Distribution of water depth estimates for the entire Balbina Reservoir area. Inset map shows two regions with contrasting pre-filling topography and post-filling lake
bathymetry on opposite sides of the Uatumã River. We estimated the bathymetry for the entire open-water reservoir area, using post-filling radar images of the study area, by
first excluding a mask including all present-day islands and mainland areas, and then reclassifying all remaining pixels currently corresponding to open-water and attributing
them pixel-scale depth values by matching the highest pixel values to the maximum reservoir depth (30 m), given the mean reservoir water level, which is tightly controlled
at a stable water-level of 50 m at the dam site