4. HYBAM: un observatorio para medir el impacto del Cambio Climático sobre la erosión y los flujos de sedimentos en la zona Andino-Amazónica

La cuenca Amazónica es la más grande del mundo. La instalación del observatorio HYBAM con una amplia red de estaciones hidrológicas ubicadas desde el piedemonte andino hasta el océano Atlántico permite, desde el 2003, la generación de registros periódicos y confiables (nivel del agua, caudal, concentración de sedimentos y otros parámetros físico-químicos de la calidad del agua) a lo largo de toda la cuenca. Hoy en día, el desarrollo de técnicas satelitales, como la altimetría, permite completar eficientemente los datos obtenidos por las redes de medición en los ríos. El recrudecimiento de eventos extremos en la Amazonia (Inundaciones, sequias,) por efecto del cambio climático actual asociado a un cambio acelerado de ocupación de los suelos (deforestación, prácticas agrícolas), tiene una incidencia directa sobre la producción sedimentarla. Conocer los flujos de materiales transportados por los ríos es esencial tanto para la navegación fluvial como para guiar la explotación de los recursos naturales (agua, petróleo, minerales), para conocer el transporte de partículas contaminantes o para diseñar infraestructuras.Le bassin de l’Amazone est le plus grand du monde. La mise en œuvre de l’observatoire HYBAM avec un vaste réseau de stations hydrologiques situées sur les contreforts des Andes jusqu’á l’océan Atlantique permet de générer, depuis 2003, des données régulières et fiables tout le long du bassin (hauteur d’eau, débit, concentration de sédiments et d’autres paramètres physico-chimiques de qualité de l’eau). De nos jours, la mise au point des techniques par satellite, tels que l’altimétrie, permet de compléter efficacement les données obtenues par les réseaux de mesure dans les rivières. L’intensification des événements extrêmes dans la région amazonienne (inondations, sécheresses), liés au changement climatique actuel associé á un changement rapide de l’utilisation des terres (déforestation, pratiques agricoles), ont un impact direct sur la production de sédiments. Connaître les flux de matières transportés par les rivières est essentiel pour la navigation fluviale ainsi que pour guider l’exploitation des ressources naturelles (eau, pétrole, minéraux), connaître le trajet de particules polluantes ou concevoir des infrastructures.The Amazon basin is the largest basin in the world. The implementation of the HYBAM observatory, which has installed a large network of hydrological stations located from the Andean foothills down to the Atlantic Ocean, allows since 2003, generate periodical and reliable records (such as water level, flow, sediment concentration and other physicochemical parameters of water quality) along the entire basin. Nowadays, the development of satellite techniques, (such as altimetry), makes it possible to efficiently complete the data obtained by the measurement networks in rivers. The intensification of extreme events in the Amazon region (floods, droughts) occurred as a result of the current Climate Change associated with a more rapid change of land use (deforestation, agricultural practices) have a direct impact on sediment production. It is essential to know the flows of the materials transported by rivers, both for river navigation as well as to guide the exploitation of natural resources (water, oil, minerals), to know the transport of particulate pollutants, or to design infrastructures

Climate variability and extreme drought in the upper Solimões River (western Amazon Basin): Understanding the exceptional 2010 drought

This work provides an initial overview of climate features and their related hydrological impacts during the recent extreme droughts (1995, 1998, 2005 and 2010) in the upper Solimes River (western Amazon), using comprehensive in situ discharge and rainfall datasets. The droughts are generally associated with positive SST anomalies in the tropical North Atlantic and weak trade winds and water vapor transport toward the upper Solimes, which, in association with increased subsidence over central and southern Amazon, explain the lack of rainfall and very low discharge values. But in 1998, toward the end of the 1997-98 El Nio event, the drought is more likely related to an anomalous divergence of water vapor in the western Amazon that is characteristic of a warm event in the Pacific. During the austral spring and winter of 2010, the most severe drought since the seventies has been registered in the upper Solimes. Its intensity and its length, when compared to the 2005 drought, can be explained by the addition of an El Nio in austral summer and a very warm episode in the Atlantic in boreal spring and summer. As in 2005, the lack of water in 2010 was more important in the southern tropical tributaries of the upper Solimes than in the northern ones

Integrated extraction-adsorption process for selective recovery of antioxidant phenolics from food industry by-product

