Suchergebnisse

Presentación realizada para la conferencia "ICEM 2019", celebrada en Copenhague en junio de 2019. ; A lo largo de esta presentación se explican los resultados obtenidos al aplicar un algoritmo de regresión por cuantiles para calibrar la predicción por conjuntos de radiación directa del ECMWF, y se compara además con predicciones de gSREPS. ; This Project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654984.

33 páginas, 5 figuras, 4 tablas. Proceedings of the NATO Mediterranean Dialogue Workshop on Desertification in the Mediterranean Region. A Security Issue -- Part I. Introducction: Desertification in the Mediterranen Region: Linking environmental condition to security. Valencia, Spain 2-5 December 2003 ; Desertification is a relatively new term but it is also an old issue in the European Mediterranean zone corroborated by the abundance of historical references highlighting the concern of different cultures on important land degradation processes in the region. The perception of this issue has been changing through time with periods of more environmental sensitivity and awareness alternating with periods of less attention and sensibility. In recent decades, a conceptual evolution has occurred, passing from a vaguely defined but real problem to a progressive assimilation and clarification of the physical and socio-economical processes involved, their factors, causes and also the impacts and consequences. In February 1994, the United Nations Convention to Combat Desertification (UNCCD) came into being. The UNCCD dedicates one of its Annexes to the specific problems of affected countries of the Northern Mediterranean region. The regional Annex for the Mediterranean identifies the particular conditions of the region responsible for the threat of desertification processes. Among others, it specifies the semiarid conditions of the countries of this region (Spain has 63.5% of its territory affected by semiarid climatic conditions, Greece has 62%, Portugal 61.5%, Italy has 40% and France 16%), the seasonal droughts, the very high rainfall variability and sudden and high-intensity rainfall. The main factors and causes of desertification processes acting in Europe operate in different temporal and spatial contexts influencing the course of the natural processes involved in desertification. At the global scale, both natural (mainly atmospheric factors) and socio-economic factors (economical, cultural and political) influence the desertification processes. At the European scale, the factors acting are essentially physiographic, meteorological, economic and cultural aspects, and operate over large areas (e.g. river basins, mountain massifs, coastal zones, etc.). At the local scale, the specific physiography, soil types and uses, cultural traditions and land management are relevant factors influencing the desertification processes. A review is presented on the efforts made to evaluate desertification at the global and European scales. The consequences of Desertification also include security issues. The concept of Buzan (1998) on Societal Security should be expanded to include direct and indirect consequences of desertification which affect security aspects such as water scarcity, agricultural-food production, increase in the impacts of flooding, extension of forest fires, annual and interannual drought effects. Also other security aspects affecting Northern Mediterranean countries should be considered such as border security and problems derived from integration and cultural identity of emigrants. ; Peer reviewed

19 páginas, 6 figuras, 2 tablas. Proceedings of the NATO Mediterranean Dialogue Workshop on Desertification in the Mediterranean Region. A Security Issue -- Part IV. Regional cooperation and information sharing. Valencia, Spain 2-5 December 2003 ; Fire is one of the most important determining factors in the evolution of Mediterranean ecosystems. Its effects on soil are plural and diverse, acting on structure, chemical and physical properties, biota etc. Among them, the induced variations on soil water dynamics are of key importance for the recovery of the entire ecosystem and in the soil response to erosion processes. Forest fires are also a factor, triggering the risk of desertification. The aim of this study is to assess the impact effect of different fire intensities on soil hydrology and on runoff generation. This work was developed in the Permanent Experimental Field Station of La Concordia with nine plots (4 x 20 m), installed in a calcareous hillside, representative of Mediterranean shrubland areas. Experimental fires, of two intensity levels were carried out. Three plots were burned reaching high fire intensity and other three plots were burned with moderate intensity and the remaining plots were left undisturbed as control. Soil water content, water retention capacity and pF curves were measured together with runoff generation dynamics, in the different plots. The intrinsic characteristics of each rain event occurred up until a year after the fires and runoff generated on them were monitored. The data obtained was compared with the state of the plots seven years after, during the 2000-2002 period. In this period 24 rain events with runoff generation occurred, with average rainfall intensities (I30) around 10mm h-1. Both fire treatments show significant differences with respect to the Control plots, which are reflected in a value of runoff production of 76.84% as an average, less than the burned plots. Between fire treatments, the plots burned with high intensity fire, show the highest values of runoff yield. However, infiltration rates do not give significant differences between fire treatments. In the same way, plots that suffer a high intensity fire show greater values (22.50 cm3 cm-3) on water retention capacity than the other treatments, giving significant differences with the Moderate intensity plots and Control ones. Differences on this parameter between plots burned with Moderate intensity and the Control ones were observed but they were not statistically significant. The obtained pF curves show the same tendencies, being the greatest water content retained at pF of 2 in the burned plots and in the Control ones at pF of 4.2. The effect of fire degrading the vegetation cover and by means of the temperature impact on soil, produce changes in its structural characteristics and porosity, affecting soil water distribution and the effective response on water erosion processes. ; This work has been supported by the European Union (QLRT-2000-00289), the Spanish Ministry of Science and Technology (CICYT) REN2001-1716, and the Generalitat Valenciana (Conselleria de Medio ambiente-2002X628). ; Peer reviewed

