, sites 2, Osuna I, site 3, Osuna II and site 4, Mancha Real, on marls. Sites 5, Guadix, and 6, Fiñana, were located on phyllites, in comparison a harder material. At each site 12 plots (10 m long and 2 m wide) were installed using metal sheets buried 10 cm within the soil with their longest side in the direction of the roadcut maximum slope. Six different treatments were evaluated at each site, two replications each. These treatments were: 1- A control with bare soil, 2-Hydroseeding with a mix of grasses and legumes adapted for Mediterranean conditions, 3- Plantation of Mediterranean shrub species at a 1 plant m-2 density, 4- organic erosion control mat (made of coconut or esparto grass, Stipa tenacissima, fiber) plus hydroseeding. 5- synthetic net mat for erosion control plus hydroseeding. 6- synthetic 3D-net mat for erosion control plus hydroseeding. All the plots had an outlet with routed runoff and sediment to a sediment trap located at the base of the roadcut. The treatments were installed during early fall 2012. Since that date sediments were regularly collected and the evolution of vegetation was monitored. In four of the sites (the other two were vandalized) rainfall simulation experiments using a mesoplot rainfall simulator based on Sumner et al. (1996) were performed in summer 2013. The evaluation of vegetation cover and number of plants made in May, at the end of the rainy season, indi- cated how the hydroseeding treatments (the three mats plus the hydroseeding without mat) presented a relatively high ground cover (between 25 to 35 %) but with a relatively large standard deviation (around 25%). This variability was clearly related to site features (slope, parent material, and climate conditions for the year) with no clear differences among treatments. The plantation and control treatments presented a much lower ground cover, as expected, ranging, in average, from 5 to 10%. There was a large variability in the pattern of plant distribution within the plots, with site to site differences. So in sites 1, 2 and 5 there was a trend towards increased plant density in the lower area of the plot while in site 3 this trend was reversed and in sites 4 and 6 there was not a clear pattern., Sediment lost during the rainfall period, which ranged from 294 to 778 mm from October 1st to May 31st, presented a large variability among sites with maximum values ranging from 2.5 g m-2 (Fiñana) to 1800 (Mancha real). In all the sites there was a clear difference between the mat treatments which presented very low erosion rates, with an average for all sites and the three mat treatments around 4 g m-2, compared to the non-matted treatments which presented much higher erosion rates, average of all sites and three non-matted treatments around 432 g m-2.. There were no significant differences among the different treatments within these two large groups, albeit in some sites a slight reduction in the average erosion rates was observed in the hydroseeding treatment compared to the control and plantation treatments. Simulation experiments performed during summer indicated no runoff generation in the Fiñana site (the one with the lowest sediment generated during the rainy season with an average of 0.7 g m-2), while in the Mancha Real, Huelva and Guadix sites, the results were qualitatively comparable with those observed during the rainfall period with natural rain. The matted treatments presented average sediment losses of 16 g m-2 (for rainfall simulations lasting 35 minutes and an rainfall intensity of 34 mm h-1), while the non-matted treatments averaged sediment losses of 2297 g m-2. The range of maximum sediment losses among sites varied this time in relation to the natural rainfall results with maximum values measured in the Huelva and Guadix sites. The results indicates that effective erosion control in these roadcuts under mostly sedimentary material and Mediterranean conditions was achieved only using erosion mats plus hydroseeding. The protection was achieved mostly by the protective effect of the erosion mats, as indicated by The rainfall simulation experiments highlighted the protective effect of the erosion mats when most of the vegetation was already dead., In addition, there were no apparent with not clear differences during this first year among the different matting materials. Hydroseeding and plantation were apparently successful during the first season, with a significant ground cover and plant density.; However the success of vegetation establishment can only be evaluated in the coming years, since previous experiences (e.g. Bochet and García-Fayos, 2004) indicates the difficulty of successful vegetation recovery on these conditions. Rainfall simulations have proven to be a useful tool to evaluate erosion risk and performance of the different treatments in a shorter time.

Trabajo presentado en el ELS 2014 Conference ("The Earth Living Skin: Soil, Life and Climate Changes", celebrada en Castellaneta (Italia) del 22 al 25 de septiembre de 2014., Soil losses caused by rills, ephemeral gullies and gullies represent one of the major processes of land degradation in agricultural areas such as olive orchards, where the interaction of steep slopes, frequent erosive rainfall events, low soil cover and inappropriate managements contribute to their development. The identification of dominant erosive phenomena in agricultural fields are essential for the design and implementation of suitable management strategies.

