Estimación hidrológica del riesgo de sequía

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

Impact of Climate Change on Agricultural Droughts in Spain

Drought is an important natural hazard that is expected to increase in frequency and intensity as a consequence of climate change. This study aimed to evaluate the impact of future changes in the temperature and precipitation regime of Spain on agricultural droughts, using novel static and dynamic drought indices. Statistically downscaled climate change scenarios from the model HadGEM2-CC, under the scenario representative concentration pathway 8.5 (RCP8.5), were used at a total of 374 sites for the period 2006 to 2100. The evolution of static and dynamic drought stress indices over time show clearly how drought frequency, duration and intensity increase over time. Values of static and dynamic drought indices increase over time, with more frequent occurrences of maximum index values equal to 1, especially towards the end of the century (2071–2100). Spatially, the increase occurs over almost the entire area, except in the more humid northern Spain, and in areas that are already dry at present, which are located in southeast Spain and in the Ebro valley. This study confirms the potential of static and dynamic indices for monitoring and prediction of drought stress

Evaluation of Drought Stress in Cereal through Probabilistic Modelling of Soil Moisture Dynamics

The early and accurate detection of drought episodes is crucial for managing agricultural yield losses and planning adequate policy responses. This study aimed to evaluate the potential of two novel indices, static and dynamic plant water stress, for drought detection and yield prediction. The study was conducted in SW Spain (Córdoba province), covering a 13-year period (2001–2014). The calculation of static and dynamic drought indices was derived from previous ecohydrological work but using a probabilistic simulation of soil moisture content, based on a bucket-type soil water balance, and measured climate data. The results show that both indices satisfactorily detected drought periods occurring in 2005, 2006 and 2012. Both their frequency and length correlated well with annual precipitation, declining exponentially and increasing linearly, respectively. Static and dynamic drought stresses were shown to be highly sensitive to soil depth and annual precipitation, with a complex response, as stress can either increase or decrease as a function of soil depth, depending on the annual precipitation. Finally, the results show that both static and dynamic drought stresses outperform traditional indicators such as the Standardized Precipitation Index (SPI)-3 as predictors of crop yield, and the R2 values are around 0.70, compared to 0.40 for the latter. The results from this study highlight the potential of these new indicators for agricultural drought monitoring and management (e.g., as early warning systems, insurance schemes or water management tools)

Two-dimensional 1H NMR spectra of ferricytochrome c551 from Pseudomonas aeruginosa

AbstractThe full assignment of 1H NMR signals of heme proton resonances of ferricytochrome c551 from Pseudomonas aeruginosa has been performed by means of 2D NMR experiments. This technique allows the complete and unequivocal assignment of all heme resonances, including methylene resonances of the propionic groups, directly implicated in the pH dependence of the redox properties of cytochrome c551

Projected hydrologic changes over the north of the Iberian Peninsula using a Euro-CORDEX multi-model ensemble

This study explores the impacts of climate change on the hydrology of the headwater areas of the Duero River Basin, the largest basin of the Iberian Peninsula. To this end, an ensemble of 18 Euro-CORDEX model experiments was gathered for two periods, 1975–2005 and 2021–2100, under two Representative Concentration Pathways (RCP4.5 and RCP8.5), and were used as the meteorological forcings of the Variable Infiltration Capacity (VIC) during the hydrological modelling exercise. The projected hydrologic changes for the future period were analyzed at annual and seasonal scales using several evaluation metrics, such as the delta changes of the atmospheric and land variables, the runoff and evapotranspiration ratios of the overall water balance, the snowmelt contribution to the total streamflow and the centroid position for the daily hydrograph of the average hydrologic year. Annual streamflow reductions of up to 40% were attained in various parts of the basin for the period 2071–2100 under the RCP8.5 scenario, and resulted from the precipitation decreases in the southern subwatersheds and the combined effect of the precipitation decreases and evapotranspiration increases in the north. The runoff and the evapotranspiration ratios evinced a tendency towards an evaporative regime in the north part of the basin and a strengthening of the evaporative response in the south. Seasonal streamflow changes were mostly negative and dependent on the season considered, with greater detriments in spring and summer, and less intense ones in autumn and winter. The snowmelt contribution to the total streamflow was strongly diminished with decreases reaching −80% in autumn and spring, thus pointing to a change in the snow regime for the Duero mountains. Finally, the annual and seasonal changes of the centroid position accounted for the shape changes of the hydrograph, constituting a measure of seasonality and reflecting high correlations degrees with the streamflow delta changes.Departamento Física Aplicada, Facultad de Ciencias, Universidad de GranadaSpanish Ministry of Economy and625 Competitiveness projects CGL2013-48539-R and CGL2017-89836-REuropean Community Funds (FEDER) and by FEDER/Junta de Andalucía-Consejería627 de Economía y Conocimiento/B-RNM-336-UGR18 projectMinistry of Education, Culture and Sport of Spain (FPU grant FPU17/02098

