Browsing by Author "Vauchel, Phillippe"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
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 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.