Articles | Volume 7, issue 1
Brief communication
12 Mar 2015
Brief communication |  | 12 Mar 2015

Mapping hydrological environments in central Amazonia: ground validation and surface model based on SRTM DEM data corrected for deforestation

G. M. Moulatlet, C. D. Rennó, F. R. C. Costa, T. Emilio, and J. Schietti

Abstract. One of the most important freely available digital elevation models (DEMs) for Amazonia is the one obtained by the Shuttle Radar Topography Mission (SRTM). However, since SRTM tends to represent the vegetation surface instead of the ground surface, the broad use of SRTM DEM as a framework for terrain description in Amazonia is hampered by the presence of deforested areas. We present here two data sets: (1) a deforestation-corrected SRTM DEM for the interfluve between the Purus and Madeira rivers, in central Amazonia, which passed through a careful identification of different environments and has deforestation features corrected by a new method of increasing pixel values of the DEM (Rennó, 2009); and (2) a set of 18 hydrological-topographic descriptors based on the corrected SRTM DEM. Deforestation features are related with the opening of an 800 km road in the central part of the interfluve and occupancy of its vicinity. We used topographic profiles from the pristine forest to the deforested feature to evaluate the recovery of the original canopy coverage by minimizing canopy height variation (corrections ranged from 1 to 38 m). The hydrological–topographic description was obtained by the Height Above the Nearest Drainage (HAND) algorithm, which normalizes the terrain elevation (above sea level) by the elevation of the nearest hydrologically connected drainage. The validation of the HAND data set was done by in situ hydrological description of 110 km of walking trails also available in this data set. The new SRTM DEM expands the applicability of SRTM data for landscape modelling; the data sets of hydrological features based on topographic modelling are undoubtedly appropriate for ecological modelling and an important contribution to environmental mapping of Amazonia. The deforestation-corrected SRTM DEM is available at; the polygons selected for deforestation correction are available at; the set of hydrological–topographic descriptors is available at; the environmental description of access trails is available at; and the limits of deforestation corrections and drainage validation are available at

Short summary
This work presents two data sets: a digital elevation model in which deforestation effects were minimized over a large area in Central Amazonia and a set of 18 topographic–hydrological descriptors calculated by the use of the Vertical Distance to the Nearest Drainage algorithm (HAND). We describe the methodology to generate and validate the data sets. Moreover, we present a brief discussion about the applicability of the data to fill the gap of environmental data in Amazonian lowland forests.