The objective of this study was to analyze the susceptibility to flooding in the Forqueta River Basin, RS, Brazil, which suffered a great flood in 2010. For this purpose, an adapted approach was presented for areas with low data availability, integrating hydrological models and geotechnologies. The definition of extreme rainfall in return periods (RP) of 10, 30 and 100 years was carried out by using an intensity-duration-frequency equation. Shuttle Radar Topography Mission data were used to the delimitation of the basins and rivers. The Soil Conservation Service method was used for the transformation of rain runoff, while the spread of river flood wave was conducted by Muskingum-Cunge model. Hydrological simulation revealed that the maximum flow rates can exceed 8,000m3.s-1 at the Forqueta river outfall, with wet area section larger than 5,000m2 and waters rising more than 10m on the average. About 2% of the basin showed some degree of susceptibility, adding up to 53km2 of wetlands. It is concluded that a revision is necessary in the legislation of the municipalities bordering the study area, aiming to redefine the areas susceptible to flooding, considering a zoning with variable flood quotas according to the section of the river.