Póster presentado en la European Geosciences Union General Assembly, celebrada en Viena del 7 al 12 de abril de 2013., In olive grove land-uses, most studies of soil losses have been conducted to quantify inter-rill erosion at the plot scale or the total sediment load, at the catchment scale. However, work carried out on others land uses in the Mediterranean area have justified that the description of soil losses resulting from concentrated flow is essential since it can jeopardise production and sustainability of commercial farms (e.g. De Santisteban et al., 2006; Castillo, 2012). In this work, measurements of gullies and rills have been done in an olive orchard microcatchment of 6.1 ha during three years (Jul-2010, Jul-2011 and Jul-2012). No tillage management allowing the development of a grass spontaneous cover was applied in the study period. Moreover, data of rainfall, runoff and sediment load in the catchment outlet were measured. The objectives of this study were: 1) the quantification of the erosion by concentrated flow in the catchment for hydrological years with different features; 2) as well as the description of the morphological changes (width, depth, drainage area and slope) in rills and gullies associated to the annual climate regime and management operations.

Trabajo presentado en la European Geosciences Union General Assembly, celebrada en Viena del 7 al 12 de abril de 2013., Soil organic carbon (SOC) shows a considerable spatial variability at the field, farm or catchment scales. This complicates its use as an indicator for soil quality, and is an important drawback for the efficient evaluation of carbon sequestration schemes, or for the certification of carbon sequestration potential of agricultural soils at these scales. This is especially significant for olive orchards in Mediterranean environments. We hypothesize that the typical row crop configuration of olive orchards, with cover crops or bare soil in the inter-row areas,can explain a vast proportion of this variability. In addition agricultural activities and topography-driven erosion processes at different scales contribute to SOC variability. Given the complexity of this problem and the important experimental effort required to address it, there are to our knowledgefew studies that have addressed this issue, specifically in agriculturalsoils under Mediterranean conditions. We present an analysis of SOC data obtained during 2011 and 2012 at three small (6-8 ha) catchmentsin Southern Spain, with contrasting soils (Vertisol, Luvisol and Cambisol) and covered by olive groves with different managements (conventional tillage, minimum tillage with mulch and non tillage with spontaneous grass cover). Soil organic carbon is analysed across tree rows, inter-row areas, and for different depths. The spatial SOC distribution is evaluated against the topography of the catchments and the intensity of the water erosion processes. The differences among the catchments are discussed and guidelines are provided for further exploring the sources of SOC variability and to improve SOC estimation at the field scale.

Este manual resume los criterios básicos para el diseño y reparación de estructuras para control de cárcavas, revegetación y muros de retención en paisajes agrarios. Va dirigido a técnicos y agricultores., Dirección General de Producción Agraria. Junta de Andalucía. Proyectos P08-AGR-03925 (financiado por la Junta de Andalucía), AGL2009-12936-C03-01 (financiado por el Ministerio de Ciencia e Innovación), la red RESEL (financiada por el Ministerio de Medio Ambiente, Rural y Marino), fondos FEDER y el Programa de Diversificación del Paisaje del Ayuntamiento de Córdoba

6 páginaws, 4 fotos, 4 gráficos., Este artículo presenta un resumen de los resultados de un programa de ensayos desarrollado en colaboración con la compañia Syngenta, que durante los últimos años ha medido la erosión y la escorrentía en un olivar de verdeo en el Aljarafe sevillano, así como de medidas complementarias como pérdidas de nutrientes, materia orgánica y biodiversidad de las cubiertas (esto último de manera incipiente)., Este trabajo ha recibido el apoyo continuado de Symgenta desde sus inicios en el año 2002 a través de los proyectos ProTerra I y II y Biosuelo. Desde el año 2009 algunas medidas adicionales han sido posible gracias a los proyectos P08-AGR-03643 RESEL y fondos FEDER.

