Extreme temperature events analyzed with Fast Fourier Transform

Extreme weather and climate events have received increased attention in the last few years, due to the often large loss of agriculture business and exponentially increasing costs associated with them and insurance planning. This increased attention raises the question as to whether extreme weather and climate events are truly increasing, whether this is only a perceived increase exacerbated by enhanced media coverage, or both. There are a number of ways extreme climate events can be defined, such as extreme daily temperatures, extreme daily rainfall amounts, and large areas experiencing unusually warm monthly temperatures, among others. In this study, we will focus our attention in frost and heatstroke events measuring it as the number of days under 0 ºC and number of days with daily maximum over 30ºC monthly respectively. We have studied the trends in these extreme events applying a Fast Fourier Transform to the series to clarify the tendency. Lack of long-term climate data suitable for analysis of extremes is the single biggest obstacle to quantifying whether extreme events have changed over the twentieth century, including high temporal and spatial resolution observations of temperatures. However, several series have been grouped in different ways: chosen the longest series independently, by provinces, by main watersheds and altitude. On the other hand, synthetic series generated by Luna and Balairón (AEMet) were also analyzed. The results obtained by different pooling data are discussed concluding the difficulties to assess the extreme events tendencies and high regional variation in the trends.

Frequency and Intensity of drought events over Ebro River basin.

Lately, several researchers have pointed out that climate change is expected to increase temperatures and lower rainfall in Mediterranean regions, simultaneously increasing the intensity of extreme rainfall events. These changes could have consequences regarding rainfall regime, erosion, sediment transport and water quality, soil management, and new designs in diversion ditches. Climate change is expected to result in increasingly unpredictable and variable rainfall, in amount and timing, changing seasonal patterns and increasing the frequency of extreme weather events. Consequently, the evolution of frequency and intensity of drought periods is of most important as in agro-ecosystems many processes will be affected by them. Realising the complex and important consequences of an increasing frequency of extreme droughts at the Ebro River basin, our aim is to study the evolution of drought events at this site statistically, with emphasis on the occurrence and intensity of them. For this purpose, fourteen meteorological stations were selected based on the length of the rainfall series and the climatic classification to obtain a representative untreated dataset from the river basin. Daily rainfall series from 1957 to 2002 were obtained from each meteorological station and no-rain period frequency as the consecutive numbers of days were extracted. Based on this data, we study changes in the probability distribution in several sub-periods. Moreover we used the Standardized Precipitation Index (SPI) for identification of drought events in a year scale and then we use this index to fit log-linear models to the contingency tables between the SPI index and the sub-periods, this adjusted is carried out with the help of ANOVA inference.

Evolution of extreme temperature events in short term climate projection for Iberian Peninsula

Extreme events of maximum and minimum temperatures are a main hazard for agricultural production in Iberian Peninsula. For this purpose, in this study we analyze projections of their evolution that could be valid for the next decade, represented in this study by the 30-year period 2004-2034 (target period). For this purpose two kinds of data were used in this study: 1) observations from the station network of AEMET (Spanish National Meteorological Agency) for five Spanish locations, and 2) simulated data at a resolution of 50 50 km horizontal grid derived from the outputs of twelve Regional Climate Models (RCMs) taken from project ENSEMBLES (van der Linden and Mitchell, 2009), with a bias correction (Dosio and Paruolo, 2011; Dosio et al., 2012) regarding the observational dataset Spain02 (Herrera et al., 2012). To validate the simulated climate, the available period of observations was compared to a baseline period (1964-1994) of simulated climate for all locations. Then, to analyze the changes for the present/very next future, probability of extreme temperature events for 2004-2034 were compared to that of the baseline period. Although only minor changes are expected, small variations in variability may have a significant impact in crop performance.

Extreme overirradiance events in Sao Paulo, Brazil

Phenomena of overirradiance have been pointed all over the World. This note presents the most extreme enhancement event reported in Brazil, which contains an irradiance reading of 1590 W/m2 measured in São Paulo (latitude 23°32′S) at relatively low altitude (760 m a.s.l.).

El análogo natural de almacenamiento y escape de Co2 de la cuenca de Gañuelas-Mazarrón : implicaciones para el comportamiento y la seguridad de un almacenamiento de Co2 en estaso supercrítico

