92 research outputs found
Distribution, trends, and drivers of flash droughts in the United Kingdom
Get PDFFlash droughts have been the subject of a great deal of scientific attention in the last decade, but the greatest emphasis has been on relatively dry climates. Here, we characterise this type of rapid-onset drought events in a more humid setting, the United Kingdom (UK), for the period 1969–2021. Our results show that flash droughts have affected both the wetter regions of the north-west and the drier regions of the south-east in every season over the last 5 decades. Nevertheless, the spatio-temporal distribution of flash droughts is highly variable in the UK, with important regional and seasonal contrasts. Central and northern regions are generally the most frequently affected by flash droughts in comparison to the south-eastern region. Overall, there are non-significant trends in the frequency of flash droughts in winter, summer, and autumn. However, we found a significant increase in the number of flash droughts recorded in spring. We also analysed the relative contribution of the atmospheric evaporative demand (AED) and precipitation to flash drought development in the UK. Our findings show that flash drought occurrence responds primarily to precipitation variability in all seasons but particularly in winter and autumn. In spring and summer, the AED is important as a secondary driver for triggering flash droughts, especially in the drier regions of the south-east. Furthermore, the trends observed in AED contribution evidence that its relevance is rising significantly in spring, also in the south-eastern UK in summer. The atmospheric and oceanic conditions related to flash drought development were also examined. Remarkable anomalies in sea level pressure and 500 hPa geopotential height associated with the presence of high-pressure systems are noted in all seasons during the development of the main flash droughts affecting the UK. Similarly, flash droughts typically develop under the negative phase of the North Atlantic Oscillation in winter and autumn, while in summer and spring the positive phase is dominant. We also found positive anomalies in sea surface temperature during the development of flash droughts in spring and summer, while mixed anomalies are observed in winter and autumn. This study presents a detailed characterisation of the flash drought phenomenon in the UK, providing useful information for drought assessment and management and a climatology of flash droughts that can be used as a baseline against which future changes in flash drought occurrence can be assessed
Geomorfología, geodiversidad y riesgos en el río Seco (cuenca del río Martín, Teruel)
Get PDFLos ríos efímeros se encuentran entre los cursos fluviales menos estudiados en los ámbitos científico y técnico. Sin embargo, no sólo representan un elemento de interés por su propio valor intrínseco, sino también por su problemática vinculada a los eventos de crecidas relámpago que generan situaciones de riesgo para la población. En el presente trabajo se aplica una propuesta metodológica hidrogeomorfológica al estudio de cursos efímeros, en concreto sobre el caso particular del río Seco (cuenca del río Martín, Teruel). Es un curso fluvial que destaca por su diversidad geomorfológica y que asistió a una crecida relámpago muy notable en 2013. Se ha realizado una detallada caracterización hidrogeomorfológica, aplicada al riesgo y a su representatividad y geodiversidad como curso efímero en la cuenca del Ebro
Conectivismo: Propuesta de las NTIC para la docencia
Get PDFEl conectivismo es un nuevo modelo teórico-explicativo que plantea un nuevo paradigma de aprendizaje y en el que la revolución tecnológica e informacional muestraque las personas están recibiendo un aprendizaje más activo, adaptando una visión más holistica que se centra en la comprensión integrada de la realidad compleja y multidimensional. se presentan medios pedagógicos, no todos pertenecientes a las Nuevas Teconologías de la Informativas y Comunicacionales (NTIC) que pueden favorecer la docencia en la era digital del siglo XXI
Déficit urbano-habitacional: Una aplicación a la comuna tres del municipio de Pasto, año 2011
Get PDFEl artículo pretende aportar a la validación de teorías sobre la estimación integral de deficiencias habitacionales que el déficit convencional de vivienda no logra capturar. La hipótesis fundamental es que las condiciones habitacionales evaluadas según el impacto en la calidad de vida, no se pueden considerar en ausencia de factores que afectan externamente al hogar, pues el hombre es un ser que encuentra su bienestar en la interacción con sus pares y el entorno. Se propone la estimación del Déficit Urbano-Habitacional que incluye la valoración del déficit de vivienda, pero también de la infraestructura, los servicios y el espacio público. Para validar lo anterior, se realizó una aplicación a la Comuna Tres del Municipio de Pasto. Los resultados indican que de los cuatro componentes que integran el Déficit Urbano-Habitacional, el déficit de servicios y el de espacios públicos resultan ser los más preocupantes
Evaluación y propuesta de mejora del tramo vial de 2.1 km de la vía a San Antonio de Gapal, ubicada en el cantón Cuenca provincia del Azuay