La variabilidad climática en zonas tropicales suramericanas, combinada con la creciente intervención humana del suelo tiene gran incidencia en los procesos de producción y transporte de sedimentos, que no son bien conocidos en la región. Por lo tanto, se han analizado detalladamente estos procesos en los 393 km2 de la cuenca del río Tonusco, tributaria del río Cauca en Colombia, usando información edáfica, climática y de vegetación. Los cambios en la erosividad de la lluvia y la cobertura vegetal del suelo se estimaron a partir de los datos de precipitación y del índice de la diferencia de la vegetación normalizada, procedente de imágenes satelitales adquiridas entre 1977 y 2015. Con esto se obtuvieron las pérdidas de suelo que se relacionaron con la carga de sedimentos medida. Así se elaboró un modelo de estimación de la aportación de sedimento a la red fluvial. Las pérdidas de suelo fueron severas en algunas regiones (>120 Mg ha-1año-1) y, además, se detectó un incremento durante la última década, asociado a una reducción del 50% de la superficie de bosque, y a la mayor intensidad de la lluvia recibida durante los fenómenos de El Niño, La Niña y la oscilación del Sur, ENSO. Se calculó que entre el 2.0% y 50% de la masa de sedimentos producidos son arrastrados fuera de la cuenca. Se consideraron también las contribuciones de sedimentos generados en los deslizamientos de ladera que representan entre el 0.0% y el 6.3% de la producción total, analizando diferentes episodios ocurridos en la cuenca con la ayuda de modelos para predecir su probabilidad de ocurrencia y magnitud. Por último, se detectaron ciclos de histéresis en las relaciones entre la descarga líquida y sólida del río, causados por la interacción de los procesos limitantes de la erosión, bien por la disponibilidad de sedimentos o bien por la capacidad de su transporte por el agua. Esto permitió identificar las características de la erosión del suelo en la cuenca. The climate variability of tropical Southamerican region, together with enhanced land cover changes caused by the human intervention greatly modify sediment production and transport processes. The effects on sediment dynamics is not very well known so far. Therefore, this dissertation explored these processes in the Tonusco river watershed in the tropical southwestern slopes of the Andean range (Colombia) using edaphic, topographic, and vegetative information, as well as the liquid and solid daily discharge recorded at the outlet. The rainfall erosivity and cover vegetation changes were evaluated from the rainfall records obtained from the watershed rain gauges, and the Normalized Difference Vegetation Index values obtained from satellite images, during the 1977-2015 period. Once the potential soil loss rate of the watershed was computed using an adapted form of the RUSLE model, the sediment routing-based delivery ratio was estimated with another adaption of the SEDD model, that was calibrated and validated with data from sediment loads recorded at the basin outlet. According to results, the vegetation cover of the whole catchment has been reduced to a half during the last decade. Soil erosion rates were locally very high (>120 Mg ha-1yr-1), with relevant peaks during the La Niña ENSO events. Sediment yields were estimated at the range of 2.0%- 50% of total sediment production. Frequents landslide events occurring in the mountain slopes were quantified using several models that predicted their probability. The landslide model was calibrated with data recorded in 36 landslide events of basin. Finally, the hysteresis cycles detected in the relationships between liquid and solid discharges were analysed comparing sediment and runoff travel times.