El aumento de la temperatura media de la Tierra durante el pasado siglo en casi 1 ºC; la subida del nivel medio del mar; la disminución del volumen de hielo y nieve terrestres; la fuerte variabilidad del clima y los episodios climáticos extremos que se vienen sucediendo durante las ultimas décadas; y el aumento de las epidemias y enfermedades infecciosas son solo algunas de las evidencias del cambio climático actual, causado, principalmente, por la acumulación de gases de efecto invernadero en la atmósfera por actividades antropogénicas. La problemática y preocupación creciente surgida a raíz de estos fenómenos, motivo que, en 1997, se adoptara el denominado “Protocolo de Kyoto” (Japón), por el que los países firmantes adoptaron diferentes medidas destinadas a controlar y reducir las emisiones de los citados gases. Entre estas medidas cabe destacar las tecnologías CAC, enfocadas a la captura, transporte y almacenamiento de CO2. En este contexto se aprobó, en octubre de 2008, el Proyecto Singular Estratégico “Tecnologías avanzadas de generación, captura y almacenamiento de CO2” (PSE-120000-2008-6), cofinanciado por el Ministerio de Ciencia e Innovación y el FEDER, el cual abordaba, en su Subproyecto “Almacenamiento Geológico de CO2” (PSS-120000-2008-31), el estudio detallado, entre otros, del Análogo Natural de Almacenamiento y Escape de CO2 de la cuenca de Ganuelas-Mazarrón (Murcia). Es precisamente en el marco de dicho Proyecto en el que se ha realizado este trabajo, cuyo objetivo final ha sido el de predecir el comportamiento y evaluar la seguridad, a corto, medio y largo plazo, de un Almacenamiento Geológico Profundo de CO2 (AGP-CO2), mediante el estudio integral del citado análogo natural. Este estudio ha comprendido: i) la contextualización geológica e hidrogeológica de la cuenca, así como la investigación geofísica de la misma; ii) la toma de muestras de aguas de algunos acuíferos seleccionados con el fin de realizar su estudio hidrogeoquímico e isotópico; iii) la caracterización mineralógica, petrográfica, geoquímica e isotópica de los travertinos precipitados a partir de las aguas de algunos de los sondeos de la cuenca; y iv) la medida y caracterización química e isotópica de los gases libres y disueltos detectados en la cuenca, con especial atención al CO2 y 222Rn. Esta información, desarrollada en capítulos independientes, ha permitido realizar un modelo conceptual de funcionamiento del sistema natural que constituye la cuenca de Ganuelas-Mazarrón, así como establecer las analogías entre este y un AGP-CO2, con posibles escapes naturales y/o antropogénicos. La aplicación de toda esta información ha servido, por un lado, para predecir el comportamiento y evaluar la seguridad, a corto, medio y largo plazo, de un AGP-CO2 y, por otro, proponer una metodología general aplicable al estudio de posibles emplazamientos de AGP-CO2 desde la perspectiva de los reservorios naturales de CO2. Los resultados más importantes indican que la cuenca de Ganuelas-Mazarrón se trata de una cubeta o fosa tectónica delimitada por fallas normales, con importantes saltos verticales, que hunden al substrato rocoso (Complejo Nevado-Filabride), y rellenas, generalmente, por materiales volcánicos-subvolcánicos ácidos. Además, esta cuenca se encuentra rellena por formaciones menos resistivas que son, de muro a techo, las margas miocenas, predominantes y casi exclusivas de la cuenca, y los conglomerados y gravas pliocuaternarias. El acuífero salino profundo y enriquecido en CO2, puesto de manifiesto por la xx exploración geotérmica realizada en dicha cuenca durante la década de los 80 y objeto principal de este estudio, se encuentra a techo de los materiales del Complejo Nevado-Filabride, a una profundidad que podría superar los 800 m, según los datos de la investigación mediante sondeos y geofísica. Por ello, no se descarta la posibilidad de que el CO2 se encuentre en estado supe critico, por lo que la citada cuenca reuniría las características principales de un almacenamiento geológico natural y profundo de CO2, o análogo natural de un AGP-CO2 en un acuífero salino profundo. La sobreexplotación de los acuíferos mas someros de la cuenca, con fines agrícolas, origino, por el descenso de sus niveles piezométricos y de la presión hidrostática, el ascenso de las aguas profundas, salinas y enriquecidas en CO2, las cuales son las responsables de la contaminación de dichos acuíferos. El estudio hidrogeoquímico de las aguas de los acuíferos investigados muestra una gran variedad de hidrofacies, incluso en aquellos de litología similar. La alta salinidad de estas aguas las hace inservibles tanto para el consumo humano como para fines agrícolas. Además, el carácter ligeramente ácido de la mayoría de estas aguas determina que tengan gran capacidad para disolver y transportar, hacia la superficie, elementos pesados y/o tóxicos, entre los que destaca el U, elemento abundante en las rocas volcánicas ácidas de la cuenca, con contenidos de hasta 14 ppm, y en forma de uraninita submicroscópica. El estudio isotópico ha permitido discernir el origen, entre otros, del C del DIC de las aguas (δ13C-DIC), explicándose como una mezcla de dos componentes principales: uno, procedente de la descomposición térmica de las calizas y mármoles del substrato y, otro, de origen edáfico, sin descartar una aportación menor de C de origen mantélico. El estudio de los travertinos que se están formando a la salida de las aguas de algunos sondeos, por la desgasificación rápida de CO2 y el consiguiente aumento de pH, ha permitido destacar este fenómeno, por analogía, como alerta de escapes de CO2 desde un AGP-CO2. El análisis de los gases disueltos y libres, con especial atención al CO2 y al 222Rn asociado, indican que el C del CO2, tanto disuelto como en fase libre, tiene un origen similar al del DIC, confirmándose la menor contribución de CO2 de origen mantélico, dada la relación R/Ra del He existente en estos gases. El 222Rn sería el generado por el decaimiento radiactivo del U, particularmente abundante en las rocas volcánicas de la cuenca, y/o por el 226Ra procedente del U o del existente en los yesos mesinienses de la cuenca. Además, el CO2 actúa como carrier del 222Rn, hecho evidenciado en las anomalías positivas de ambos gases a ~ 1 m de profundidad y relacionadas principalmente con perturbaciones naturales (fallas y contactos) y antropogénicas (sondeos). La signatura isotópica del C a partir del DIC, de los carbonatos (travertinos), y del CO2 disuelto y libre, sugiere que esta señal puede usarse como un excelente trazador de los escapes de CO2 desde un AGPCO2, en el cual se inyectara un CO2 procedente, generalmente, de la combustión de combustibles fósiles, con un δ13C(V-PDB) de ~ -30 ‰. Estos resultados han permitido construir un modelo conceptual de funcionamiento del sistema natural de la cuenca de Ganuelas-Mazarrón como análogo natural de un AGP-CO2, y establecer las relaciones entre ambos. Así, las analogías mas importantes, en cuanto a los elementos del sistema, serian la existencia de: i) un acuífero salino profundo enriquecido en CO2, que seria análoga a la formación almacén de un AGPxxi CO2; ii) una formación sedimentaria margosa que, con una potencia superior a 500 m, se correspondería con la formación sello de un AGP-CO2; y iii) acuíferos mas someros con aguas dulces y aptas para el consumo humano, rocas volcánicas ricas en U y fallas que se encuentran selladas por yesos y/o margas; elementos que también podrían concurrir en un emplazamiento de un AGP-CO2. Por otro lado, los procesos análogos mas importantes identificados serian: i) la inyección ascendente del CO2, que seria análoga a la inyección de CO2 de origen antropogénico, pero este con una signatura isotópica δ13C(V-PDB) de ~ -30 ‰; ii) la disolución de CO2 y 222Rn en las aguas del acuífero profundo, lo que seria análogo a la disolución de dichos gases en la formación almacén de un AGP-CO2; iii) la contaminación de los acuíferos mas someros por el ascenso de las aguas sobresaturadas en CO2, proceso que seria análogo a la contaminación que se produciría en los acuíferos existentes por encima de un AGP-CO2, siempre que este se perturbara natural (reactivación de fallas) o artificialmente (sondeos); iv) la desgasificación (CO2 y gases asociados, entre los que destaca el 222Rn) del acuífero salino profundo a través de sondeos, proceso análogo al que pudiera ocurrir en un AGP-CO2 perturbado; y v) la formación rápida de travertinos, proceso análogo indicativo de que el AGP-CO2 ha perdido su estanqueidad. La identificación de las analogías más importantes ha permitido, además, analizar y evaluar, de manera aproximada, el comportamiento y la seguridad, a corto, medio y largo plazo, de un AGP-CO2 emplazado en un contexto geológico similar al sistema natural estudiado. Para ello se ha seguido la metodología basada en el análisis e identificación de los FEPs (Features, Events and Processes), los cuales se han combinado entre sí para generar y analizar diferentes escenarios de evolución del sistema (scenario analysis). Estos escenarios de evolución identificados en el sistema natural perturbado, relacionados con la perforación de sondeos, sobreexplotación de acuíferos, precipitación rápida de travertinos, etc., serian análogos a los que podrían ocurrir en un AGP-CO2 que también fuera perturbado antropogénicamente, por lo que resulta totalmente necesario evitar la perturbación artificial de la formación sello del AGPCO2. Por último, con toda la información obtenida se ha propuesto una metodología de estudio que pueda aplicarse al estudio de posibles emplazamientos de un AGP-CO2 desde la perspectiva de los reservorios naturales de CO2, sean estancos o no. Esta metodología comprende varias fases de estudio, que comprendería la caracterización geológico-estructural del sitio y de sus componentes (agua, roca