10 páginas, 7 figuras, 7 tablas. ; An experimental study based on the effects of fire on soil hydrology was developed at the Experimental Station of 'La Concordia' (Valencia, Spain). It is located on a calcareous hillside facing SSE and composed of nine erosion plots (4 x 20 m). In summer 2003, after eight years of soil and vegetation recovery from previous fires in 1995 (with three fire treatments: T1 high-intensity fire, T2 moderate intensity, and T3 not burnt), experimental fires of low intensity were again conducted on the plots already burnt, to study the effects of repeated fires on the soil water infiltration, soil water content and runoff. Infiltration rates and capacities were measured by the mini-disk infiltrometer method (MDI), assessing the effects of vegetation cover by comparing the under-canopy microenvironment (UC) and its absence on bare soil (BS), immediately before and after the fire experiments. Soil properties like water retention capacity (SWRC) and water content (SWC) were also determined for the different fire treatments (T1, T2 and T3) and microsites (UC and BS). Hydrological parameters, such as runoff and infiltration rate, were monitored at plot scale from July 2002 to July 2004. In the post-fire period, data displayed a 20% runoff increase and a decrease in infiltration (18%). Differences in the steady-state infiltration rate (SSI) and infiltration capacity (IC) were tested with the MDI on the different treatments (T1, T2 and T3), and between the UC and BS microsites of each treatment. After fire, the SSI of the UC soil declined from 16 mm h(-1) to 12 mm h(-1) on T1, and from 24 mm h(-1) to 19 mm h(-1) on T2. The IC was reduced by 2/3 in the T1 UC soil, and by half on T2 UC soil. On the BS of T1 and T2, the fire effect was minimal, and higher infiltration rates and capacities were reached. Therefore, the presence/absence of vegetation when burnt influenced the post-burnt infiltration patterns at soil microscale. On the T3, different rates and capacities were obtained depending on the microsites (UC and BS), with higher SSI (25 mm h(-1)) and IC (226 mm h(-1)) on BS than on UC (SSI of 18 mm h(-1) and IC of 136 mm h(-1)). The SWRC and SWC were recovered from 1995 to 2003 (prior to the fires). The 2003 fire promoted high variability on the SWC at pF 0.1, 2 and 2.5, and the SWRC on burnt soils were reduced. To summarize, the IC and SSI post-fire decreases were related to the lower infiltration rate at plot scale, the significant differences in the SWRC between burnt and control treatments, and the increase in the runoff yield (20%). According to the results, the MDI was a useful tool to characterize the soil infiltration on the vegetation patches of the Mediterranean maquia, and contrary to other studies, on the UC soil, the infiltration rate and IC, when soil was dry, were lower than that obtained on BS. Once the soil gets wet, similar values were found on both microenvironments. ; We thank the financial support from the Agreement Generalitat Valenciana - CSIC (2005020112) 'Impacto de los incendios forestales repetidos sobre los procesos de erosión hídrica del suelo y la recuperación de la cubierta vegetal. Seguimiento y evaluación en una estación permanente de campo', and the Ministerio de Educación y Ciencia of the Spanish Government project 'Procesos y balances hidrológicos y de sedimentos a diferentes escalas espaciales en ambientes mediterráneos: Efectos de la variabilidad climática y los cambios de uso del suelo' (PROBASE CGL2006-11619). ; Peer reviewed