La sequía agrometeorológica o agrícola es una de las más graves contingencias a la que se enfrenta la agricultura y por tanto la sociedad en su conjunto, ya que se define en términos de pérdida de cosecha provocando escasez de alimentos. A su vez, la sequía es la amenaza de origen natural que afecta a más personas en el conjunto del planeta. La mayoría de los estudios sobre sequía no cuantifican de manera fiable su efecto sobre la productividad agrícola ni abordan las consecuencias de las predicciones de cambio climático sobre la extensión y la intensidad de las sequías. Una buena comprensión y el desarrollo de modelos adecuados de predicción de ocurrencia de sequías a escala tanto a corto como a medio plazo es esencial para una adecuada gestión de los recursos hídricos y de la producción agrícola. Asimismo, se pueden obtener importantes beneficios de mejorar la vigilancia y la predicción a largo plazo de las sequías, para lo que es fundamental tener en cuenta las proyecciones de escenarios de cambio climático. En esta tesis se han aplicado por primera vez los indicadores de estrés de sequía estático y dinámico propuestos por Porporato, validándolos frente a datos observados de rendimiento de cultivos, para evaluar sequías agrícolas a escala local. Se identificaron correctamente los periodos de sequía ocurridos poniendo de manifiesto su gran utilidad y se demostró que ambos indicadores presentan mejores resultados que los indicadores tradicionales de sequía como el SPI-3. Se realizó un análisis de sensibilidad revelando el impacto de la profundidad del suelo en las variaciones espaciales de los indicadores, presentando una respuesta compleja en función de la precipitación anual. En la tesis se propone un nuevo indicador combinado de sequía (ICS), que se evaluó a escala regional frente a datos observados de daños en cultivos de cereales en secano, identificando correctamente los eventos importantes de sequía acaecidos. Se ha diseñado un sistema de avisos de situaciones de sequía agrícola a partir del ICS basado en la combinación de sus componentes, que invita a poner en marcha las medidas oportunas para paliar los efectos de la sequía. Por otro lado, se han modelado los efectos del cambio climático sobre los eventos de sequía a escala nacional hasta 2100, empleando el escenario de emisión RCP8.5. Se mostraron las ventajas, frente a otros indicadores, del empleo de los indicadores de estrés estático y dinámico, teniendo este último la ventaja respecto a otros indicadores de incluir, además de la intensidad, información sobre la duración media y la frecuencia de los eventos de sequía en un único indicador. Los resultados obtenidos mostraron que los indicadores propuestos por Porporato identifican correctamente los periodos de sequía ocurridos en las zonas de estudio y presentan mejores resultados que los indicadores tradicionales de sequía. Por otro lado, los resultados demostraron que el ICS propuesto presenta consistencia con los eventos de sequía agrícola ocurridos en la región de estudio y presenta potencial para servir como indicador de avisos de sequía agrícola futura además de proporcionar distintas ventajas respecto al uso de indicadores simples. Por último, los resultados determinaron que tanto la severidad como la frecuencia y la intensidad de las sequías se verán incrementadas en el escenario RCP8.5 en nuestro país, en particular en el subperiodo 2071-2100.

Premio extraordinario de Trabajo Fin de Máster curso 2016-2017. Máster en Hidráulica Ambiental Irrigation with reclaimed water from the olive table industry is an alternative source of water for semi-arid areas, as long as salinity does not affect seriously soil quality. Appropriate water management can be studied through modelling. The objective of this project is to study the potential of the APEX model to evaluate the evolution of salinity in soils irrigated with reclaimed water. Different irrigation doses with different salt concentrations are analyzed for three different types of soils (Sandy Loam, Silty Loam, Silty Clay Loam). The results show significant differences in soil salinity, ranging between 0,60 ± 0,02 and 12,57 ± 0,38 dS m-1. The soil quality limit is 6 dS m-1, this value is exceeded with some of simulated conditions, one of theses it is when salt concentration in irrigation water is 3840 ppm. The main conclusion of this study is that the APEX model is a suitable tool as it could be adapted successfully to take into account these scenarios for olive orchards.

Gully erosion is widely recognised as an important soil degradation process in many regions, causing important on-site (e.g. soil losses, environmental degradation, crop losses...) and off-site effects (e.g. muddy floods, water pollution, reservoir siltation...). In contrast to other erosion processes, as for instance sheet and rill erosion, where models have been successfully developed and tested extensively over the world, no widely accepted model exists for gully erosion. The reasons for this are the varied and complex subprocesses involved in gully erosion, the factors that control it and, its dependence on the spatial and temporal scale of study. Notwithstanding the above, gully erosion has been proved to be the major erosion process contributing to the total sediment yield in various regions, especially in the Mediterranean Region. This is particularly the case of the Guadalquivir River Basin, where the lithology added to the topography and the climate condition make of it a gully prone area. At present, very little information is available