y gases), la identificación de las analogías entre un sistema natural de almacenamiento de CO2 y un modelo conceptual de un AGP-CO2, y el establecimiento de las implicaciones para el comportamiento y la seguridad de un AGP-CO2. ABSTRACT The accumulation of the anthropogenic greenhouse gases in the atmosphere is the main responsible for: i) the increase in the average temperature of the Earth over the past century by almost 1 °C; ii) the rise in the mean sea level; iii) the drop of the ice volume and terrestrial snow; iv) the strong climate variability and extreme weather events that have been happening over the last decades; and v) the spread of epidemics and infectious diseases. All of these events are just some of the evidence of current climate change. The problems and growing concern related to these phenomena, prompted the adoption of the so-called "Kyoto Protocol" (Japan) in 1997, in which the signatory countries established different measurements to control and reduce the emissions of the greenhouse gases. These measurements include the CCS technologies, focused on the capture, transport and storage of CO2. Within this context, it was approved, in October 2008, the Strategic Singular Project "Tecnologías avanzadas de generación, captura y almacenamiento de CO2" (PSE-120000-2008-6), supported by the Ministry of Science and Innovation and the FEDER funds. This Project, by means of the Subproject "Geological Storage of CO2" (PSS- 120000-2008-31), was focused on the detailed study of the Natural Analogue of CO2 Storage and Leakage located in the Ganuelas-Mazarron Tertiary basin (Murcia), among other Spanish Natural Analogues. This research work has been performed in the framework of this Subproject, being its final objective to predict the behaviour and evaluate the safety, at short, medium and long-term, of a CO2 Deep Geological Storage (CO2-DGS) by means of a comprehensive study of the abovementioned Natural Analogue. This study comprises: i) the geological and hydrogeological context of the basin and its geophysical research; ii) the water sampling of the selected aquifers to establish their hydrogeochemical and isotopic features; iii) the mineralogical, petrographic, geochemical and isotopic characterisation of the travertines formed from upwelling groundwater of several hydrogeological and geothermal wells; and iv) the measurement of the free and dissolved gases detected in the basin, as well as their chemical and isotopic characterisation, mainly regarding CO2 and 222Rn. This information, summarised in separate chapters in the text, has enabled to build a conceptual model of the studied natural system and to establish the analogies between both the studied natural system and a CO2-DGS, with possible natural and/or anthropogenic escapes. All this information has served, firstly, to predict the behaviour and to evaluate the safety, at short, medium and long-term, of a CO2-DGS and, secondly, to propose a general methodology to study suitable sites for a CO2-DGS, taking into account the lessons learned from this CO2 natural reservoir. The main results indicate that the Ganuelas-Mazarron basin is a graben bounded by normal faults with significant vertical movements, which move down the metamorphic substrate (Nevado-Filabride Complex), and filled with acid volcanic-subvolcanic rocks. Furthermore, this basin is filled with two sedimentary formations: i) the Miocene marls, which are predominant and almost exclusive in the basin; xxiv and ii) the Plio-Quaternary conglomerates and gravels. A deep saline CO2-rich aquifer was evidenced in this basin as a result of the geothermal exploration wells performed during the 80s, located just at the top of the Nevado-Filabride Complex and at a depth that could exceed 800 m, according to the geophysical exploration performed. This saline CO2-rich aquifer is precisely the main object of this study. Therefore, it is not discarded the possibility that the CO2 in this aquifer be in supercritical state. Consequently, the aforementioned basin gathers the main characteristics of a natural and deep CO2 geological storage, or natural analogue of a CO2-DGS in a deep saline aquifer. The overexploitation of the shallow aquifers in this basin for agriculture purposes caused the drop of the groundwater levels and hydrostatic pressures, and, as a result, the ascent of the deep saline and CO2-rich groundwater, which is the responsible for the contamination of the shallow and fresh aquifers. The hydrogeochemical features of groundwater from the investigated aquifers show the presence of very different hydrofacies, even in those with similar lithology. The high salinity of this groundwater prevents the human and agricultural uses. In addition, the slightly acidic character of most of these waters determines their capacity to dissolve and transport towards the surface heavy and/or toxic elements, among which U is highlighted. This element is abundant in the acidic volcanic rocks of the basin, with concentrations up to 14 ppm, mainly as sub-microscopic uraninite crystals. The isotopic study of this groundwater, particularly the isotopic signature of C from DIC (δ13C-DIC), suggests that dissolved C can be explained considering a mixture of C from two main different sources: i) from the thermal decomposition of limestones and marbles forming the substrate; and ii) from edaphic origin. However, a minor contribution of C from mantle degassing cannot be discarded. The study of travertines being formed from upwelling groundwater of several hydrogeological and geothermal wells, as a result of the fast CO2 degassing and the pH increase, has allowed highlighting this phenomenon, by analogy, as an alert for the CO2 leakages from a CO2-DGS. The analysis of the dissolved and free gases, with special attention to CO2 and 222Rn, indicates that the C from the dissolved and free CO2 has a similar origin to that of the DIC. The R/Ra ratio of He corroborates the minor contribution of CO2 from the mantle degassing. Furthermore, 222Rn is generated by the radioactive decay of U, particularly abundant in the volcanic rocks of the basin, and/or by 226Ra from the U or from the Messinian gypsum in the basin. Moreover, CO2 acts as a carrier of the 222Rn, a fact evidenced by the positive anomalies of both gases at ~ 1 m depth and mainly related to natural (faults and contacts) and anthropogenic (wells) perturbations. The isotopic signature of C from DIC, carbonates (travertines), and dissolved and free CO2, suggests that this parameter can be used as an excellent tracer of CO2 escapes from a CO2-DGS, in which CO2 usually from the combustion of fossil fuels, with δ13C(V-PDB) of ~ -30 ‰, will be injected. All of these results have allowed to build a conceptual model of the behaviour of the natural system studied as a natural analogue of a CO2-DGS, as well as to establish the relationships between both natural xxv and artificial systems. Thus, the most important analogies, regarding the elements of the system, would be the presence of: i) a deep saline CO2-rich aquifer, which would be analogous to the storage formation of a CO2-DGS; ii) a marly sedimentary formation with a thickness greater than 500 m, which would correspond to the sealing formation of a CO2-DGS; and iii) shallow aquifers with fresh waters suitable for human consumption, U-rich volcanic rocks, and faults that are sealed by gypsums and/or marls; geological elements that could also be present in a CO2-DGS. On the other hand, the most important analogous processes identified are: i) the upward injection of CO2, which would be analogous to the downward injection of the anthropogenic CO2, this last with a δ13C(V-PDB) of ~ -30 ‰; ii) the dissolution of CO2 and 222Rn in groundwater of the deep aquifer, which would be analogous to the dissolution of these gases in the storage formation of a CO2-DGS; iii) the contamination of the shallow aquifers by the uprising of CO2-oversaturated groundwater, an analogous process to the contamination that would occur in shallow aquifers located above a CO2-DGS, whenever it was naturally (reactivation of faults) or artificially (wells) perturbed; iv) the degassing (CO2 and associated gases, among which 222Rn is remarkable) of the deep saline aquifer through wells, process which could be similar in a perturbed CO2- DGS; v) the rapid formation of travertines, indicating that the CO2-DGS has lost its seal capacity. The identification of the most important analogies has also allowed analysing and evaluating, approximately, the behaviour and safety in the short, medium and long term, of a CO2-DGS hosted in a similar geological context of the natural system studied. For that, it has been followed the methodology based on the analysis and identification of FEPs (Features, Events and Processes) that have been combined together in order to generate and analyse different scenarios of the system evolution (scenario analysis). These identified scenarios in the perturbed natural system, related to boreholes, overexploitation of aquifers, rapid precipitation of travertines, etc., would be similar to those that might occur in a CO2-DGS anthropogenically perturbed, so that it is absolutely necessary to avoid the artificial perturbation of the seal formation of a CO2-DGS. Finally, a useful methodology for the study of possible sites for a CO2-DGS is suggested based on the information obtained from this investigation, taking into account the lessons learned from this CO2 natural reservoir. This methodology comprises several phases of study, including the geological and structural characterisation of the site and its components (water, rock and gases), the identification of the analogies between a CO2 storage natural system and a conceptual model of a CO2-DGS, and the implications regarding the behaviour and safety of a CO2-DGS.

