Browsing by Author "Guyot, Jean Loup"
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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 Climate variability and extreme drought in the upper Solimões River (western Amazon Basin): understanding the exceptional 2010 drought(American Geophysical Union (AGU), 2011-07) Espinoza, Jhan Carlo; Ronchail, Josyane; Guyot, Jean Loup; Junquas, Clémentine; Vauchel, Philippe; Lavado, Waldo; Drapeau, Guillaume; Pombosa, RodrigoThis 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 Solimões 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 Solimões, 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 Niño 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 Solimões. Its intensity and its length, when compared to the 2005 drought, can be explained by the addition of an El Niño 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 Solimões than in the northern ones.Item Restricted Contrasting regional discharge evolutions in the Amazon basin (1974–2004)(Elsevier, 2009-09-15) Espinoza, Jhan Carlo; Guyot, Jean Loup; Ronchail, Josyane; Cochonneau, Gérard; Filizola, Naziano; Fraizy, Pascal; Labat, David; Oliveira, Eurides de; Ordoñez, Juan Julio; Vauchel, PhillippeFormer hydrological studies in the Amazon Basin generally describe annual discharge variability on the main stem. However, the downstream Amazon River only represents the mean state of the Amazonian hydrological system. This study therefore uses a new data set including daily discharge in 18 sub-basins to analyze the variability of regional extremes in the Amazon basin, after recalling the diversity of the hydrological annual cycles within the Amazon basin. Several statistical tests are applied in order to detect trends and breaks in the time series. We show that during the 1974–2004 period, the stability of the mean discharge on the main stem in Óbidos is explained by opposite regional features that principally involve Andean rivers: a decrease in the low stage runoff, particularly important in the southern regions, and an increase in the high stage runoff in the northwestern region. Both features are observed from the beginning of the nineties. These features are also observed in smaller meridian sub-basins in Peru and Bolivia. Moreover we show that the changes in discharge extremes are related to the regional pluriannual rainfall variability and the associated atmospheric circulation as well as to tropical large-scale climatic indicators.Item Open Access Global karst springs hydrograph dataset for research and management of the world’s fastest-flowing groundwater(Nature Research, 2020-02) Olarinoye, Tunde; Gleeson, Tom; Marx, Vera; Seeger, Stefan; Adinehvand, Rouhollah; Allocca, Vincenzo; Andreo, Bartolome; Apaéstegui Campos, James Emiliano; Apolit, Christophe; Arfib, Bruno; Auler, Augusto; Barberá, Juan Antonio; Batiot-Guilhe, Christelle; Bechtel, Timothy; Binet, Stephane; Bittner, Daniel; Blatnik, Matej; Bolger, Terry; Brunet, Pascal; Jean-Baptiste, Charlier; Chen, Zhao; Chiogna, Gabriele; Coxon, Gemma; De Vita, Pantaleone; Doummar, Joanna; Epting, Jannis; Fournier, Matthieu; Goldscheider, Nico; Gunn, John; Guo, Fang; Guyot, Jean Loup; Howden, Nicholas; Huggenberger, Peter; Hunt, Brian; Jeannin, Pierre-Yves; Jiang, Guanghui; Jones, Greg; Jourde, Herve; Karmann, Ivo; Koit, Oliver; Kordilla, Jannes; Labat, David; Ladouche, Bernard; Serena Liso, Isabella; Liu, Zaihua; Massei, Nicolas; Mazzilli, Naomi; Mudarra, Matías; Parise, Mario; Pu, Junbing; Ravbar, Nataša; Hidalgo Sanchez, Liz; Santo, Antonio; Sauter, Martin; Sivelle, Vianney; Skoglund, Rannveig Øvrevik; Stevanovic, Zoran; Wood, Cameron; Worthington, Stephen; Hartmann, AndreasKarst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations.Item Open Access Influencia de la precipitación sobre los flujos de sedimentos en el Amazonas: una síntesis basada en 20 años de monitoreo(Instituto Geofísico del Perú, 2020-04) Armijos Cardenas, Elisa Natalia; Crave, Alain; Espinoza, Jhan Carlo; Filizola, Naziano; Espinoza-Villar, Raúl; Ayes, Irma; Fonseca, Paula; Fraizy, Pascal; Gutierrez, Omar; Vauchel, Philippe; Camenen, Benoit; Martiınez, Jean