The decrease in water volume was seen in the Douro, Mondego, Arade, Mira, Ave and Lima basins and the increase in the Tagus, Guadiana, Sado, Oeste and Cávado basins, indicates the monthly report of the National Water Resources Information System (SNIRH).
The Barlavento Basin remained at the same value at the end of November as it was on the last day of October, 7.6 percent of capacity, and continues to be the one that stores the least water in mainland Portugal.
After Barlavento, the Arade basins, with 24.7 percent, and Mira, with 30.8 percent, are the ones that retain the least water.
With the largest amount of water stored is the Cávado basin, with 88.4 percent, followed by the Ave basin, with 81 percent, and the Douro basin, with 79.5 percent.
The basin that had the greatest accumulated water loss was Ave, which went from 99.6 percent at the end of October to 81 percent at the end of November. The one with the biggest gain was Cávado, going from 83.3 percent to 88.4 percent of capacity.
The monthly storage report for reservoirs in mainland Portugal also states that of the 60 reservoirs monitored, 15 had, on the last day of November, water availability greater than 80% of the total volume and 17 availability below 40 percent.
Each river basin may correspond to more than one reservoir.
The SNIRH report states that last month's storages by river basin are higher than the November average (1990/91 to 2022/23), with the exception of the Mondego, Sado, Guadiana, Mira, Ribeiras do Algarve and Arade basins.