on gully processes and dynamics in this area. In this thesis, a complex gully network with a contributing area of 20 km2 was selected as a representative case of the gully prone agricultural landscape of the Campiña of the Guadalquivir River Basin, which land use consists mainly of herbaceous crops and live groves on Vertisols developed over soft parent material (marls and calcareous sandstone). The dynamics of the gully network was study over a period of 57 years by a combination of photointerpretation techniques in a GIS, field surveys and probabilistic approaches. Gully network evolution was derived from a dataset of 10 aerial orthophotos from the period 1956 to 2013. Field data and a Monte Carlo approach were then applied to estimate gully erosion rates dynamics over the study period. Modelling of gully erosion was then assessed by means of the study of the topographic thresholds for gully head initiation and by means of the gully widening rates dynamics. The results showed that gully erosion rate in the study area was 39 ton/ha/year on average, with peaks up to 591 ton/ha/year. However, these gully erosion rates were highly variable over the study period, and therefore the estimation through average values should be taking with caution. The variability on the gully erosion rates obtained highlights the importance of appropriately selecting the time scale on which gully erosion processes are assessed. For the first time, an important temporal variability in the topographic thresholds (TT) values for a given study area was demonstrated. In addition, this TT variability could be correlated to rainfall regime through various rainfall indexes, as for instance the Rainy Day Normal (RDN). A significant correlation between the gully widening rates and the runoff contributing area were found. Variability in gully widening rates were related to a rainfall index expressing the number of days exceeding a threshold rainfall depth of 13 mm. Land use present in the study area (herbaceous crops and olive groves) showed no significant effects on the TT and the widening rates. La erosión por cárcavas es un proceso de degradación del suelo que afecta gravemente a muchas regiones. Estos procesos causan importantes impactos tanto in-situ como ex-situ. A diferencia de lo que ocurre con otros procesos de erosión, como son la erosión laminar y la erosión por regueros, para la erosión por cárcavas no hay desarrollados en la actualidad modelos ampliamente aceptados. Sin embargo, distintos autores han demostrado que la contribución de las cárcavas a la producción total de sedimentos puede superar con creces la del resto de procesos en determinadas regiones, como ocurre por ejemplo en la cuenca del Mediterráneo. En esta tesis se ha analizado una cuenca de la Campiña representativa de las zonas más afectadas por la erosión por cárcavas en la Cuenca del Río Guadalquivir. Mediante técnicas de fotointerpretación de imágenes aéreas, se analizó la dinámica de la red de cárcavas en un periodo de 57 años. Para ello se utilizó una secuencia de 10 ortofotos del periodo comprendido entre 1956 y 2013, con el apoyo de datos de campo. Por último, se avanzó en la modelización de las cabeceras de las cárcavas y del ensanchamiento de las mismas a través de relaciones con el área de contribución, y con índices de precipitación. Los resultados obtenidos mostraron que las tasas de erosión durante el periodo de estudio fueron muy variables, siendo de 39 t ha-1 año-1 el valor medio para el conjunto del periodo y 591 t ha-1 año-1 el máximo obtenido. Por otro lado, se demostró que los umbrales topográficos para la formación de cabeceras pueden variar notablemente a lo largo del tiempo en un mismo área. Por último, se determinó que existe una correlación significativa entre la tasa de ensanchamiento de las cárcavas y el área de contribución aguas arriba. Tanto los umbrales topográficos como las tasas de ensanchamiento pudieron correlacionarse con índices de precipitación. Mientras que, los distintos usos del suelo presentes en la zona de estudio, resultaron poco relevantes para la modelización de los crecimientos en cabecera y en anchura.

Soil is one of the most important natural systems that support the development of life and is part of fundamental processes that make our planetary ecosystem work. It is well known that the factors that intervene in the formation of the soil are climate, bedrock, relief, biota and time. However, despite the numerous studies related to soil formation, little is known about these processes due to the immense complexity in which they are integrated. This study identifies and investigates in detail the different soil-forming processes in the study area located in a rocky Mediterranean landscape. Specifically, the processes that have been studied have been biological such as bioturbation, physical such as erosiondeposit and physical weathering. These processes are related to the spatial distribution of carbon stored in the soil, which has also been part of this study. The spatial distribution of carbon stocks in the soil is highly variable in the study area, as well as bulk density and stoniness. The variable that controls the spatial distribution of the stoniness is the slope, demonstrating the influence of the erosion. The spatial distribution of the carbon content and carbon stocks in the soil depend on vegetation cover and insolation. Bioturbation has been studied in soil profiles at different depths along a steeply inclined slope using the IRSL (Infrared Stimulated Luminescence) luminescence