Michel; Dos Santos, André; Santini, William; Cochonneau, Gérard; Guyot, Jean LoupLa vida en la región amazónica está principalmente relacionada con la estacionalidad del régimen hidrológico fluvial. La riqueza de la biodiversidad y productividad de la llanura de inundación depende de los nutrientes y la materia orgánica que son transportados por los ríos en los sedimentos en suspensión, desde los Andes hacia el océano Atlántico. Sin embargo, poco se conoce sobre la influencia de la variabilidad hidrológica y pluvial en los flujos sedimentarios. Para abordar esta brecha, analizamos 3069 muestras superficiales de agua y sedimentos recolectadas en el centro del río, cada 10 días durante el período 1995-2014, en 6 estaciones ubicadas en el río Amazonas y sus tributarios. Este análisis se ha realizado haciendo una distinción del tamaño de las partículas, sedimentos finos (arcilla y limo) y sedimentos gruesos (arena). Considerando esta distinción, se estimó, por primera vez, que en la llanura amazónica predomina el flujo de sedimento fino con un 60 % y las arenas representan el 40 % complementario. La lluvia tiene una relación con la producción de sedimentos finos, mientras que el caudal rige el transporte de arenas en suspensión. Adicionalmente, este trabajo presenta el tiempo de respuesta entre la lluvia y el caudal. Los resultados obtenidos en este estudio son una contribución importante a la dinámica biológica y geomorfológica en la cuenca del Amazonas.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 Restricted Precipitation changes over the eastern Bolivian Andes inferred from speleothem (δ¹⁸O) records for the last 1400 years(Elsevier, 2018-07-15) Apaéstegui Campos, James Emiliano; William Cruz, Francisco; Vuille, Mathias; Fohlmeister, Jens; Espinoza, Jhan Carlo; Sifeddine, Abdelfettah; Strikis, Nicolas; Guyot, Jean Loup; Ventura, Roberto; Cheng, Hai; Edwards, R. LawrenceHere we present high-resolution δ¹⁸ records obtained from speleothems collected in the eastern Bolivian Andes. The stable isotope records are related to the regional- to large-scale atmospheric circulation over South America and allow interpreting changes in δ¹⁸ during the last 1400 yr as a function of changes in precipitation regimes over the southern tropical Andes. Two distinct phases with more negative δ¹⁸ values, interpreted as periods of increased convective activity over the eastern Andean Cordillera in Bolivia are observed concomitantly with periods of global climate anomalies during the last millennium, such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) respectively. Changes in the Bolivian δ¹⁸ record during the LIA are apparently related to a southward displacement of the Intertropical Convergence Zone (ITCZ), which acts as a main moisture driver to intensify convection over the tropical continent. During the MCA, however, the increased convective activity observed in the Bolivian record is likely the result of a different mechanism, which implies moisture sourced mainly from the southern tropical Atlantic. This interpretation is consistent with paleoclimate records further to the north in the tropical Andes that show progressively drier conditions during this time period, indicating a more northerly position of the ITCZ. The transition period between the MCA and the LIA shows a slight tendency toward increased δ¹⁸ values, indicating weakened convective activity. Our results also reveal a non-stationary anti-phased behavior between the δ¹⁸ reconstructions from Bolivia and northeastern Brazil that confirms a continental-scale east–west teleconnection across South America during the LIA.Item Restricted Spatio‐temporal rainfall variability in the Amazon basin countries (Brazil, Peru, Bolivia, Colombia, and Ecuador)(Royal Meteorological Society, 2008-09) Espinoza, Jhan Carlo; Ronchail, Josyane; Guyot, Jean Loup; Cochonneau, Gerard; Naziano, Filizola; Lavado, Waldo; De Oliveira, Eurides; Pombosa, Rodrigo; Vauchel, PhilippeRainfall variability in the Amazon basin (AB) is analysed for the 1964–2003 period. It is based on 756 pluviometric stations distributed throughout the AB countries. For the first time it