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 June 23 to July 22, 2026. In the Andean headwaters (Marañón, Napo, Ucayali, and the main stem of the Amazon), negative precipitation anomalies were concentrated in the Napo River basin and the main stem of the Amazon within Peruvian territory, both of which were classified as “very dry”; the Ucayali River basin was classified as “dry.” The Marañón River basin was classified as normal. The main course of the Solimões River, as well as the Içá, Japurá, and Jutaí river basins, recorded precipitation deficits; the Javari, Juruá, and Purus river basins experienced rainfall close to the climatological average for the period, while the Tefé and Coari river basins recorded precipitation above the climatological average. The Aripuanã, Guaporé, Madeira, and Mamoré river basins showed positive precipitation anomalies; the Beni and Ji-Paraná river basins recorded rainfall close to the climatological average. The Negro and Branco river basins experienced below-average precipitation and were classified as experiencing dry and very dry conditions, respectively. On the left bank of the Amazon River within Brazilian territory, negative precipitation anomalies predominated: the basins in northeastern Amazonas and northeastern Pará were classified as experiencing drought conditions, while those in northwestern Pará were classified as experiencing very dry conditions. On the right bank, the Iriri and Xingu river basins were classified as rainy; the Teles Pires River basin was categorized as tending toward very rainy; and the Juruena River basin was categorized as very rainy. The Curuá Una and Tapajós river basins were near normal, while the Abacaxis River basin was classified as tending toward dry conditions. The main course of the Amazon River within Brazilian territory experienced rainfall close to climatological norms. At this time of year, climatological data indicate 30-day cumulative precipitation of less than 20 mm in the southeastern Amazon basin; therefore, anomalously high precipitation should be interpreted with caution.