Large rivers are sentinels of climate change. Because of their capacity to drain rainfall over large areas, the waters of these rivers make it possible to measure the effects of global changes but also to understand the impact of human activities that affect their catchment.
Among these basins, the Amazon is exceptional because of its size, the biodiversity it harbors and its influence on the rest of the terrestrial and aquatic ecosystems. The Amazon contributes greatly to the functioning of the Earth system, whether it is by the extent of the surfaces it represents, the volumes of water and materials transported to the ocean, its consumption of CO2 via chemical alteration or its biological production. This river is indeed a major source of water and materials to the oceans and a «natural laboratory» that allows, for example, to evaluate the role of different geomorphological contexts in the export of materials. However, the functioning of the world’s largest river and its biome is now threatened by increasing anthropization (deforestation, mining and energy exploration) and by climate change. The monitoring and understanding of ongoing changes in hydrology as well as in sedimentary, carbon and geochemical flows are fundamental for the Amazonian countries (sustainable use of resources, ecology, transport, contamination…) as well as for the whole world.
The observatory aims to study the hydrology, biogeochemistry and geomorphology on a large scale of some of the largest rivers of the Earth, considered as sentinels of climate change and local land use changes. Mainly focused on the Amazon basin, it also provides data on the Orinoco, Congo, Maroni and Oyapock rivers at their outlet.
The scientific questions concern the understanding of hydroclimatic variability and biogeochemical cycles on the scale of very large river basins (such as the carbon cycle) and the study of sediment transport (landform evolution). The aim is to better understand the impact of human activities (massive changes in land use, deforestation, construction of dams, exploitation of hydrocarbons, etc.) and climate change leading to the acceleration of extreme events (floods, low water periods) on the hydrological functioning and the processes of water-rock interaction, weathering and transfer of materials in the Amazon basin and other large river basins.
Sites and measured variables
The instrumentation allows the collection of hydrological (water levels, flows, ADCP gauges), physico-chemical (temperature, pH, conductivity, etc.) and geochemical (dissolved organic carbon, suspended matter, major and trace elements, rare earths) data in 16 stations. Analyses are carried out at in situ stations (thanks to local observers) or through virtual stations (monitoring of river levels by satellite altimetry, monitoring of sediment load by satellite imagery). Nearly 15,000 data are collected annually on all stations. Measurements using standardized protocols and the analysis of results are carried out in common with the network partners, thus promoting regional and North-South exchanges. HYBAM has 13 sites in the Amazon basin on the Amazon River and its main tributaries (from upstream to downstream: Marañon, Ucayali, Napo, Solimões, Purus, Béni, Madeira, Negro, Branco, Tapajos), 2 in French Guiana (Maroni, Oyapock), and the Congo River.
Partners and further information
The HYBAM observatory is an observation system funded by IRD, INSU and the Midi-Pyrénées Observatory in Toulouse. It operates within a network of partners in the South, including universities, research institutes and technical services, with which it maintains 14 cooperation agreements. In all the areas studied, SNO HYBAM is the only structure providing long-term geochemical monitoring and often the only one to document sedimentary and even liquid flows. This information is critical from a fundamental point of view as well as for the management of the resource. It is shared with all national partners, put online and benefits a large number of studies (> 600 published articles).