Get PDFSan Antonio de Gapal es una comunidad rural que posee dos vías que conectan con la zona urbana de Cuenca, una de ellas conecta con la vía a El Valle y la otra con la ciudadela Santa María del Vergel; en la primera existe un alto flujo vehicular con grandes tiempos de espera por lo cual se requiere una vía de desfogue. Debido a esto se decidió evaluar el tramo alterno que conecta con la ciudadela y proponer un diseño basado en normativas nacionales e internacionales. Se obtuvo como resultado un TPDA de 1492 vehículos livianos equivalentes del año 2024 y con proyección de tráfico futuro de 3255 V. L. E. para el año 2049. Se realizó el levantamiento topográfico a lo largo de los 2.1 km de vía, para el diseño de pavimentos se realizó un ensayo de suelos de 4 calicatas obteniendo un CBR promedio de 5.87%. Como resultado se obtuvo una propuesta de mejora al diseño geométrico de la vía presentado en planos, y una alternativa de diseño de pavimentos flexible, dando como resultado más favorable una estructura de pavimento asfáltico con un espesor de capa de rodadura de 8cm, base y subbase de 20cm y un mejoramiento de 5cm.Ingeniero Civi
A multidecadal assessment of climate indices over Europe
Get PDFMonitoring and management of several environmental and socioeconomic sectors require climate data that can be summarized using a set of standard and meaningful climate metrics. This study describes a newly developed gridded dataset for the whole of Europe, which employed a set of 125 climate indices spanning different periods based on data availability, but mainly 1950–2017 and 1979–2017. This dataset comprehensively summarizes climate variability in Europe for a wide range of climate variables and conditions, including air temperature, precipitation, biometeorology, aridity, continentality, drought, amongst others. Climate indices were computed at different temporal scales (i.e. monthly, seasonal and annual) and mapped at a grid interval of 0.25°. We intend to update these indices on an annual basis. This dataset is freely available to research and end-user communities
Global observations of land-atmosphere interactions during flash drought
Get PDFFlash droughts, which intensify on subseasonal-to-seasonal (S2S) timescales (2 weeks–2 months), cause severe and sudden impacts on agriculture, ecosystems and economies. To evaluate and improve S2S forecasts of flash drought, we need to understand the land-atmosphere coupling processes that are critical to flash drought development, specifically the feedbacks between soil moisture and evapotranspiration. Previous investigations of flash droughts have either focused on specific regions or relied on global reanalysis datasets, which have known shortcomings in their representation of land-atmosphere interactions. Here, we use a variety of global long-term products of daily satellite observations to explore the evolution of the surface energy balance during flash droughts over the period 2000–2020. We investigate the differences between flash droughts with stronger and weaker land-atmosphere coupling, and assess feedbacks from the land surface to near-surface air temperatures during the events. Events with stronger evaporative stress are associated with perturbations in the surface energy budget for 4 months both before and after drought onset, indicating the importance of precursor land conditions for S2S predictability. For three semi-arid regions in Africa, we show that increased sensible heat flux feeds back to increase peak air temperatures during flash droughts. We also use Vegetation Optical Depth (VOD), a proxy for vegetation water content, to demonstrate that lower VOD 1–2 months before flash drought onset is linked to increased air temperatures during the peak of the drought in some regions. For example, in West African summer, 12 % of flash droughts with precursor VOD anomalies in the highest quartile experience a peak air temperature anomaly > 1.5σ, whereas this increases to 27 % for events with precursor VOD anomalies in the lowest quartile. This shows that globally-observable land surface conditions could provide useful information to S2S forecasts and motivates further assessment of land-atmosphere interactions in these forecasting models using observational datasets at the global scale
Evaluation of long-term changes in precipitation over Bolivia based on observations and Coupled Model Intercomparison Project models
Get PDFUsing observations and model simulations from the 5th and 6th phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6, respectively), this study evaluated changes in monthly, seasonal, and annual precipitation over Bolivia from 1950 to 2019. Results demonstrate that observed precipitation is characterized by strong interannual and decadal variability. However, long-term precipitation trends were not identified on the annual scale. Similarly, changes in seasonal precipitation were almost nonsignificant (p > .05) for the study period. Spatially, albeit with its complex orography, no substantial regional variations in observed precipitation trends can be identified across Bolivia. In contrast, long-term precipitation trends, based on CMIP5 and CMIP6 models, suggest a dominance of negative trends, mainly during austral winter (JJA) (−10%) and spring (SON) (−15%). These negative trends were more pronounced in the lowlands of Bolivia (−20%). Overall, these contradictory results highlight the need for validating precipitation trend outputs from model simulations, especially in areas of complex topography like Bolivia.This work was sup-ported by the research projects CGL2017-82216-R,PCI2019-103631, and PID2019-108589RA-I00, financedby the Spanish Ministry of Science and FEDER, theCROSSDRO project financed by the AXIS (Assessment ofCross(X)-sectorial climate impacts and pathways for Sus-tainable transformation), the JPI-Climate co-funded callof the European Commission, and the LINCGLOBAL-CSIC project (INCGLO0023, RED-CLIMA)
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