Specific yield discharge and mean precipitation in São Francisco Basin

The São Francisco River drains an area of 640,000 km² and is responsible for the sustainability of the 503 municipalities in the basin where 14 million people live. This study was undertaken to investigate the mean precipitation and the specific yield discharge in the São Francisco Basin. The analysis was made considering 178 rain-gauge stations and 77 stations to measure stream flow. The specific yield discharge was obtained by dividing the mean annual discharge by the drainage area upstream from the station, and the mean precipitation in the upstream area from each station was obtained by the Thiessen polygon method. The results indicated that the mean precipitation decreased from the Upper São Francisco to Lower São Francisco, and the specific yield discharge decreases along the river, the maximum specific discharge was 22.6 L s-1 km-2, in Iguatama, the first station in the river, and the lowest stream flow was 4.2 L s-1 km-2, in Traipu, the last station in the São Francisco river.

hydrological behavior; water availability; water resources