Water level dynamics of Amazon wetlands at the watershed scale by satellite altimetry

Abstract

In this study we used satellite altimetry to characterize the time and space variations in water stored in or circulating through rivers, floodplains, wetlands and lakes in the major sub-basins of the Amazon basin. Using a specific methodology to rigorously select original three-dimensional (3D) data from an Environmental Satellite (ENVISAT) mission, water level time series were calculated at the crossing path of the satellite tracks with the water bodies. We took advantage of the continuous sampling of the water level along the satellite track segments that cross the watershed to analyse both spatial and temporal relationships between: (i) the river and its floodplain and (ii) different basins. This work evidences in particular the existence of water leaking between the Negro and Solimões basins at the high water stage. It highlights that the phenomenon of a secondary flood peak occurring in the water level series in the Solimões basin at rising water, known as repiquete, is caused by the rain equatorial regime of the northern upstream tributaries of the Solimões River, but is disconnected from the same phenomenon occurring within the Rio Negro basin.

Acknowledgements

We thank the reviewers who greatly helped in rewriting the preliminary version of the manuscript. We are grateful for the financial support provided to the first author by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil and by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Brazil (ref. CAPES/COFECUB no. 516/05), and to the French contributors funded by the French Centre National d'Etudes Spatiale through the TOSCA programme, project Hydrologie Spatiale. Acquisition of JERS-1 imagery was made possible by NASDA's Global Rain Forest Mapping Project. We thank the Instituto Brasileiro de Geografia e Estatística (IBGE) for the maps of the region, the Agência Nacional de Águas (ANA), Brazil for the gauge data and the CTOH (Centre de Topographie des Océans et de l'Hydrosphère, LEGOS, France) for access to ERS-2 and ENVISAT GDRs and additional tropospheric corrections through their online database system, and the European Space Agency (ESA) for granting the use of the data. We are also grateful to Gerard Cochonneau for his work on the treatment of the altimetric data.