In 2015, an emergency state was declared in Bolivia when Poopó Lake dried up. Climate variability and the increasing need for water are potential factors responsible for this situation. Because field data are missing over the region, no statements are possible about the influence of mentioned factors. This study is a preliminary step toward the understanding of Poopó Lake drought using remote sensing data. First, atmospheric corrections for Landsat (FLAASH and L8SR), seven satellite derived indexes for extracting water bodies, MOD16 evapotranspiration, PERSIANN-CDR and MSWEP rainfall products potentiality were assessed. Then, the fluctuations of Poopó Lake extent over the last 26 years are presented for the first time jointly, with the mean regional annual rainfall. Three main droughts are highlighted between 1990 and 2015: two are associated with negative annual rainfall anomalies in 1994 and 1995 and one associated with positive annual rainfall anomaly in 2015. This suggests that other factors than rainfall influenced the recent disappearance of the lake. The regional evapotranspiration increased by 12.8% between 2000 and 2014. Evapotranspiration increase is not homogeneous over the watershed but limited over the main agriculture regions. Agriculture activity is one of the major factors contributing to the regional desertification and recent disappearance of Poopó Lake.

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 occurred, indicating that a lower peak FSC cannot be explained by changes in the peak discharge months. However, lower FSCs are associated with a downward break in the overall time series registered at the outlet of the major sediment supplier—the Beni River—during 2010.

INFLUENCIA DE LOS CAMBIOS CLIMÁTICOS EN LA ACUMULACIÓN DE CARBONO EN BOFEDALES ALTOANDINOS DURANTE LOS ÚLTIMOS 2 500 AÑ0S

Se diseñó una metodología para identificar y cuantificar la extensión de los bofedales de puna de la cabecera de cuenca del río Chillón, ubicados sobre los 3800 msnm y se eligió un bofedal piloto. Se procesó información de los sensores Landsat TM, ETM+ y OLI de los años 1986 al 2015, una imagen por año. Las imágenes correspondían a la fecha más próxima posible de la misma estación del año. Se generaron mapas de distribución espacial de los índices de vegetación de diferencia normalizada (NDVI), índice de agua de diferencia normalizada (NDWI) y Diferencia Normalizada Índice de Infrarrojos (NDII). Estos índices fueron visualizados en las bandas de Rojo, Verde y Azul (RGB) de la siguiente manera: R (NDII), G (NDVI), B (NDWI). Posteriormente, para zonificar los bofedales, se realizó una clasificación por paralelepípedos sobre esta visualización en RGB. También se utilizó un mapa de pendientes, y con él se generó el mapa de distribución espacial de bofedales, también se obtuvo el vector de bofedales.