7 páginas, 4 figuras, 3 tablas. ; Soil macroaggregation in relation to soil organic matter (SOM) and calcium carbonate(CaCO3) content was studied, before and after experimental fires of different intensities, in two environments (under canopy and on bare soil). In 1995, two experimental fire treatments, based on the addition of different biomass amounts, were applied on a set of nine plots at the Permanent Field Station of La Concordia (Valencia, Spain). Three plots were burned with high intensity fire (T1), three with moderate intensity (T2) and three plots were left unburned to be used as control treatment (T3). Soils under canopy were characterized by higher macroaggregate stability (SMS), SOM content and mean weight diameter of aggregates (MWD) than bare soils, which presented higher CaCO3 contents. After the fires, tendencies to increase were observed in the SOM and SMS of all burned soils, probably because of the incorporation of partially burned plant material. The trends of SMS and SOM in T1 burned soils were towards to decrease with the occurrence of the first erosive rainfalls. These trends continued until the end of the study. MWD of under canopy soils on T1 and of soils on T2 showed a decreasing trend immediately after fire treatments. Not significant differences between sampling periods were found for CaCO3 content, with the exception of under canopy soils on T1 which tended to increase, and showed higher values at the end of the studied period. The differences observed initially between under canopy and bare soil disappeared after one year of fire in T1, which suggests a major degradation of soils affected by this treatment. Significant changes of the studied properties were not observed in unburned soils during one year of research. In these soils, organic matter showed significant correlations with macroaggregate stability and mean weight diameter. However, significant statistical relationships were not observed between the Studied properties in burned soils, showing that fire impact probably affected other soil characteristics related to soil aggregation. ; We thank the financial support from the Agreement Generalitat Valenciana — CSIC (2005020112) "Impacto de los incendios forestalesrepetidos sobre los procesos de erosión hídrica del suelo y la recuperación de la cubierta vegetal. Seguimiento y evaluación en una estación permanente de campo", and the Ministerio de Educación y Ciencia of the Spanish Government project "Procesos y balances hidrológicos y de sedimentos a diferentes escalas espaciales en ambientes mediterráneos: Efectos de la variabilidad climática y los cambios de uso del suelo" (PROBASE CGL2006-11619). ; Peer reviewed

12 páginas, 6 figuras, 3 tablas. ; In the Mediterranean area, forest fires have become a first-order environmental problem. Increased fire frequency progressively reduces ecosystem recovery periods. The fire season, usually followed by torrential rains in autumn, intensifies erosion processes and increases desertification risk. In this work, the effect of repeated experimental fires on soil response to water erosion is studied in the Permanent Field Station of La Concordia, Valencia, Spain. In nine 80 m2 plots (20 m long x 4 m wide), all runoff and sediment produced were measured after each rainfall event. In 1995, two fire treatments with the addition of different biomass amounts were applied. Three plots were burned with high fire intensity, three with moderate intensity, and three were unburned to be used as a control. In 2003, the plots with the fire treatments were burned again with low fire intensities. During the eight-year interval between fires, plots remained undisturbed, allowing regeneration of the vegetation–soil system. Results obtained during the first five months after both fire experiments show the high vulnerability of the soil to erosion after a repeated fire. For the burned plots, runoff rates increased three times as much asore than those of 1995, and soil losses increased almost twice. The highest sediment yield (514 g m-2) was measured in 2003, in athe plots of the moderate burned with moderate fire intensity treatment in 1995, which had yielded only 231 g m-2 of sediment during the corresponding period in 1995. Runoff yield from the control plots did not show significant temporal changes, while soil losses decreased from 5 g m-2 in the first post-fire period to 0.7 g m-2 in the second one. ; We thank financial support from the EEC project "Eco-engineering and conservation of slopes for long term protection against landslides, storms and erosion" (QLRT-2000-00289), the Convenio Generalitat Valenciana - CSIC (02020024) and the Ministerio de Ciencia y Tecnología of the Spanish Government project (CYCIT REN2001-1716). ; Peer reviewed