technique used on sand sized feldspar grains for the first time for this purpose. This technique has made it possible to identify the age of the sample at different depths and an effective soil mixing rate that takes into account only those grains that have ever been exposed to the soil surface. This has allowed, for the first time, to identify the border between the mobile regolith and the saprolite because the grains close to the border have never visited the surface.The soil age at different depths previously calculated has been used to determine the bioturbation, erosion and deposition rates along the slope through a new analytical solution of the advection-diffusion equation. Physical weathering has been assessed in the horizons of ten soil profiles by comparing rock fragmentation field data with different models. In this way, the patterns governing rock fragmentation were established in six profiles. The rest of the profiles did not fit any of these models because they are characterized by armouring effect on the surface, i.e. the surface horizon contains larger size of rocks than the lower one due to the removal of fine particles produced by erosion. The study presented here is a great advance in the knowledge of these soil-forming processes and can be implemented in other studies of the same type. In the future, this study could be compared with the results that would be obtained from erosion rates using other methods (10Be or 137Cs), completed with an estimation of the chemical processes in the study area and, finally, useful for the calibration and validation of both the new soil formation model that will be developed linked to the work developed in this thesis, as explained in chapter six, and other soil formation and landscape evolution models to better understand the connection between pedology and geomorphological processes. El suelo es uno de los sistemas naturales más importantes que sustentan el desarrollo de la vida y forma parte de procesos fundamentales que hacen funcionar nuestro ecosistema planetario. Es bien sabido que los factores que intervienen en la formación del suelo son el clima, la roca madre, relieve, biota y el tiempo. Sin embargo, a pesar de los numerosos estudios relacionados con la formación del suelo, poco es conocido sobre estos procesos debido a la inmensa complejidad en la que se integran. Este estudio identifica y profundiza en el conocimiento de varios procesos formadores del suelo en la zona de estudio situada en un ambiente Mediterráneo. Específicamente, los procesos que se han estudiado han sido biológicos como la bioturbación, físicos como la erosión-depósito y la meteorización física. Estos procesos están relacionados con la distribución espacial de carbono almacenado en el suelo, la cual también ha formado parte de este estudio. La distribución espacial del carbono almacenado en el suelo ha resultado ser muy variable en la zona de estudio, caracterizada por ser rocosa, al igual que la densidad aparente y la pedregosidad. Las variables que controlan la distribución espacial de la pedregosidad es la pendiente, demostrándose la influencia de la misma en la erosión. La distribución espacial del contenido de carbono y carbono almacenado en el suelo dependen de la cobertura vegetativa y de la insolación. La bioturbación se ha estudiado en perfiles de suelo a distintas profundidades a lo largo de una ladera con pronunciada pendiente, a través de la técnica de luminiscencia IRSL (Infrared Stimulated Luminescence) usada en granos de feldespato tamaño arena por primera vez para dicho fin. Esta técnica ha permitido identificar la edad de la muestra a diferentes profundidades y una tasa efectiva de mezcla del suelo que tiene en cuenta sólo los granos que alguna vez vieron la luz en la superficie del suelo. Esto ha hecho posible que, por primera vez, se haya identificado el borde entre el regolito móvil y el saprolito debido a que los granos cercanos a esta franja nunca han visitado la superficie. La edad del suelo a diferentes profundidades anteriormente calculada ha sido usada para determinar las tasas de bioturbación, erosión y depósito a lo largo de la ladera a través de una nueva solución analítica de la ecuación advección-difusión. La meteorización física ha sido evaluada en los horizontes de diez perfiles de suelo comparando los datos de campo de fragmentación de rocas con diferentes modelos. De esta forma, se establecieron los patrones que rigen la fragmentación de partículas en seis perfiles. El resto de los perfiles no se ajustaron a ninguno de estos modelos por estar caracterizados por el efecto armouring en la superficie, es decir, el horizonte superficial contiene un tamaño de rocas mayor que el inferior debido a la eliminación de las partículas finas producida por la erosión. El estudio presentado aquí es un gran avance para el conocimiento de estos procesos formadores del suelo y puede ser implementado en otros estudios de la misma índole. En el futuro, este estudio podrá ser comparado con los resultados que se obtendrían de tasas de erosión usando otros métodos (10Be or 137Cs), ser completado con una estimación de los procesos químicos en el área de estudio y, por último, podría ayudar a la calibración y validación tanto del nuevo modelo de formación de suelo que se pretende desarrollar vinculado al trabajo desarrollado en esta tesis, tal y como se explica en el capítulo seis, como de otros modelos de formación de suelo y evolución de paisaje para entender mejor la conexión entre la pedología y los procesos geomorfológicos.