includes data from Bolivia, Peru, Ecuador, and Colombia. In particular, the recent availability of rainfall data from the Andean countries makes it possible to complete previous studies. The impact of mountain ranges on rainfall is pointed out. The highest rainfall in the AB is observed in low windward regions, and low rainfall is measured in leeward and elevated stations. Additionally, rainfall regimes are more diversified in the Andean regions than in the lowlands. Rainfall spatio‐temporal variability is studied based on a varimax‐rotated principal component analysis (PCA). Long‐term variability with a decreasing rainfall since the 1980s prevails in June–July–August (JJA) and September October–November (SON). During the rainiest seasons, i.e. December–January–February (DJF) and March–April–May (MAM), the main variability is at decadal and interannual time scales. Interdecadal variability is related to long‐term changes in the Pacific Ocean, whereas decadal variability, opposing the northwest and the south of the AB, is associated with changes in the strength of the low‐level jet (LLJ) along the Andes. Interannual variability characterizes more specifically the northeast of the basin and the southern tropical Andes. It is related to El Niño‐Southern Oscillation (ENSO) and to the sea surface temperature (SST) gradient over the tropical Atlantic. Mean rainfall in the basin decreases during the 1975–2003 period at an annual rate estimated to be − 0.32%. Break tests show that this decrease has been particularly important since 1982. Further insights into this phenomenon will permit to identify the impact of climate on the hydrology of the AB. Copyright © 2008 Royal Meteorological Society.Item Open Access The extreme 2014 flood in south-western Amazon basin: the role of tropical-subtropical South Atlantic SST gradient(IOP Publishing, 2014-12-08) Espinoza, Jhan Carlo; Marengo, José Antonio; Ronchail, Josyane; Molina Carpio, Jorge; Noriega Flores, Luis; Guyot, Jean LoupUnprecedented wet conditions are reported in the 2014 summer (December–March) in Southwestern Amazon, with rainfall about 100% above normal. Discharge in the Madeira River (the main southern Amazon tributary) has been 74% higher than normal (58 000 m³ s⁻¹) at Porto Velho and 380% (25 000 m³ s⁻¹) at Rurrenabaque, at the exit of the Andes in summer, while levels of the Rio Negro at Manaus were 29.47 m in June 2014, corresponding to the fifth highest record during the 113 years record of the Rio Negro. While previous floods in Amazonia have been related to La Niña and/or warmer than normal tropical South Atlantic, the 2014 rainfall and flood anomalies are associated with warm condition in the western Pacific-Indian Ocean and with an exceptionally warm Subtropical South Atlantic. Our results suggest that the tropical and subtropical South Atlantic SST gradient is a main driver for moisture transport from the Atlantic toward southwestern Amazon, and this became exceptionally intense during summer of 2014.Item Restricted The major floods in the Amazonas River and tributaries (Western Amazon Basin) during the 1970-2012 period: a focus on the 2012 flood(American Meteorological Society, 2013-06) Espinoza, Jhan Carlo; Ronchail, Josyane; Frappart, Frédéric; Lavado, Waldo; Santini, William; Guyot, Jean LoupIn this work, the authors analyze the origin of the extreme floods in the Peruvian Amazonas River during the 1970-2012 period, focusing on the recent April 2012 flooding (55 400 m(³) s(⁻¹)). Several hydrological variables, such as rainfall, terrestrial water storage, and discharge, point out that the unprecedented 2012 flood is mainly related to an early and abundant wet season over the north of the basin. Thus, the peak of the Maranon River, the northern contributor of the Amazonas, occurred sooner than usual (in April instead of May), coinciding with the peak of the Ucayali River, the southern contributor. This concomitance caused a dramatic flood downstream in the Peruvian Amazonas. These results are compared to the amplitude and timing of the three most severe extreme floods (1970-2011). The analysis of the climatic features related to the