8 páginas, 5 figuras, 3 tablas. ; The influence of vegetation cover on soil hydrological properties and its response to the impact of different fire intensities, in a Mediterranean forest environment, has been evaluated. The study was carried out in the Permanent Experimental Field Station of La Concordia (Lliria-Valencia, Spain), on a set of nine erosion plots (4 x 20 m(2)). The Station is located on a calcareous hillside S-SE oriented, with soils of Rendzic Leptosol type and supporting Mediterranean shrubland vegetation. All runoff generated and sediment produced in every rain event was collected from each plot. The set up includes a system of sensors for the continuous monitoring of climatic parameters (air temperature and humidity, rain volume, intensity, etc.). In June 1995, a set of experimental fires was carried out to the Station. Three of the plots were burned with high intensity fire, three with moderate intensity and the remaining were left unaltered. Soil water content and water retention capacity (WRC) were measured in the different plots and in two different vegetation covers: under canopy (UC) and in bare soil (BS). The pF curves were also obtained for each fire treatment. A year after the fires (June 1995-June 1996), great differences, reaching 77.15%, in runoff generation between fire treatments and the control plots were observed. No significant differences were detected on water retention capacity between soils UC and BS in the burned plots. However, these differences appeared in the control plots, giving UC and BS values of 13% and 18%, respectively. Plots corresponding to the high intensity fire treatment showed values of WRC significantly higher than those of the moderate intensity and of the control treatments. The pF curves show that the values of water volume, at the different pressure points studied, were slightly greater on UC soil. Values obtained for BS samples are higher in the fire treatments, showing significant differences in respect to the control plots at pF 1 and 2. These differences were also observed for UC soil, but in this case at pF 2, 2.5 and 4.2. ; This work has been supported by the European Union (QLRT-2000-00289), the Spanish Ministry of Science and Technology (CICYT) REN2001-1716 and Convenio (Agreement) Generalitat Valenciana – CSIC (02020024). ; Peer reviewed

There is a general consensus that healthy soils are pivotal for food security. Food production is one of the main ecosystem services provided by and thus dependent on well-functioning soils. There are also intrinsic connections between the four pillars of food security: food availability, access, utilization, and stability; with how soils are managed, accessed and secured, in particular by food insecure and vulnerable populations. On the other hand, socio-political and economic processes that precipitate inequalities and heighten vulnerabilities among poor populations often increase pressure on soils due to unsustainable forms of land use and poor agricultural practises. This has often led to scenarios that can be described as: 'poor soils, empty stomachs (hungry people) and poor livelihoods.' In 2015, in particular, as we head towards approval of the 'Sustainable Development Goals' (SDGs), the role of Financing for Development is debated and agreed upon and a new climate pact is signed – these three political dimensions define how a new post-2015 agenda needs to be people-smart as well as resource-smart. For proposed SDG 2 (Food Security and Hunger), there can be so resolution without addressing people, policies and institutions.

A detailed knowledge of the solar resource is a critical point in the design and control of Concentrating Solar Power (CSP) plants. In particular, accurate forecasting of solar irradiance is essential for the efficient operation of solar thermal power plants, the management of energy markets, and the widespread implementation of this technology. Numerical weather prediction (NWP) models are commonly used for solar radiation forecasting. In the ECMWF deterministic forecasting system, all forecast parameters are commercially available worldwide at 3-hourly intervals. Unfortunately, as Direct Normal solar Irradiance (DNI) exhibits a great variability due to the dynamic effects of passing clouds, 3-h time resolution is insufficient for accurate simulations of CSP plants due to their nonlinear response to DNI, governed by various thermal inertias due to their complex response characteristics. DNI series of hourly or sub-hourly frequency resolution are normally used for an accurate modeling and analysis of transient processes in CSP technologies. In this context, the objective of this study is to propose a methodology for generating synthetic DNI time series at 1-h (or higher) temporal resolution from 3-h DNI series. The methodology is based upon patterns as being defined with help of the clear-sky envelope approach together with a forecast of maximum DNI value, and it has been validated with high quality measured DNI data. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654984.

Póster elaborado para la conferencia "SolarPaces 2016" celebrada los días 11-14 de octubre de 2016 en Abu Dhabi. ; This Project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654984.