The Economic Impacts Of Climate Change On The Chilean Agricultural Sector

The agricultural sector could be one of the most vulnerable economic sectors to the impacts of climate change in the coming decades. Climate change impacts are related to changes in the growth period, extreme weather events, and changes in temperature and recipitation patterns, among others. All of these impacts may have significant consequences on agricultural production(Bates, et al.2008. A main issue regarding climate change impacts is related to the uncertainty associated with their occurrence. Climate change impacts can bestimated with simulation models based on several assumptions, among which the future patterns of emissions of greenhouse g asses are quite likely the most relevant, driving the development of future scenarios, i.e. plausible visions of how the future may unfold. Those scenarios are developed as storylines associated with different assumptions about climate and socioeconomic conditions and emissions, with reference figures, such as demographic projections, average global temperatures, etc.(Intergovernmental Panel on Climate Change 2000). Within this context, climate change impact assessment is forced to consider multiple and interconnected sources of uncertainty in order to produce valuable information for policymakers.

Continuous multi-criteria methods for crop and soil conservation planning on La Colacha (Río Cuarto, Province of Cordoba, Argentina)

Agro-areas of Arroyos Menores (La Colacha) west and south of Rand south of R?o Cuarto (Prov. of Cordoba, Argentina) basins are very fertile but have high soil loses. Extreme rain events, inundations and other severe erosions forming gullies demand urgently actions in this area to avoid soil degradation and erosion supporting good levels of agro production. The authors first improved hydrologic data on La Colacha, evaluated the systems of soil uses and actions that could be recommended considering the relevant aspects of the study area and applied decision support systems (DSS) with mathematic tools for planning of defences and uses of soils in these areas. These were conducted here using multi-criteria models, in multi-criteria decision making (MCDM); first of discrete MCDM to chose among global types of use of soils, and then of continuous MCDM to evaluate and optimize combined actions, including repartition of soil use and the necessary levels of works for soil conservation and for hydraulic management to conserve against erosion these basins. Relatively global solutions for La Colacha area have been defined and were optimised by Linear Programming in Goal Programming forms that are presented as Weighted or Lexicographic Goal Programming and as Compromise Programming. The decision methods used are described, indicating algorithms used, and examples for some representative scenarios on La Colacha area are given.

Carbon allocation in north-western Amazon forests (Colombia)