Evaluation of Glycerylphytate Crosslinked Semi- and Interpenetrated Polymer Membranes of Hyaluronic Acid and Chitosan for Tissue Engineering

In the present study, semi- and interpenetrated polymer network (IPN) systems based on hyaluronic acid (HA) and chitosan using ionic crosslinking of chitosan with a bioactive crosslinker, glycerylphytate (G1Phy), and UV irradiation of methacrylate were developed, characterized and evaluated as potential supports for tissue engineering. Semi- and IPN systems showed significant differences between them regarding composition, morphology, and mechanical properties after physicochemical characterization. Dual crosslinking process of IPN systems enhanced HA retention and mechanical properties, providing also flatter and denser surfaces in comparison to semi-IPN membranes. The biological performance was evaluated on primary human mesenchymal stem cells (hMSCs) and the systems revealed no cytotoxic effect. The excellent biocompatibility of the systems was demonstrated by large spreading areas of hMSCs on hydrogel membrane surfaces. Cell proliferation increased over time for all the systems, being significantly enhanced in the semi-IPN, which suggested that these polymeric membranes could be proposed as an effective promoter system of tissue repair. In this sense, the developed crosslinked biomimetic and biodegradable membranes can provide a stable and amenable environment for hMSCs support and growth with potential applications in the biomedical field.The authors thanks to “La Caixa” Foundation (ID 100010434), which supported Ana Mora-Boza (scholarship code LCF/BQ/ES16/11570018) and to the Spanish Ministry of Economy and Competitiveness for financial support (project RTC-2016-5451-1) and the Fundación Mutua Madrileña (project FMM-AP17196-2019). M. R. Aguilar and B. Vázquez-Lasa are members of the SusPlast platform (Interdisciplinary Platform for Sustainable Plastics towards a Circular Economy) from the Spanish National Research Council (CSIC)

Star formation efficiency and AGN feedback in narrow-line Seyfert 1 galaxies with fast X-ray nuclear winds

We present the first systematic study of the molecular gas and star formation efficiency in a sample of ten narrow-line Seyfert 1 galaxies selected to have X-ray Ultra Fast Outflows and, therefore, to potentially show AGN feedback effects. CO observations were obtained with the IRAM 30m telescope in six galaxies and from the literature for four galaxies. We derived the stellar mass, star formation rate, AGN and FIR dust luminosities by fitting the multi-band spectral energy distributions with the CIGALE code. Most of the galaxies in our sample lie above the main sequence (MS) and the molecular depletion time is one to two orders of magnitude shorter than the one typically measured in local star-forming galaxies. Moreover, we found a promising correlation between the star formation efficiency and the Eddington ratio, as well as a tentative correlation with the AGN luminosity. The role played by the AGN activity in the regulation of star formation within the host galaxies of our sample remains uncertain (little or no effect? positive feedback?). Nevertheless, we can conclude that quenching by the AGN activity is minor and that star formation will likely stop in a short time due to gas exhaustion by the current starburst episode.Comment: Published in MNRAS, Volume 524, Issue 2, Pages 3130-314

