Developing countries suffer with the growth of the so-called irregular cities. The lack of basic infrastructure and the inadequate urban growth management lead to urban flood problems. The concept of risk combines the probability of a hazard event with the consequences inflicted to a system. Thus, there are several possibilities of acting in flood risk mitigation: reducing the hazard and/or the system vulnerability. In this context, both structural measures and non-structural measures may be used. Traditional structural measures frequently were associated with river canalisation, dykes and dams. In the last past decades, the concepts of sustainable drainage systems have arisen, tending to control onsource runoff generation. The urban occupation of the city is very dense, with few open spaces and degraded areas. In the overall assessment, river restoration concepts, although limited by the built environment, produced a minor flood risk index, when compared with a traditional alternative. Keywords: flood risk, risk assessment, river restoration.