Los estudios sobre la asignación del carbono en los ecosistemas forestales proporcionan información esencial para la comprensión de las diferencias espaciales y temporales en el ciclo del carbono de tal forma que pueden aportar información a los modelos y, así predecir las posibles respuestas de los bosques a los cambios en el clima. Dentro de este contexto, los bosques Amazónicos desempeñan un papel particularmente importante en el balance global del carbono; no obstante, existen grandes incertidumbres en cuanto a los controles abióticos en las tasas de la producción primaria neta (PPN), la asignación de los productos de la fotosíntesis a los diferentes componentes o compartimentos del ecosistema (aéreo y subterráneo) y, cómo estos componentes de la asignación del carbono responden a eventos climáticos extremos. El objetivo general de esta tesis es analizar los componentes de la asignación del carbono en bosques tropicales maduros sobre suelos contrastantes, que crecen bajo condiciones climáticas similares en dos sitios ubicados en la Amazonia noroccidental (Colombia): el Parque Natural Nacional Amacayacu y la Estación Biológica Zafire. Con este objetivo, realicé mediciones de los componentes de la asignación del carbono (biomasa, productividad primaria neta, y su fraccionamiento) a nivel ecosistémico y de la dinámica forestal (tasas anuales de mortalidad y reclutamiento), a lo largo de ocho años (20042012) en seis parcelas permanentes de 1 hectárea establecidas en cinco tipos de bosques sobre suelos diferentes (arcilloso, franco-arcilloso, franco-arcilloso-arenoso, franco-arenoso y arena-francosa). Toda esta información me permitió abordar preguntas específicas que detallo a continuación. En el Capítulo 2 evalúe la hipótesis de que a medida que aumenta la fertilidad del suelo disminuye la cantidad del carbono asignado a la producción subterránea (raíces finas con diámetro <2 mm). Y para esto, realicé mediciones de la masa y la producción de raíces finas usando dos métodos: (1) el de los cilindros de crecimiento y, (2) el de los cilindros de extracción secuencial. El monitoreo se realizó durante 2.2 años en los bosques con suelos más contrastantes: arcilla y arena-francosa. Encontré diferencias significativas en la masa de raíces finas y su producción entre los bosques y, también con respecto a la profundidad del suelo (010 y 1020 cm). El bosque sobre arena-francosa asignó más carbono a las raíces finas que el bosque sobre arcillas. La producción de raíces finas en el bosque sobre arena-francosa fue dos veces más alta (media ± error estándar = 2.98 ± 0.36 y 3.33 ± 0.69 Mg C ha1 año1, con el método 1 y 2, respectivamente), que para el bosque sobre arcillas, el suelo más fértil (1.51 ± 0.14, método 1, y desde 1.03 ± 0.31 a 1.36 ± 0.23 Mg C ha1 año1, método 2). Del mismo modo, el promedio de la masa de raíces finas fue tres veces mayor en el bosque sobre arena-francosa (5.47 ± 0.17 Mg C ha1) que en el suelo más fértil (de 1.52 ± 0.08 a 1.82 ± 0.09 Mg C ha1). La masa de las raíces finas también mostró un patrón temporal relacionado con la lluvia, mostrando que la producción de raíces finas disminuyó sustancialmente en el período seco del año 2005. Estos resultados sugieren que los recursos del suelo pueden desempeñar un papel importante en los patrones de la asignación del carbono entre los componentes aéreo y subterráneo de los bosques tropicales; y que el suelo no sólo influye en las diferencias en la masa de raíces finas y su producción, sino que también, en conjunto con la lluvia, sobre la estacionalidad de la producción. En el Capítulo 3 estimé y analicé los tres componentes de la asignación del carbono a nivel del ecosistema: la biomasa, la productividad primaria neta PPN, y su fraccionamiento, en los mismos bosques del Capítulo 2 (el bosque sobre arcillas y el bosque sobre arena-francosa). Encontré diferencias significativas en los patrones de la asignación del carbono entre los bosques; el bosque sobre arcillas presentó una mayor biomasa total y aérea, así como una PPN, que el bosque sobre arena-francosa. Sin embargo, la diferencia entre los dos bosques en términos de la productividad primaria neta total fue menor en comparación con las diferencias entre la biomasa total de los bosques, como consecuencia de las diferentes estrategias en la asignación del carbono a los componentes aéreo y subterráneo del bosque. La proporción o fracción de la PPN asignada a la nueva producción de follaje fue relativamente similar entre los dos bosques. Nuestros resultados de los incrementos de la biomasa aérea sugieren una posible compensación entre la asignación del carbono al crecimiento de las raíces finas versus el de la madera, a diferencia de la compensación comúnmente asumida entre la parte aérea y la subterránea en general. A pesar de estas diferencias entre los bosques en términos de los componentes de la asignación del carbono, el índice de área foliar fue relativamente similar entre ellos, lo que sugiere que el índice de área foliar es más un indicador de la PPN total que de la asignación de carbono entre componentes. En el Capítulo 4 evalué la variación espacial y temporal de los componentes de la asignación del carbono y la dinámica forestal de cinco tipos e bosques amazónicos y sus respuestas a fluctuaciones en la precipitación, lo cual es completamente relevante en el ciclo global del carbono y los procesos biogeoquímicos en general. Estas variaciones son así mismo importantes para evaluar los efectos de la sequía o eventos extremos sobre la dinámica natural de los bosques amazónicos. Evalué la variación interanual y la estacionalidad de los componentes de la asignación del carbono y la dinámica forestal durante el periodo 2004−2012, en cinco bosques maduros sobre diferentes suelos (arcilloso, franco-arcilloso, franco-arcilloso-arenoso, franco-arenoso y arena-francosa), todos bajo el mismo régimen local de precipitación en la Amazonia noroccidental (Colombia). Quería examinar sí estos bosques responden de forma similar a las fluctuaciones en la precipitación, tal y como pronostican muchos modelos. Consideré las siguientes preguntas: (i) ¿Existe una correlación entre los componentes de la asignación del carbono y la dinámica forestal con la precipitación? (ii) ¿Existe correlación entre los bosques? (iii) ¿Es el índice de área foliar (LAI) un indicador de las variaciones en la producción aérea o es un reflejo de los cambios en los patrones de la asignación del carbono entre bosques?. En general, la correlación entre los componentes aéreo y subterráneo de la asignación del carbono con la precipitación sugiere que los suelos juegan un papel importante en las diferencias espaciales y temporales de las respuestas de estos bosques a las variaciones en la precipitación. Por un lado, la mayoría de los bosques mostraron que los componentes aéreos de la asignación del carbono son susceptibles a las fluctuaciones en la precipitación; sin embargo, el bosque sobre arena-francosa solamente presentó correlación con la lluvia con el componente subterráneo (raíces finas). Por otra parte, a pesar de que el noroeste Amazónico es considerado sin una estación seca propiamente (definida como <100 mm meses −1), la hojarasca y la masa de raíces finas mostraron una alta variabilidad y estacionalidad, especialmente marcada durante la sequía del 2005. Además, los bosques del grupo de suelos francos mostraron que la hojarasca responde a retrasos en la precipitación, al igual que la masa de raíces finas del bosque sobre arena-francosa. En cuanto a la dinámica forestal, sólo la tasa de mortalidad del bosque sobre arena-francosa estuvo correlacionada con la precipitación (ρ = 0.77, P <0.1). La variabilidad interanual en los incrementos en el tallo y la biomasa de los individuos resalta la importancia de la mortalidad en la variación de los incrementos en la biomasa aérea. Sin embargo, las tasas de mortalidad y las proporciones de individuos muertos por categoría de muerte (en pie, caído de raíz, partido y desaparecido), no mostraron tendencias claras relacionadas con la sequía. Curiosamente, la hojarasca, el incremento en la biomasa aérea y las tasas de reclutamiento mostraron una alta correlación entre los bosques, en particular dentro del grupo de los bosques con suelos francos. Sin embargo, el índice de área foliar estimado para los bosques con suelos más contrastantes (arcilla y arena-francosa), no presentó correlación significativa con la lluvia; no obstante, estuvo muy correlacionado entre bosques; índice de área foliar no reflejó las diferencias en la asignación de los componentes del carbono, y su respuesta a la precipitación en estos bosques. Por último, los bosques estudiados muestran que el noroeste amazónico es susceptible a fenómenos climáticos, contrario a lo propuesto anteriormente debido a la ausencia de una estación seca propiamente dicha. ABSTRACT Studies of carbon allocation in forests provide essential information for understanding spatial and temporal differences in carbon cycling that can inform models and predict possible responses to changes in climate. Amazon forests play a particularly significant role in the global carbon balance, but there are still large uncertainties regarding abiotic controls on the rates of net primary production (NPP) and the allocation of photosynthetic products to different ecosystem components; and how the carbon allocation components of Amazon forests respond to extreme climate events. The overall objective of this thesis is to examine the carbon allocation components in old-growth tropical forests on contrasting soils, and under similar climatic conditions in two sites at the Amacayacu National Natural Park and the Zafire Biological Station, located in the north-western Amazon (Colombia). Measurements of above- and below-ground carbon allocation components (biomass, net primary production, and its partitioning) at the ecosystem level, and dynamics of tree mortality and recruitment were done along eight years (20042012) in six 1-ha plots established in five Amazon forest types on different soils (clay, clay-loam, sandy-clay-loam, sandy-loam and loamy-sand) to address specific questions detailed in the next paragraphs. In Chapter 2, I evaluated the hypothesis that as soil fertility increases the amount of carbon allocated to below-ground production (fine-roots) should decrease. To address this hypothesis the standing crop mass and production of fine-roots (<2 mm) were estimated by two methods: (1) ingrowth cores and, (2) sequential soil coring, during 2.2 years in the most contrasting forests: the clay-soil forest and the loamy-sand forest. We found that the standing crop fine-root mass and its production were significantly different between forests and also between soil depths (0–10 and 10–20 cm). The loamysand forest allocated more carbon to fine-roots than the clay-soil forest, with fine-root production in the loamy-sand forest twice (mean ± standard error = 2.98 ± 0.36 and 3.33 ± 0.69 Mg C ha −1 yr −1, method 1 and 2, respectively) as much as for the more fertile claysoil forest (1.51 ± 0.14, method 1, and from 1.03 ± 0.31 to 1.36 ± 0.23 Mg C ha −1 yr −1, method 2). Similarly, the average of standing crop fine-root mass was three times higher in the loamy-sand forest (5.47 ± 0.17 Mg C ha1) than in the more fertile soil (from 1.52 ± 0.08 a 1.82 ± 0.09 Mg C ha1). The standing crop fine-root mass also showed a temporal pattern related to rainfall, with the production of fine-roots decreasing substantially in the dry period of the year 2005. These results suggest that soil resources may play an important role in patterns of carbon allocation of below-ground components, not only driven the differences in the biomass and its production, but also in the time when it is produced. In Chapter 3, I assessed the three components of stand-level carbon allocation (biomass, NPP, and its partitioning) for the same forests evaluated in Chapter 2 (clay-soil forest and loamy-sand forest). We found differences in carbon allocation patterns between these two forests, showing that the forest on clay-soil had a higher aboveground and total biomass as well as a higher above-ground NPP than the loamy-sand forest. However, differences between the two types of forests in terms of stand-level NPP were smaller, as a consequence of different strategies in the carbon allocation of above- and below-ground components. The proportional allocation of NPP to new foliage production was relatively similar between the two forests. Our results of aboveground biomass increments and fine-root production suggest a possible trade-off between carbon allocation to fine-roots versus wood growth (as it has been reported by other authors), as opposed to the most commonly assumed trade-off between total above- and below-ground production. Despite these differences among forests in terms of carbon allocation components, the leaf area index showed differences between forests like total NPP, suggesting that the leaf area index is more indicative of total NPP than carbon allocation. In Chapter 4, I evaluated the spatial and temporal variation of carbon allocation components and forest dynamics of Amazon forests as well as their responses to climatic fluctuations. I evaluated the intra- and inter-annual variation of carbon allocation components and forest dynamics during the period 2004−2012 in five forests on different soils (clay, clay-loam, sandy-clay-loam, sandy-loam and loamy-sand), but growing under the same local precipitation regime in north-western Amazonia (Colombia). We were interested in examining if these forests respond similarly to rainfall fluctuations as many models predict, considering the following questions: (i) Is there a correlation in carbon allocation components and forest dynamics with precipitation? (ii) Is there a correlation among forests? (iii) Are temporal responses in leaf area index (LAI) indicative of variations of above-ground production or a reflection of changes in carbon allocation patterns among forests?. Overall, the correlation of above- and below-ground carbon allocation components with rainfall suggests that soils play an important role in the spatial and temporal differences of responses of these forests to rainfall fluctuations. On the one hand, most forests showed that the above-ground components are susceptible to rainfall fluctuations; however, there was a forest on loamy-sand that only showed a correlation with the below-ground component (fine-roots). On the other hand, despite the fact that north-western Amazonia is considered without a conspicuous dry season (defined as <100 mm month−1), litterfall and fine-root mass showed high seasonality and variability, particularly marked during the drought of 2005. Additionally, forests of the loam-soil group showed that litterfall respond to time-lags in rainfall as well as and the fine-root mass of the loamy-sand forest. With regard to forest dynamics, only the mortality rate of the loamy-sand forest was significantly correlated with rainfall (77%). The observed inter-annual variability of stem and biomass increments of individuals highlighted the importance of the mortality in the above-ground biomass increment. However, mortality rates and death type proportion did not show clear trends related to droughts. Interestingly, litterfall, above-ground biomass increment and recruitment rates of forests showed high correlation among forests, particularly within the loam-soil forests group. Nonetheless, LAI measured in the most contrasting forests (clay-soil and loamysand) was poorly correlated with rainfall but highly correlated between forests; LAI did not reflect the differences in the carbon allocation components, and their response to rainfall on these forests. Finally, the forests studied highlight that north-western Amazon forests are also susceptible to climate fluctuations, contrary to what has been proposed previously due to their lack of a pronounced dry season.