Estudio comparativo de distintas bases de datos de humedad del suelo superficial en la Península Ibérica

Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018.[ES]Existen numerosas bases de datos con parámetros que permiten estudiar diversas variables, tanto climáticas como hidrológicas. Una posible aplicación del estudio de estas variables es la validación de datos provenientes de simulaciones, permitiendo establecer la habilidad que proporcionan los modelos de cara a realizar simulaciones de futuro. Esta validación puede ser especialmente complicada en lo referente a humedad del suelo debido a la dificultad que entraña la obtención de datos observacionales. Además, distintas bases de datos expresan la humedad del suelo de forma diferente, por ejemplo, como volumen de agua en un volumen de suelo o como capa de agua equivalente. Por ello, los datos de humedad del suelo no siempre son fácilmente comparables. Así, el objetivo de este trabajo es la comparación de diversas bases de datos de humedad superficial del suelo, provenientes fundamentalmente de datos satelitales y de modelos, para la Península Ibérica (PI). Para ello, se han comparado los patrones de variabilidad espacio-temporal de humedad del suelo aportados por estas bases de datos y se han realizado test estadísticos para determinar si hay correlación entre ellos y conocer las limitaciones de cada conjunto de datos. Se ha comprobado que, en general, todas las bases de datos presentan tendencias similares, si bien los valores absolutos de humedad del suelo son diferentes. En algunos casos, se aprecia que existe una importante correlación entre algunos conjuntos de datos. Esto puede ser debido al uso de modelos de suelo para reescalar y homogeneizar los datos observados.[EN]The existence of several databases containing climate and hydrologic parameters allows the study of their variables. A possible application of the study of these variables is the validation of data obtained from simulations, which makes model skill evaluation possible. This is useful when simulating future scenarios. However, this validation can be especially problematic for soil moisture data due to the difficulty inherent in its acquisition. Moreover, databases use different magnitudes for this variable, e.g. volume of water contained in the soil or thickness of equivalent water layer. Therefore, data cannot be easily compared. The aim of this work is the comparison of several soil moisture databases, mainly from satellite observations and model reanalysis. Spatial and temporal variability of the data was compared, focusing on the Iberian Peninsula. Statistical tests were also performed, in order to determine whether databases are correlated and to know the limitations of the studied datasets. Results of the analysis show that all databases present similar trends, even though their absolute values of soil moisture are different. In some cases, there are strong correlations between the datasets. This may be due to the use of land surface models to re-scale and harmonise observed soil moisture data

Spectral Stacking of Radio-Interferometric Data

Mapping molecular line emission beyond the bright low-J CO transitions is still challenging in extragalactic studies, even with the latest generation of (sub-)mm interferometers, such as ALMA and NOEMA. We summarise and test a spectral stacking method that has been used in the literature to recover low-intensity molecular line emission, such as HCN(1-0), HCO+(1-0), and even fainter lines in external galaxies. The goal is to study the capabilities and limitations of the stacking technique when applied to imaged interferometric observations. The core idea of spectral stacking is to align spectra of the low S/N spectral lines to a known velocity field calculated from a higher S/N line expected to share the kinematics of the fainter line, e.g., CO(1-0) or 21-cm emission. Then these aligned spectra can be coherently averaged to produce potentially high S/N spectral stacks. Here, we use imaged simulated interferometric and total power observations at different signal-to-noise levels, based on real CO observations. For the combined interferometric and total power data, we find that the spectral stacking technique is capable of recovering the integrated intensities even at low S/N levels across most of the region where the high S/N prior is detected. However, when stacking interferometer-only data for low S/N emission, the stacks can miss up to 50% of the emission from the fainter line. A key result of this analysis is that the spectral stacking method is able to recover the true mean line intensities in low S/N cubes and to accurately measure the statistical significance of the recovered lines. To facilitate the application of this technique we provide a public Python package, called PyStacker.Comment: 10 pages, 10 figures, accepted for pub in A&A, Apr 28, 202