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 21 to August 19, 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 in Peruvian territory, which was classified as “tending toward very dry.” The Ucayali River basin was classified as “tending toward wet.” The Marañón 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, Jutaí, and Purus rivers, which had positive precipitation anomalies; meanwhile, the Juruá River basin experienced rainfall close to the climatological norm for the period. With positive precipitation anomalies, the Beni River basin was characterized as tending toward extremely rainy conditions; the Mamoré basin as very rainy; the Aripuanã basin as tending toward very rainy; the Ji-Paraná basin as rainy; and the Guaporé basin as tending toward rainy. Meanwhile, the Madeira River basin was characterized as normal. The Negro and Branco river basins continued to experience intense negative precipitation anomalies, and were classified 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 northeastern and northwestern Pará were classified as tending toward extremely dry conditions. On the right bank, the Iriri, Juruena, and Teles Pires river basins recorded positive precipitation anomalies, although the average 30-day accumulated precipitation ranged from 7 to 18 mm; on the other hand, the Abacaxis, Curuá Una, and Tapajós river basins were classified as “tending toward very dry,” very dry, and dry, respectively, with accumulated precipitation between 8 and 15 mm, indicating a shortage of rainfall in this region. The Xingu River basin experienced rainfall close to the climatological average for the period. The main course of the Amazon River within Brazilian territory experienced rainfall well below the climatological average and was categorized as “tending toward extremely 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 drought is already spreading to the right-bank tributaries within Brazilian territory.