Gabions Dam for Flood Control, Concórdia, Santa Catarina, Brazil

Concórdia city localized in the east of Santa Catarina state has the main river called “Rio dos Queimados”, this river crosses the urban perimeter. The Rio dos Queimados watershed is characterized by several slopes, and the Concórdia city has been constructed in that irregular ground near of the river and of the several slopes. The river has a great flow capacity, but with the human development and without an occupation plan, a lot of constructions was built on the river with some obstructions that created, along the years, retentions for the flow in different points of the city, and those retentions has generated the flood problem. The MPD Consultant has developed a design to improve 300% the river Queimados capacity, that project was done to increase the river width (5,20m to 8,50m) and to construct a Dam upstream of the city with the detention function. The dam was designed with the Gabion solution, because in the region there were big quantities of stones and few quantities of soil. The Dam has 15m of height, almost 150m of length, and can accumulate more than 260.000m³ of water. To control the flow were installed 3 steel pipes in the dam bottom. For the Dam security was designed and built a spillway with the Gabion coated by concrete, that spillway had the capacity about 1.000 m³/s of flow. Downstream of the dam was built a basin of dissipation with geotextile and stones, that basin has the function to dissipate the energy of the steel pipe flow, and to dissipate the energy created by the fall water of the spillway in a big return time. The gabions applied in the dam are permeable, and to ensure the impermeability, was necessary to compact a small soil quantity behind the Dam. Nowadays the Dam is working as a detention system to decrease the Concórdia flood problem, and until today the dam was submitted to several events, that were responsible by the flow that passed for the spillway.