Browsing by Author "Baby, Patrice"
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Item Restricted A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme(Elsevier, 2017-10) Vauchel, Phillippe; Santini, William; Guyot, Jean Loup; Moquet, Jean Sébastien; Martínez, Jean Michel; Espinoza, Jhan Carlo; Baby, Patrice; Fuertes, Oscar; Noriega, Luis; Puita, Oscar; Sondag, Francis; Fraizy, Pascal; Armijos Cardenas, Elisa Natalia; Cochonneau, Gérard; Timouk, Franck; Olivera, Eurides de; Filizola, Naziano; Molina, Jorge; Ronchail, JosyaneThe Madeira River is the second largest tributary of the Amazon River. It contributes approximately 13% of the Amazon River flow and it may contribute up to 50% of its sediment discharge to the Atlantic Ocean. Until now, the suspended sediment load of the Madeira River was not well known and was estimated in a broad range from 240 to 715 Mt yr⁻¹. Since 2002, the HYBAM international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents. It is based on the continuous monitoring of a set of 11 gauging stations in the Madeira River watershed from the Andes piedmont to the confluence with the Amazon River, and discrete sampling of the suspended sediment concentration every 7 or 10 days. This paper presents the results of the suspended sediment data obtained in the Madeira drainage basin during 2002–2011. The Madeira River suspended sediment load is estimated at 430 Mt yr⁻¹ near its confluence with the Amazon River. The average production of the Madeira River Andean catchment is estimated at 640 Mt yr⁻¹ (±30%), the corresponding sediment yield for the Andes is estimated at 3000 t km⁻² yr⁻¹ (±30%), and the average denudation rate is estimated at 1.20 mm yr⁻¹ (±30%). Contrary to previous results that had mentioned high sedimentation rates in the Beni River floodplain, we detected no measurable sedimentation process in this part of the basin. On the Mamoré River basin, we observed heavy sediment deposition of approximately 210 Mt yr⁻¹ that seem to confirm previous studies. But while these studies mentioned heavy sedimentation in the floodplain, we showed that sediment deposition occurred mainly in the Andean piedmont and immediate foreland in rivers (Parapeti, Grande, Pirai, Yapacani, Chimoré, Chaparé, Secure, Maniqui) with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands.Item Restricted First record of OSL‐dated fluvial sands in a tropical Andean cave reveals rapid late Quaternary tectonic uplift(Wiley, 2021-06) Baby, Patrice; Viveen, Willem; Sanjurjo‐Sanchez, Jorge; Bigot, Jean‐Yves; Dosseto, Antony; Villegas Lanza, Juan Carlos; Apaéstegui Campos, James Emiliano; Guyot, Jean‐LoupWe present the first results of OSL‐dated fluvial sands extracted from a riverside cave in the tropical Andes. The excellent agreement between the ages of the various samples allowed the calculation of a late Quaternary valley incision rate forced by ongoing uplift of an active Subandean fault‐propagation fold in NE Peru. A structural cross‐section was constructed to understand the relationship between the geometry of the fault‐propagation fold, historical damaging earthquakes and the cave system. The calculated uplift rate is 2.3 to 2.6 mm a⁻¹ over the past 70 ka and can be directly linked to active propagation of west‐verging basement thrusts. It is similar to uplift rates calculated from fluvial terraces in the Subandes of Colombia and Venezuela. The results will help to better assess the seismic hazard and confirm that OSL dating of fluvial sands in caves is a powerful tool to quantify uplift rates of active mountain fronts.Item Open Access Las resurgencias del Alto Mayo (San Martin, Perú): estudio hidrológico sobre un karst tropical andino-amazónico(Sociedad Geológica del Perú, 2018) Grandjouan, Olivier; Hidalgo, Liz; Apaéstegui Campos, James Emiliano; Baby, Patrice; Cochonneau, Gérard; Condori, Elmer; Espinoza, Jhan Carlo; Fraizy, Pascal; Huaman, Darwin; Jourde, Hervé; Mazzilli, Naomi; Morera Julca, Sergio Byron; Peña, Fluquer; Renou, Fabien; Robert, Xavier; Santini, William; Sifeddine, Abdel; Guyot, Jean LoupEl macizo kárstico del Alto Mayo (San Martin, Perú) tiene una red de drenaje desarrollada, activa y poco estudiada. El propósito de este estudio es determinar los caudales de las resurgencias y sus cuencas hidrográficas correspondientes. Los datos hidrológicos y pluviométricos utilizados provienen de los observatorios locales (ANA y SENAMHI) y del proyecto KarstAm. Los caudales medidos alcanzan hasta 24 m³/s en promedio para algunas resurgencias, situándolas entre las más grandes de Sur América. La poca variabilidad temporal del caudal de uno de los acuíferos (Río Negro) muestra un comportamiento atípico en relación a los acuíferos kársticos, pareciéndose más a un acuífero poroso. Los caudales específicos de las cuencas topográficas son superiores a la tendencia regional, por lo que las cuencas hidrográficas han sido recalculadas suponiendo la presencia de captación kárstica. Los datos de precipitación han sido corregidos con el método del vector regional. Los caudales específicos recalculados son más cercanos a los valores regionales, aunque se mantienen con elevados coeficientes de escurrimiento. Estos errores son atribuidos a una subestimación general de las precipitaciones en la cuenca del Alto Mayo.Item Open Access Sediment budget in the Ucayali river basin, an Andean tributary of the Amazon river(Copernicus Publications, 2015-03-03) Santini, William; Martínez, Jean-Michel; Espinoza Villar, Raúl Arnaldo; Cochonneau, Gerard; Vauchel, Philippe; Moquet, Jean Sébastien; Baby, Patrice; Espinoza, Jhan Carlo; Lavado, Waldo; Carranza, Jorge; Guyot, Jean-LoupFormation 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.