PORTO ALEGRE, Brazil — Vanderson Chaves has faced many challenges in more than a decade as a Paralympic fencer, but none as fearsome as the massive floods in Brazil’s Rio Grande do Sul state.

The waters washed away his equipment, dozens of medals, his passport — and might have even thwarted his chances of reaching the Paris Games in September.

Chaves’ ground-floor apartment, ideal for his wheelchair, lies in an elevated area of state capital Porto Alegre. Still, that didn’t spare him…