Localization and Tracking in Energy-Constrained Networks with Dynamic Connectivity

Systems used for target localization, such as goods, individuals, or animals, commonly rely on operational means to meet the final application demands. However, what would happen if some means were powered up randomly by harvesting systems? And what if those devices not randomly powered had their duty cycles restricted? Under what conditions would such an operation be tolerable in localization services? What if the references provided by nodes in a tracking problem were distorted? Moreover, there is an underlying topic common to the previous questions regarding the transfer of conceptual models to reality in field tests: what challenges are faced upon deploying a localization network that integrates energy harvesting modules? The application scenario of the system studied is a traditional herding environment of semi domesticated reindeer (Rangifer tarandus tarandus) in northern Scandinavia. In these conditions, information on approximate locations of reindeer is as important as environmental preservation. Herders also need cost-effective devices capable of operating unattended in, sometimes, extreme weather conditions. The analyses developed are worthy not only for the specific application environment presented, but also because they may serve as an approach to performance of navigation systems in absence of reasonably accurate references like the ones of the Global Positioning System (GPS). A number of energy-harvesting solutions, like thermal and radio-frequency harvesting, do not commonly provide power beyond one milliwatt. When they do, battery buffers may be needed (as it happens with solar energy) which may raise costs and make systems more dependent on environmental temperatures. In general, given our problem, a harvesting system is needed that be capable of providing energy bursts of, at least, some milliwatts. Many works on localization problems assume that devices have certain capabilities to determine unknown locations based on range-based techniques or fingerprinting which cannot be assumed in the approach considered herein. The system presented is akin to range-free techniques, but goes to the extent of considering very low node densities: most range-free techniques are, therefore, not applicable. Animal localization, in particular, uses to be supported by accurate devices such as GPS collars which deplete batteries in, maximum, a few days. Such short-life solutions are not particularly desirable in the framework considered. In tracking, the challenge may times addressed aims at attaining high precision levels from complex reliable hardware and thorough processing techniques. One of the challenges in this Thesis is the use of equipment with just part of its facilities in permanent operation, which may yield high input noise levels in the form of distorted reference points. The solution presented integrates a kinetic harvesting module in some nodes which are expected to be a majority in the network. These modules are capable of providing power bursts of some milliwatts which suffice to meet node energy demands. The usage of harvesting modules in the aforementioned conditions makes the system less dependent on environmental temperatures as no batteries are used in nodes with harvesters--it may be also an advantage in economic terms. There is a second kind of nodes. They are battery powered (without kinetic energy harvesters), and are, therefore, dependent on temperature and battery replacements. In addition, their operation is constrained by duty cycles in order to extend node lifetime and, consequently, their autonomy. There is, in turn, a third type of nodes (hotspots) which can be static or mobile. They are also battery-powered, and are used to retrieve information from the network so that it is presented to users. The system operational chain starts at the kinetic-powered nodes broadcasting their own identifier. If an identifier is received at a battery-powered node, the latter stores it for its records. Later, as the recording node meets a hotspot, its full record of detections is transferred to the hotspot. Every detection registry comprises, at least, a node identifier and the position read from its GPS module by the battery-operated node previously to detection. The characteristics of the system presented make the aforementioned operation own certain particularities which are also studied. First, identifier transmissions are random as they depend on movements at kinetic modules--reindeer movements in our application. Not every movement suffices since it must overcome a certain energy threshold. Second, identifier transmissions may not be heard unless there is a battery-powered node in the surroundings. Third, battery-powered nodes do not poll continuously their GPS module, hence localization errors rise even more. Let's recall at this point that such behavior is tight to the aforementioned power saving policies to extend node lifetime. Last, some time is elapsed between the instant an identifier random transmission is detected and the moment the user is aware of such a detection: it takes some time to find a hotspot. Tracking is posed as a problem of a single kinetically-powered target and a population of battery-operated nodes with higher densities than before in localization. Since the latter provide their approximate positions as reference locations, the study is again focused on assessing the impact of such distorted references on performance. Unlike in localization, distance-estimation capabilities based on signal parameters are assumed in this problem. Three variants of the Kalman filter family are applied in this context: the regular Kalman filter, the alpha-beta filter, and the unscented Kalman filter. The study enclosed hereafter comprises both field tests and simulations. Field tests were used mainly to assess the challenges related to power supply and operation in extreme conditions as well as to model nodes and some aspects of their operation in the application scenario. These models are the basics of the simulations developed later. The overall system performance is analyzed according to three metrics: number of detections per kinetic node, accuracy, and latency. The links between these metrics and the operational conditions are also discussed and characterized statistically. Subsequently, such statistical characterization is used to forecast performance figures given specific operational parameters. In tracking, also studied via simulations, nonlinear relationships are found between accuracy and duty cycles and cluster sizes of battery-operated nodes. The solution presented may be more complex in terms of network structure than existing solutions based on GPS collars. However, its main gain lies on taking advantage of users' error tolerance to reduce costs and become more environmentally friendly by diminishing the potential amount of batteries that can be lost. Whether it is applicable or not depends ultimately on the conditions and requirements imposed by users' needs and operational environments, which is, as it has been explained, one of the topics of this Thesis.

Estrategias de desarrollo sostenible de la arquitectura del oasis de M’hamid, desierto del Sahara

