> this region have been governed by workers party since forever.
Not quite. The state of Rio Grande do Sul had 2 PT (Worker's Party) Governors: Olívio Dutra (1999-2003) and Tarso Genro (2011-2015).
RS's capital city Porto Alegre had a much longer PT administration (Starting with Olívio Dutra in 1989, ending with João Verle in 2005).
> zero floods. well, small ones that overridden the dams
Fine, but there hasn't been this much water, and especially condensed in this small period of a few days, since ... well, I imagine always. Even the previous record flood of 1941 in Porto Alegre was due to 22 days of rain. This took about 3 or 4.
> last extreme right elections put an extreme right government in that region
I'm not sure I'd call Eduardo Leite (current and previous State Governor) extreme right. That said, he's a typical liberal, and as such he likes to defund the State. He decreased public spending in civil protection by 90% from last year. And that's after last year also saw floodings and cyclones.
If you're talking about the Porto Alegre administration, I would maybe agree with the "extreme right" label on the current mayor, Sebastião Melo. Previous right-wing mayors have been mostly regular conservatives and/or regular liberals. Still right, still bad, but not quite Bolsonaro bad (though at least some are Bolsonaro supporters).
---
I came across a document from Porto Alegre's administration in 1992 [0] (first time with the Worker's Party in office, under the always thoughtful and overly intelligent Olívio Dutra) where they do an extensive analysis of the anti-flood systems in place, options on how to improve them and how important participation of civil society is in these processes.
Back then we had the world's first Participatory Budget [1] in place. In the document, the administration acknowledges that sanitation and flood prevention were not among their main flags during the election campaign, but the people voted and the administration started working on it.
This is how democracy should work IMO. It's not perfect but it's way better than simply voting to put people in office. Unfortunately it's been all but dismantled after PT left the administration.
[0] https://www.dropbox.com/scl/fi/y02s8cvxf6qts3ktgc70q/PREVENI...
[1] https://en.wikipedia.org/wiki/Participatory_budgeting