Single-line diagram of the basins represented

Analysis of the Single-Line Diagram of the Shown Basins

The analysis of the unifilar diagram shows the distribution and classification of river basins according to the categorization of precipitation anomalies for the period between July 14 to August 12, 2026. In the Andean headwaters, negative precipitation anomalies were concentrated in the Napo River basin, which was classified as “very dry,” and in the main stem of the Amazon River within Peruvian territory, which was classified as “tending toward very dry.” The Ucayali River basin was classified as “tending toward wet.” The Marañon River basin was classified as “normal.” The main course of the Solimões River and the basins of the Coari, Içá, Japurá, and Tefé rivers were characterized as having a precipitation deficit, as they experienced rainfall below climatological norms, in contrast to the basins of the Javari and Jutaí rivers, which showed positive precipitation anomalies, while the Juruá and Purus river basins recorded rainfall close to the climatological average for the period. The Madeira River and its main tributaries recorded rainfall above the climatological average: the Aripuanã River basin was classified as very rainy, the Aripuanã, Beni, and Mamoré river basins as tending toward very rainy, the Juruá River basin as rainy, and the Madeira River basin as tending toward rainy. The Guaporé River was classified as being in normal conditions. The Negro and Branco river basins continued to experience negative precipitation anomalies, being categorized as tending toward extremely dry and extremely dry, respectively. On the left bank of the Amazon River in Brazilian territory, negative precipitation anomalies continued to predominate: the basins in northeastern Amazonas and northwestern Pará were classified as tending toward extremely dry conditions, while those located in northeastern Pará were classified as very dry. On the right bank, the Iriri, Juruena, Teles Pires, and Xingu river basins recorded positive precipitation anomalies; although significant for vegetation, the average 30-day accumulated precipitation ranged from 9 to 39 mm in these basins. In contrast, the Abacaxis and Curuá Una river basins were classified as “tending toward dry” and “dry,” respectively, with accumulated precipitation between 17 and 24 mm, signaling a shortage of rainfall in this region. The Tapajós River basin experienced rainfall close to the climatological average for the period. The main course of the Amazon River within Brazilian territory experienced rainfall below the climatological average, categorized as “tending toward very dry.” Negative precipitation anomalies are spreading from north to south across the basin, indicating intensifying drought conditions in the left-bank tributaries of the Amazon basin - from the mountain range to the river’s mouth near Marajó Island. At this time, the advance of the drought is already evident at the mouths of the right-bank tributaries within Brazilian territory.