most important floods (1986, 1993, 1999, and 2012) suggests that they are characterized by a La Nina event, which originates a geopotential height wave train near the ground, with positive anomalies over the subtropical South and North Pacific and Atlantic and over southeastern South America. These patterns contribute to 1) the origin of an abundant humidity transport flux from the tropical North Atlantic and the Caribbean Sea toward the northwestern Amazon and 2) the maintenance of the monsoon flux over this region. They both favor a strong convergence of humidity in the northern Amazonas basin. Finally, the authors suggest that the intensity of floods is more likely related to an early La Nina event (as observed during the 2011/12 season), early rainfall, and simultaneous peaks of both tributaries of the Amazonas River.Item Restricted Trends in rainfall and temperature in the Peruvian Amazon–Andes basin over the last 40 years (1965–2007)(Wiley, 2013-09-30) Lavado Casimiro, Waldo Sven; Labat, David; Ronchail, Josyane; Espinoza, Jhan Carlo; Guyot, Jean LoupThe hydroclimatology of the Peruvian Amazon-Andes basin (PAB) which surface corresponds to 7 % of the Amazon basin is still poorly documented. We propose here an extended and original analysis of the temporal evolution of monthly rainfall, mean temperature (Tmean), maximum temperature (Tmax), and minimum temperature (Tmin) time series over two Peruvian Amazon-Andes basins (Huallaga and Ucayali) over the last forty years. This analysis is based on a new and more complete database that includes 77 weather stations over the 1965-2007 period and we focus our attention on both annual and seasonal meteorological time series. A positive significant trend in mean temperature of 0.09°C per decade is detected over the region with similar values in the Andes and Rainforest when considering average data. Though, a high percentage of stations with significant Tmean positive trends are located over the Andes region. Finally, changes in the mean values occurred earlier in Tmax (during the 1970s) than in Tmin (during the 1980s). In the PAB, there is neither trend nor mean-change in rainfall, during the 1965-2007 period. However, annual, summer and autumn rainfall in the southern Andes presents an important interannual variability that is associated with the sea surface temperature (SST) in the tropical Atlantic Ocean while there are limited relationships between rainfall and ENSO events. On the contrary, the interannual temperature variability is mainly related to ENSO events.Item Restricted Uncertainty in suspended sediment load estimates for mountain rivers: case of study of Central Andes in Perú(American Society of Civil Engineers (ASCE), 2013) Morera Julca, Sergio Byron; Mejia-Marcacuzco, Abel; Guyot, Jean Loup; Gálvez, Carlos; Salinas, Francisco; Collas, Manuel; Ingol-Blanco, EusebioThis study evaluates the uncertainty in the estimation of annual and monthly sediment flows in four mountain basins of the Pacific Ocean in Peru. For this end, samples at different time scales (hourly, daily, and monthly) were recorded. The database was broken down into a numerical base to simulate several sampling frequencies. From these timing frequencies, the annual and monthly flow was computed. Likewise, we compare the observed and simulated data, calculating the degree of uncertainty using statistical tests. The results for the 25 and 75 percentiles show that there is a high temporal variability in these Andean watersheds, whose strategy of measurement of solid flows can vary from 6 to 12 days underestimating ~ 20% annually. While for estimating suspended sediment yield (SY) to a monthly time step in the rainy season (December to May), a sampling frequency between 1-5 days which would lead to a maximum error of ± 40% is needed. However, for the dry season (June to September), the sampling can be done one time per month for an error of ± 45% which is less than 2 % in an annual balance. Finally, the results show that the sampling frequency values mentioned above should be reduced to half, for exceptional events (rainy season) where the annual error estimate is around 300%.