The Taquari and Caí rivers reached their flood peak on Tuesday (22) in the valleys of Rio Grande do Sul, Brazil's southernmost state, and the surge is now flowing into the Guaíba, the broad waterway that runs past the state capital, Porto Alegre, where it pushed past the 2-meter mark on the first night of spring. According to MetSul Meteorologia, a private weather firm, the Taquari stabilized at 24.3 meters in Lajeado on Tuesday afternoon, while the Caí peaked at 14.3 meters overnight in São Sebastião do Caí, more than 4 meters above flood stage. MetSul projects the Guaíba will keep rising between Wednesday (23) and Friday (25), peaking between 2.35 and 2.55 meters.
The storm that crossed the state between Sunday (20) and Monday (21) left four people dead and 3,145 out of their homes, according to state Civil Defense figures compiled by Brasil de Fato. The survey counts 527,669 people affected in 137 municipalities with human or material damage, plus 21 houses destroyed and 1,978 that lost their roofs. Firefighters recovered in Caxias do Sul the bodies of a 4-year-old boy swept away inside a car by flash flood, and of a man dragged by the water as he tried to clear a storm drain; the search continues for the boy's mother, 43. The fourth death was a motorcyclist who hit a fallen wire in Pelotas.
Alert in the capital
Porto Alegre's Civil Defense issued a high-risk alert for a possible rise of the Guaíba, in effect from 8 a.m. Wednesday (23) to 10 a.m. Friday (25), Sul 21 reported. Streets on the city's islands begin to flood when the river reaches 2.00 to 2.10 meters, and the gauge at the Mauá pier, the official measuring point for 150 years, read 2.02 meters early on Tuesday night. The flood quota widely known at that point is 3.00 meters; the electronic gauge was the only monitoring station that stayed online during the 2024 flood disaster, when the Brazilian Geological Service calculated the official maximum. MetSul assesses there is no risk for the non-insular part of the city.
On the statewide map, the Civil Defense keeps a very high risk alert for Caí flooding in Montenegro through Wednesday afternoon, even as the river recedes downstream in São Sebastião do Caí, and it records flood thresholds at Nova Palmira on the Caí and at Igrejinha on the Paranhana. The forecast points to risks on the Jacuí, between Dona Francisca and Cachoeira do Sul, the Taquari from Santa Tereza, the Caí from Nova Palmira in Caxias do Sul, and the Sinos at Campo Bom. The rise followed rainfall of up to 200 mm on Monday in the Serra and Campos de Cima da Serra highlands. Five rivers form the Guaíba (Jacuí, Taquari, Caí, Sinos and Gravataí), and because it rained in every basin, all of them are feeding the rise.
A spring under El Niño
For the months ahead, the concern shifts scale: MetSul projects above-average rainfall and more frequent storms this spring, linked to an El Niño that the firm says is heading to an extreme level never seen before, with the possibility of new flood episodes in the state, especially in the second half of the season. In the short term the forecast is settled, with a cold air mass keeping sunshine through Friday (25), which should help the rivers fall. The federal government announced the release of 64 million reais to soften the effects of El Niño, according to GZH, which also reported the opening on Tuesday of a 2,600-square-meter square in Porto Alegre's Quarto Distrito, designed with drainage and tree cover to absorb rain. Civil Defense advises residents to avoid flood-prone areas and to call 190 or 193 in emergencies.