These data are the river basin shapefile components of a curated set of historical daily rainfall and streamflow data for a large region spanning the southern Amazonian rainforest and tropical savanna biomes of Brazil.

Basin attributes include: a site ID ("site"); the basin area in square km ("area"); the fraction of the basin area impacted by (draining to) a large (>30MW) reservoir ("resvr"); and a numeric indicator for basins located within the same basin network, i.e. nested basins ("group"). None of these basins have reservoir facilities located at their outlets as of 2013, although they may have reservoirs upstream - as indicated by the basin "resvr" attribute. Basin and reservoir drainage area boundaries were derived from free, publicly-available geographic information systems (GIS) data obtained from the Brazilian water management and electricity regulatory agencies: Agência Nacional de Águas (ANA) and Agência Nacional de Energia Elétrica (ANEEL), respectively.

For each unique basin, there exists a corresponding flow gauge location record (see "Flow gauge locations for the Brazilian rainforest-savanna transition zone") and a flow time series record for discharge at the basin outlet (see "Flow gauge data for the Brazilian rainforest-savanna transition zone"); these are identified by the same site ID numbers.

Additional data package information and contents, including raw data files, documentation of data acquisition and processing, and related programmatic scripts, are available via Figshare: https://doi.org/10.6084/m9.figshare.3100912.v1