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Floods are the most frequent of natural disasters, affecting millions of people across the globe every year. The anticipation and forecasting of floods at the global scale is crucial to preparing for severe events and providing early awareness where local flood models and warning services may not exist. As numerical weather prediction models continue to improve, operational centres are increasingly using the meteorological output from these to drive hydrological models, creating hydrometeorological systems capable of forecasting river flow and flood events at much longer lead times than has previously been possible. Furthermore, developments in, for example, modelling capabilities, data and resources in recent years have made it possible to produce global scale flood forecasting systems. In this paper, the current state of operational large scale flood forecasting is discussed, including probabilistic forecasting of floods using ensemble prediction systems. Six state-of-the-art operational large scale flood forecasting systems are reviewed, describing similarities and differences in their approaches to forecasting floods at the global and continental scale. Currently, operational systems have the capability to produce coarse-scale discharge forecasts in the medium-range and disseminate forecasts and, in some cases, early warning products, in real time across the globe, in support of national forecasting capabilities. With improvements in seasonal weather forecasting, future advances may include more seamless hydrological forecasting at the global scale, alongside a move towards multi-model forecasts and grand ensemble techniques, responding to the requirement of developing multi-hazard early warning systems for disaster risk reduction.

In the present paper adsorptive capacity to remove carotenes from a com oil by an Uruguayan montmorillonite modified by different treatments: exchange with Na+ ions (M-Na), acid-activation (Act), exchange with Ca2+ and pillaring with Keggin ions (Pile-Act), acid-activation and pillaring (Act Pil-Ca), is studied. Bleaching action of the Uruguayan modified montmorillonites is compared with two commercial days: Tonsil Optimum (Süd-Chemie) and montmorillonite of type K 10 (Aldrich). Our results demonstrate that Act and Pilc-Ca samples are so efficient bleaching clays as commercials but M-Na sample Is lower. Also, mixtures of Pilc-Ca with commercial clays, added together in one step or consecutively in two steps, are studied. These procedures do not improved the bleaching action. As conclusion, the modified clay Pilc-Ca allows to bleach a neutralized and degummed corn oil, giving an end product similar to edible commercial oils. Such effect is improved with the simultaneous action with activated clays. En este trabajo se estudia la capacidad de adsorción de los carotenos presentes en un aceite de maíz, de una montmorillonita uruguaya modificada por diferentes procedimientos: intercambiada con iones Na+ (M-Na), activada por ácido (Act), intercambiada con iones Ca2+ y pilareada con iones Keggin (Pilc-Ca), activada por ácidos y pilareada (Act Pilc-Ca) frente a dos arcillas comerciales: Tonsil Optimum de Süd-Chemie y una Montmorillonita tipo K 10 de Aldrich. Los resultados indican que la muestra Act y la Pilc-Ca son tan eficientes como las comerciales pero que la capacidad de la muestra M-Na es considerablemente menor. También se efectuó ensayos con mezclas de Pilc-Ca con las arcillas comerciales, colocadas simultáneamente (en una sola etapa) o agregadas de manera sucesiva (en dos etapas). Dichos procedimientos no mejoraron la eficiencia del blanqueo. En conclusión, la modificación Pilc-Ca permite blanquear un aceite de maíz neutralizado y desgomado a valores similares a los correspondientes a los aceites comestibles comerciales. Este efecto se mejora aún por la acción simultánea con arcillas activadas.