Esta investigación se plantea con la hipótesis radical de cómo habitar el desierto de forma sostenible, desde una actitud pragmática y experimental basada en el progreso. La justificación se basa en primer lugar en los 2.000 millones de personas en el mundo que viven en entornos desérticos, el 80% de ellas, en países en desarrollo, porque el 40% de la superficie terrestre está bajo amenaza de desertificación afectando al 37% de la población mundial, con 12 millones de hectáreas al año perdidas por esa causa, y por último, porque se considera el desierto como un entorno de gran atractivo y potencial. El contenido de la investigación se estructura en tres movimientos: posicionamiento, mirada y acción: Desde el posicionamiento se define en primer lugar la sostenibilidad, aportando un nuevo diagrama donde se incorpora el ámbito arquitectónico como uno de los pilares principales, y, posteriormente, se establecen los criterios de evaluación de la sostenibilidad, aportando un sistema de indicadores donde se incorporan parámetros adecuados a las circunstancias del oasis. Del mismo modo, se estudian y analizan metodologías de actuación y proyectos de desarrollo sostenible existentes que enmarcan el estado del arte, constatando la dificultad de adaptación de los mismos a las condiciones de los oasis, por lo que se elabora una metodología propia donde se modifica la dinámica estratégica, de forma que el impulso se plantea desde la acción social, a través de hipótesis de estrategias basadas en sistemas low-cost, autoconstruidas, asumibles económicamente y de implantación factible. El caso de estudio específico radica en la situación extrema de las condiciones en el oasis de M’hamid, donde se evidencia un proceso de desintegración y abandono. Esto es debido a una acumulación de circunstancias externas e internas, de múltiples factores: naturales y antrópicos que afectan al oasis, llevando al extremo las condiciones climáticas y la escasez de recursos, naturales y artificiales. Factores como el cambio climático, la sequía, los cambios en las políticas del agua, la amenaza de desertificación, los conflictos sociales, el desequilibrio ecológico, la escasez económica, la crisis energética, la obsolescencia arquitectónica, el patrimonio construido prácticamente destruido, y la malentendida nueva arquitectura. Es importante constatar la escasa documentación gráfica existente sobre la zona de actuación lo que ha conllevado un amplio trabajo de documentación, tanto cartográfica como de observación directa, aportada a la tesis como investigación de elaboración propia. La mirada analítica al caso de estudio permite conocer los recursos disponibles y las potencialidades latentes del oasis de M’hamid, que permitirán actuar para subvertir la dinámica involutiva imperante, de forma que los dibujos iniciales de apropiación contextual y análisis críticos derivan en mapas de acción diagramados conformados por un sistema de objetos y la definición de estrategias transversales, deconstruyendo el pasado y reconstruyendo el futuro, incorporando sistemas alternativos que se definen en 7 líneas estratégicas de acción formuladas desde los 3 ámbitos relacionados con el ecosistema: ecológico, socio- económico y arquitectónico. Así, la tesis defiende la acción arquitectónica como impulsora del desarrollo sostenible, apoyada en 3 elementos: - la creación de objetos “tecnoartesanos”, para el aprovechamiento de los recursos energéticos - las transformaciones arquitectónicas, para reformular el hábitat desde la eficiencia energética y el progreso - y el impulso de acciones cotidianas, que redefinan las relaciones sociales, creando entornos cooperativos y colaborativos. En el ámbito ecológico se proponen actuaciones anti desertificación mediante incubadoras de árboles; sistemas alternativos de gestión del agua, como la lluvia sólida; estrategias de potenciación de la producción agrícola; la construcción de mecanismos de obtención de energía a partir de residuos, como los paneles solares con botellas PET. En el ámbito socioeconómico se plantean nuevas formas de acción social y de reactivación económica. Por último, en el ámbito urbano-arquitectónico, se incorporan modificaciones morfológicas a la arquitectura existente y una relectura contemporánea de la tierra, como material que permite nuevas geometrías, obteniendo arena petrificada por procesos microbiológicos, y potenciando la tierra como recurso artístico. Esta tesis es un punto de partida, recoge sistemas, estrategias y experiencias, para funcionar como un estímulo o impulso dinamizador del futuro desarrollo sostenible del oasis, abriendo vías de investigación y experimentación. ABSTRACT This research puts forth the radical hypothesis of how to inhabit the desert in a sustainable way, using a pragmatic and experimental approach based on progress. The justification for this resides in the fact that there are 2,000 million people in the world living in desert environments, 80% of them in developing countries. Forty percent of the earth’s surface is under threat of desertification, affecting 37% of the world population and with 12 million hectares being lost each year. And finally, the desert is considered as an attractive environment and therefore, with great potential. The content of the research is structured in three main sections: positioning, observation and action: As a point of departure, sustainability is defined, proposing a new framework where architecture is incorporated as one of the main pillars. Then, the criteria for evaluating sustainability are established. These provide a system of indicators, which incorporate parameters based on the specific circumstances of the oasis. Methodologies and existing sustainable development projects that represent the state-of-the-art are analyzed, discussing the difficulty of adapting them to conditions of oases. A methodology that modifies strategic concepts is developed, whereby the catalyst is social action, and strategies are developed based on low-cost, self-built, and feasible implementation systems. The specific case study lies in the extreme conditions in the oasis of M'hamid, where a process of decay and neglect is evident. This deterioration is due to an accumulation of external and internal circumstances, and of natural and anthropogenic factors that affect the oasis, leading to extreme weather conditions and a shortage of both natural and artificial resources. Factors include; climate change, drought, changes in water policies, the threat of desertification, social conflicts, ecological imbalance, economic shortage, the energy crisis, architectural obsolescence, destruction of built heritage, and misunderstood new architecture. It is important to note the extremely limited graphic information about the area has led me to produce an extensive archive of maps and drawings, many developed by direct observation, that contribute to the research. The case study analysis of the oasis of M'hamid examines the resources available and the latent potential to slow the prevailing trend towards deterioration. The initial drawings of contextual appropriation and critical analysis result in maps and diagrams of action, which are formed by a system of objects and the definition of strategies. These can be thought of as understanding or “deconstructing” the past to reconstruct the future. Alternative approaches defined in seven strategies for action are based on three fields related to the ecosystem: ecological, socioeconomic and architectural. Thus, the thesis defends architectural action to promote sustainable development, based on three elements: - The creation of "techno-artisans", to make use of energy resources - Architectural changes, to reformulate habitat in terms of energy efficiency and progress - And the promotion of everyday actions, to redefine social relations, creating cooperative and collaborative environments. In the ecological field, I propose anti-desertification actions such as; tree incubators, alternative water management systems(such as solid rain),; strategies to empower the agricultural production, energy from low-cost systems made out from recycled materials(such as solar panels from PET bottles or wind turbine from bicycle wheels). In the socioeconomic sphere, I propose to implement new forms of social action and economic regeneration. Finally, within the urban and architectural field, I propose morphological changes to the existing architecture and a contemporary reinterpretation of the earth as a material that allows new geometries, creating petrified sand by microbiological processes or enhancing nature as an artistic and energy resource. This thesis is a starting point. It collects systems, strategies and experiences to serve as a stimulus or dynamic momentum for future sustainable development of the oasis, opening new avenues of research and experimentation. RÉSUMÉ Cette recherche part d'une hypothèse radicale : comment habiter le désert de façon durable, et ce à partir d'une approche pragmatique et expérimentale basée sur le progrès. Cette hypothèse se justifie en raison des 2 milliards de personnes qui dans le monde habitent des environnements désertiques, 80% d'entre eux dans des pays en voie de développement, mais aussi parce que 40% de la surface de la planète est sous menace de désertification, un phénomène affectant 37% de la population mondiale et qui cause la perte de 12 millions d'hectares par an; et enfin parce que le désert est considéré comme un environnement très attrayant et fort d’un grand potentiel. Le contenu de la recherche se divise en trois mouvements: le positionnement, le regard et l'action : Du point de vue du positionnement on définit tout d'abord la durabilité, présentant un nouveau schéma où le domaine de l'architecture devient un des principaux piliers, et, par la suite, des critères d'évaluation de la durabilité sont établis, en fournissant un système d’indicateurs qui intègre les paramètres appropriés aux circonstances de l'oasis. De même, des méthodologies et des projets de développement durable existants sont étudiés et analysés, ce qui encadre l'état de l'art, remarquant la difficulté de les adapter aux conditions des oasis. De cette difficulté découle l'élaboration d'une méthodologie qui modifie la dynamique stratégique, de sorte que l'impulsion provient de l'action sociale, à travers des hypothèses de stratégie basées sur des systèmes low-cost, auto-construits, et de mise en oeuvre économiquement viable. Le cas d'étude spécifique réside en la situation extrême des conditions de l'oasis de M’hamid, où un processus de décadence et de négligence est évident. Cela est dû à une accumulation de circonstances externes et internes, de multiples facteurs: les facteurs naturels et anthropiques qui affectent l'oasis, menant à l'extrême les conditions météorologiques et la pénurie de ressources, autant naturelles qu'artificielles. Des facteurs tels que le changement climatique, la sécheresse, les changements dans les politiques de l'eau, la menace de la désertification, les conflits sociaux, le déséquilibre écologique, la pénurie économique, la crise de l'énergie, l'obsolescence architecturale, le patrimoine bâti pratiquement détruit et une mauvais compréhensif de la nouvelle architecture. Il est important de de faire remarquer le peu d'informations graphiques du domaine d'action, ce qui a conduit à un vaste travail de documentation, autant cartographique que relative à l'observation directe. Cette documentation s'ajoute à la thèse en tant que recherche propre. Le regard analytique sur le cas d'étude permet de connaître les ressources disponibles et le potentiel latent de l'oasis de M’hamid, qui agiront pour renverser la dynamique d'involution en vigueur. Ainsi, les premiers dessins d'appropriation contextuelle et analyse critique deviennent des cartes d'action schématisées formées par un système d'objets et la définition de stratégies transversales, qui déconstruisent le passé et reconstruisent l'avenir, en incorporant des systèmes alternatifs qui se définissent sur 7 lignes stratégiques d'action formulées à partir des 3 domaines en relation avec l’écosystème: l’écologique, le socio-économique et l'architectural. Ainsi, la thèse défend l'action architecturale en tant que promotrice du développement durable, et ce basé sur 3 éléments: - la création d'objets "technoartisans" pour l'exploitation des ressources énergétiques - les modifications architecturales, pour reformuler l'habitat du point de vue de l'efficacité énergétique et le progrès - et la promotion des actions quotidiennes, pour redéfinir les relations sociales, et la création d'environnements de coopération et collaboration. Dans le domaine de l'écologie des actions de lutte contre la désertification sont proposées à travers des pépinières d'arbres, des systèmes alternatifs de gestion de l'eau comme par exemple la pluie solide, des stratégies de mise en valeur de la production agricole, la construction de mécanismes de production d'énergie à partir de résidus, tels que les panneaux solaires ou les bouteilles en PET. Dans le domaine socio-économique, l'on propose de nouvelles formes d'action sociale et de reprise économique. Enfin, dans le domaine de l'urbain et de l'architectural, on incorpore des changements morphologiques à l'architecture existante et une relecture contemporaine de la terre, comme matériau qui permet de nouvelles géométries, en obtenant du sable pétrifié par des procédés microbiologiques et en mettant en valeur la terre comme une ressource artistique. Cette thèse n'est qu'un point de départ. Elle recueille des systèmes, des stratégies et des expériences pour servir de stimulus ou d'impulsion dynamisatrice du futur développement durable de l'oasis, en ouvrant des voies de recherche et d'expérimentation.