International audienceThis work aimed at proposing a green process for selective recovery of antioxidant polyphenols, in order to propose a sustainable valorisation of chicory grounds, a food-industry by-product. An integrated extraction-adsorption process was performed, enabling simultaneous extraction of phenolics and their purification in a single operation. After selecting the most efficient adsorbent among tested and experimental conditions for adsorption and desorption of antioxidant polyphenols, the integrated process was studied, using a central composite design, considering total polyphenols yield, antioxidant activity and energy consumption of the equipment. Influence of processing time (2, 4 or 6 h), processing flow rate (1, 3 or 5 L.h(-1)) and resin/chicory grounds ratio (1/10, 2/10 or 3/10, d.w./d.w.) were investigated. A mathematical model for multi-criteria optimisation was proposed. The integrated process enabled to improve polyphenols recovery efficiency by 63% and to reduce energy consumption by 2.8 times, compared to conventional process, where extraction and adsorption were performed successively

Analyse bayésienne des courbes de tarage hauteur-dénivelée-débit et de leurs incertitudes

International audienc

Oxygen transfer in three phase inverse fluidized bed bioreactor during biosurfactant production by Bacillus subtilis.

Production of microbial biosurfactants requires development of bioreactors enabling sufficient oxygen supply and foaming control. Gas–liquid mass transfer in a three-phase inverse fluidized bed reactor designed for biosurfactant production by Bacillus subtilis was studied. The influence of main parameters on kLa was investigated in model and real fermentation conditions. Oxygen transfer increased up to 175% and up to 24% with the increase of superficial gas and liquid velocities, respectively. The oxygen transfer obtained in the TPIFB bioreactor (kLa up to 0.015 s−1) was higher than in the other bioreactors used for biosurfactant production. A significant decrease of kLa (up to 27%) was measured during fermentation process. It was shown that this decrease of kLa was a result of surface tension decrease due to the production of biosurfactants. However the oxygen transfer remained important and allowed a correct oxygen supply for the aerobic B. subtilis strains. A correlation based on dimensional analysis was proposed to estimate kLa in function of the influencing parameters, integrating surface tension effects. This correlation allowed estimating correctly kLa in the presence or not of solid particles. The correlation being based on dimensionless numbers, it could help for further process control and scale-up considerations

Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River

Formation of mountain ranges results from complex coupling between lithospheric deformation, mechanisms linked to subduction and surface processes: weathering, erosion, and climate. Today, erosion of the eastern Andean cordillera and sub-Andean foothills supplies over 99% of the sediment load passing through the Amazon Basin. Denudation rates in the upper Ucayali basin are rapid, favoured by a marked seasonality in this region and extreme precipitation cells above sedimentary strata, uplifted during Neogene times by a still active sub-Andean tectonic thrust. Around 40% of those sediments are trapped in the Ucayali retro-foreland basin system. Recent advances in remote sensing for Amazonian large rivers now allow us to complete the ground hydrological data. In this work, we propose a first estimation of the erosion and sedimentation budget of the Ucayali River catchment, based on spatial and conventional HYBAM Observatory network

Temporal relations between meander deformation, water discharge and sediment fluxes in the floodplain of the Rio Beni (Bolivian Amazonia)

International audienceThe Andean Cordillera and piedmont significantly influence river system and dynamics, being the source of many of the important rivers of the Amazon basin. The Beni River, whose upper sub-catchments drain the Andean and sub-Andean ranges, is a major tributary of the Madeira River. This study examines the river in the south-western Amazonian lowlands of Bolivia, where it develops mobile meanders. Channel migration, meander-bend morphology and ox-bow lakes are analysed at different temporal and spatial scales. The first part of this study was undertaken with the aim to link the erosion–deposition processes in the active channel with hydrological events. The quantification of annual erosion and deposi- tion areas shows high inter-annual and spatial variability. In this study, we investigate the conditions of sediment exportation in the river in relation to three hydrological parameters (flood intensity, date of discharge peak and duration of the bank-full stage level). The second part of this study, focusing on the abandoned meanders, analyses the cutoff processes and the post-abandonment evolution during 1967–2001. This approach shows the influence of the active channel behaviour on the sediment diffusion and sequestration of the abandoned meanders and allows us to build a first model of the contemporary floodplain evolution