In the Amazon floodplains, hydrological variability plays a crucial role by shaping the habitat, offering shelter and feeding or breeding areas. During the dry season, some fresh water turtles such as the yellow-spotted turtle (Podocnemis unifilis Troschel, 1848) use the sand banks at point bar areas as breeding sites, which must be available in time for the start of oviposition. In this study, we used altimetry-derived water level data from radar satellites combined with in-situ hydrological measurements to evaluate water level variations and relate them to oviposition starting dates (2003-2012) from Pacaya-Samiria National Reserve, Peru. Synchronous hydrological behavior was found between the major river stems (Ucayali and Marañon) and the inner rivers (Pacaya and Samiria), thus enabling the utilization of water level in the main river stem to correlate with oviposition in the inner r...

Study region The upper Amazon River, where the water level measured at the Tamshiyacu station (Peru) shows seasonal variability of seven meters. Study focus Key parameters for the flood recession period (beginning, end and duration of the low-water period, velocity of water falling and rising, and inversions in the direction of stage change known as “repiquete” events) are analyzed for the period 1985–2015, along with their relationship to rainfall integrated in the upper Amazon basin at Tamshiyacu. New hydrological insights the low-water period lasts about four months, beginning, on average, at the end of July and ending in early November. Since the late 1990s, the low-water period has tended to end later, last longer and the flood recession ends more abruptly than it used to. This may be related to the increased frequency of dry days during the austral winter in the central and s...

In this study, we used moderate resolution imaging spectroradiometer (MODIS) satellite images to quantify the sedimentation processes in a cascade of six hydropower dams along a 700-km transect in the Paranapanema River in Brazil. Turbidity field measurement acquired over 10 years were used to calibrate a turbidity retrieval algorithm based on MODIS surface reflectance products. An independent field dataset was used to validate the remote sensing estimates showing fine accuracy (RMSE of 9.5 NTU, r = 0.75, N = 138). By processing 13 years of MODIS images since 2000, we showed that satellite data can provide robust turbidity monitoring over the entire transect and can identify extreme sediment discharge events occurring on daily to annual scales. We retrieved the decrease in the water turbidity as a function of distance within each reservoir that is related to sedimentation processes. The ...

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 ...

La 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 e...

The aim of this study is to evaluate the ability of the ORCHIDEE land surface model to simulate streamflows over each sub-basin of the Amazon River basin. For this purpose, simulations are performed with a routing module including the influence of floodplains and swamps on river discharge and validated against on-site hydrological measurements collected within the HYBAM observatory over the 1980–2000 period. When forced by the NCC global meteorological dataset, the initial version of ORCHIDEE shows discrepancies with ORE HYBAM measurements with underestimation by 15 % of the annual mean streamflow at Obidos hydrological station. Consequently, several improvements are incrementally added to the initial simulation in order to reduce those discrepancies. First, values of NCC precipitation are substituted by ORE HYBAM daily in-situ rainfall observations from the meteorological services of ...

El 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 captació...

El 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...