Metodología para la gestión integral de las presas de laminación de avenidas y su aplicación a la cuenca hidrográfica del Segura

En el levante español se producen periódicamente intensos aguaceros (gota fría), que generan grandes riadas, desbordándose los cauces y asolando los campos y las ciudades, ocasionando graves daños en la economía local y con frecuencia, por desgracia, víctimas personales. La Confederación Hidrográfica del Segura ha puesto en marcha un vasto sistema de protección, conocido como Plan de Defensa contra Avenidas, del que ya se encuentran en explotación un conjunto de presas cuyo objetivo prioritario es la laminación de las avenidas. Las presas de laminación ubicadas en esta área mediterránea son estructuras muy singulares, al estar ubicadas en cuencas extremadamente secas, con alta pendiente, rápida respuesta, picos altos de caudal, y gran poder erosivo del flujo. Las aguas arrastran en suspensión un alto porcentaje de aporte sólido y flotantes, que quedan retenidos en el embalse, aterrándolo e inutilizando los desagües. En esta tesis doctoral se analizan los criterios de actuación para la gestión de estas presas de laminación, con objeto de que se puedan introducir en las Normas de Explotación innovaciones destinadas a mejorar la eficiencia del conjunto, de manera que se consiga la máxima protección posible y al mismo tiempo se puedan aprovechar las aguas, sin menoscabo de su objetivo prioritario, para otros fines complementarios. Como consecuencia del trabajo realizado se indica la conveniencia de establecer un conjunto de normas de actuación comunes a todas las presas del sistema, como es la estrategia de recibir siempre a los hidrogramas de la riada con las compuertas de los desagües de fondo cerrados, o la conveniencia de que en todas las presas se dispongan compuertas en estos órganos. También se dictan recomendaciones en la gestión del vaciado, para conseguir el máximo aprovechamiento del agua, introduciendo el concepto innovador de los trasvases virtuales. Asimismo, se analiza la conveniencia de fijar normas diferenciales específicas atendiendo a las peculiaridades de cada presa, en cuanto se refiere al nivel máximo de explotación, al cumplimiento de los condicionantes ambientales, al mantenimiento de la calidad del agua, y a otros aspectos singulares que caracterizan a cada uno de estos embalses. The Spanish Mediterranean region hydrology is characterised by low rainfall, but concentrated in extreme convective events. Those heavy rains and storms lead to large, flash-floods which cause devastation of fields, villages and, unfortunately, loss of lives. Segura River Basin Authority has developed an ambitious plan for flood protection and control that is constituted by a system of flood protection dams, river channelling, river diversions diversions and levees. Flood protection dams placed on this area, are distinct structures, as they are located on extremely dry basins, with high slopes and limited vegetal covering. These facts, along with the very high rainfall intensity, are determinants of a rapid response and a very erosive flow. The flow transports a large rate of solids in suspension, and also debris, which many times block and clog the outlets intakes, disabling them. In such a case, the dam would be inoperative, in an emergency state and remedial measures should be taken. This PhD thesis analyses the flood protection dams operation criteria, for providing managers a methodology to analyse each individual case and also the flood protection system as a whole. Additionally practical rules and recommendations, to cope with the objectives of dam safety, flood protection and water resources use, are given. The rules consider the specific differences and risks that may be faced by the dams. To that end, they were grouped, depending on their characteristics: allowance for permanent water storage, environmental restrictions, water quality, geotechnical problems, type of structure, etc. As a result of this research, it is recommended to design these dams with valves for regulating the bottom outlets. The availability of valves is linked with the routing strategy of receiving flood with the outlets closed. This has been shown as the best measure to prevent clogging and opens the possibility of storing temporarily the water, making then a scheduled emptying of the reservoir, which could be computed as a virtual transfer to the regulating dams. Emptying should be done in accordance with the situation of the other dams of the system and of the rivers downstream. This detention time would make possible also the beginning of the sedimentation process which is necessary for using the water with the modern irrigation systems that are in use in this area.

Understanding extreme Spanish coastal flood events

The Santa Irene flood event, at the end of October 1982, is one of the most dramatically widely reported flood events in Spain. Its renown is mainly due to the collapse of the Tous dam, but its main message is to be the paradigm of the incidence of the maritime/littoral weather and its temporal sea level rise by storm surge accompanying rain process on the coastal plains inland floods. Looking at damages the presentation analyzes the adapted measures from the point of view of the aims of the FP7 SMARTeST Project related to the Flood Resilience improvement in urban areas through looking for Technologies, Systems and Tools an appropriate "road to de market".

Extreme pointer years in tree-ring records of central Spain as evidence of climatic events and the eruption of the Huaynaputina Volcano (Peru, 1600 AD)

The study of pointer years of numerous tree-ring chronologies of the central Iberian Peninsula (Sierra de Guadarrama) could provide complementary information about climate variability over the last 405 yr. In total, 64 pointer years have been identified: 30 negative (representing minimum growths) and 34 positive (representing maximum growths), the most significant of these being 1601, 1963 and 1996 for the negative ones, and 1734 and 1737 for the positive ones. Given that summer precipitation was found to be the most limiting factor for the growth of Pinus in the Sierra de Guadarrama in the second half of the 20th century, it is also an explanatory factor in almost 50% of the extreme growths. Furthermore, these pointer years and intervals are not evenly distributed throughout time. Both in the first half of the 17th and in the second half of 20th, they were more frequent and more extreme and these periods are the most notable for the frequency of negative pointer years in Central Spain. The interval 1600–1602 is of special significance, being one of the most unfavourable for tree growth in the centre of Spain, with 1601 representing the minimum index in the regional chronology. We infer that this special minimum annual increase was the effect of the eruption of Huaynaputina, which occurred in Peru at the beginning of 1600 AD. This is the first time that the effects of this eruption in the tree-ring records of Southern Europe have been demonstrated.

Change of extreme rainfall indexes at Ebro River Basin

The purpose of this work is to provide a description of the heavy rainfall phenomenon on statistical tools from a Spanish region. We want to quantify the effect of the climate change to verify the rapidity of its evolution across the variation of the probability distributions. Our conclusions have special interest for the agrarian insurances, which may make estimates of costs more realistically. In this work, the analysis mainly focuses on: The distribution of consecutive days without rain for each gauge stations and season. We estimate density Kernel functions and Generalized Pareto Distribution (GPD) for a network of station from the Ebro River basin until a threshold value u. We can establish a relation between distributional parameters and regional characteristics. Moreover we analyze especially the tail of the probability distribution. These tails are governed by law of power means that the number of events n can be expressed as the power of another quantity x : n(x) = x? . ? can be estimated as the slope of log-log plot the number of events and the size. The most convenient way to analyze n(x) is using the empirical probability distribution. Pr(X mayor que x) ? x-?. The distribution of rainfall over percentile of order 0.95 from wet days at the seasonal scale and in a yearly scale with the same treatment of tails than in the previous section.

Adaptation Strategies to Climate Change for summer crops on Andalusia: evaluation for extreme maximum temperatures

Evaluate a set of agricultural adaptation strategies to cope with climate change impacts, with focus on the consequences of extreme events on the adaptations proposed in the semi-arid environment of Andalusia (Southern Spain).