El estudio de Molina-Carpio et al. (2023) tuvo como objetivo identificar regiones de lluvia homogéneas dentro de la cuenca alta del río Madeira (Bolivia, Perú y Brasil), que abarca 975.000 km2 y tiene un rango de elevación de 50 a 6450 m s. n. m. Para ello, se usaron series mensuales de 146 estaciones terrestres de los 3 países. Sin imponer restricciones espaciales, el análisis de Agrupamiento Jerárquico (AJ) y el Análisis de Componentes Principales (ACP) agruparon de manera óptima 146 estaciones (1980-2016) en 10 regiones homogéneas distribuidas a lo largo de los Andes y la llanura amazónica. Luego, al aplicar el ACP a las series de lluvias estacionales y vincular los componentes principales con la temperatura de la superficie del mar e índices oceánicos, se obtuvo una perspectiva de los principales moduladores a gran escala de la variabilidad espacio-temporal de las lluvia...

The impact of climate change on droughts in the Lake Titicaca, Desaguadero River, and Lake Poopo basins (TDPS system) within the Altiplano region was evaluated by comparing projected 2034–2064 and observed 1984–2014 hydroclimate time series. The study used bias-corrected monthly climate projections from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), under the Representative Concentration Pathway 8.5 (RCP8.5) emission scenarios. Meteorological, agricultural, and hydrological droughts were analyzed from the standardized precipitation, standardized soil moisture, and standardized runoff indices, respectively, the latter two estimated from a hydrological model. Under scenarios of mean temperature increases up to 3 °C and spatially diverse precipitation changes, our results indicate that meteorological, agricultural, and hydrological droughts will become more inten...

El presente trabajo evalúa el impacto del cambio climático en la ocurrencia de sequías para las cuencas del Lago Titicaca, Río Desaguadero y Lago Poopo (Sistema TDPS). Para tal objetivo, se comparan los resultados de los modelos climáticos para el periodo 1984-2014 con los datos observados y se evalúan las proyecciones en el periodo 2034- 2064. El estudio utilizó proyecciones climáticas mensuales provenientes del proyecto CMIP5 bajo el escenario de emisión RCP8.5. Se corrigió el sesgo y se analizaron las sequías meteorológicas, agrícolas e hidrológicas a partir de los índices estandarizados de precipitación, humedad del suelo y escorrentía, respectivamente. La humedad del suelo y escorrentía fueron estimados a partir del modelo hidrológico GR2M. Ante el aumento de la temperatura regional media de hasta 3 °C y los cambios de intensidad, cantidad y patrón espacial de l...

Unprecedented 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...

The 2022-23 hydrological year in the Lake Titicaca, Desaguadero River, and Lake Poopó hydrological system (TDPS) over the South American Altiplano constituted a historically dry period. This drought was particularly severe during the pre-wet season (October–December), when the TDPS and the adjacent Andean-Amazon region experienced as much as 60% reductions in rainfall. Consequently, Titicaca Lake water levels decreased by 0.05 m from December to January, which is part of the rising lake level period of normal conditions. Such conditions have not been seen since the El Niño-related drought of 1982-83. Using a set of hydroclimatic, Sea Surface Temperature (SST) and atmospheric reanalysis datasets, we find that this new historical drought was associated with enhanced southerly moisture flux anomalies, reducing the inflow of moisture-laden winds from the Amazon basin to the TDPS. Such an...

Fluvial sediment dynamics plays a key role in the Amazonian environment, with most of the sediments originating in the Andes. The Madeira River, the second largest tributary of the Amazon River, contributes up to 50% of its sediment discharge to the Atlantic Ocean, most of it provided by the Andean part of the Madeira basin, in particular the Beni River. In this study, we assessed the rainfall (R)-surface suspended sediment concentration (SSSC) and discharge (Q)-SSSC relationship at the Rurrenabaque station (200 m a.s.l.) in the Beni Andean piedmont (Bolivia). We started by showing how the R and Q relationship varies throughout the hydrological year (September to August), describing a counter-clockwise hysteresis, and went on to evaluate the R–SSSC and Q–SSSC relationships. Although no marked hysteresis is observed in the first case, a clockwise hysteresis is described in the second....

The Madeira River is the second largest Amazon tributary, contributing up to 50% of the Amazon River’s sediment load. The Madeira has significant hydropower potential, which has started to be used by the Madeira Hydroelectric Complex (MHC), with two large dams along the middle stretch of the river. In this study, fine suspended sediment concentration (FSC) data were assessed downstream of the MHC at the Porto Velho gauging station and at the outlet of each tributary (Beni and Mamoré Rivers, upstream from the MHC), from 2003 to 2017. When comparing the pre-MHC (2003–2008) and post-MHC (2015–2017) periods, a 36% decrease in FSC was observed in the Beni River during the peak months of sediment load (December–March). At Porto Velho, a reduction of 30% was found, which responds to the Upper Madeira Basin and hydroelectric regulation. Concerning water discharge, no significant change ...