This study proposes a method for estimating the flood risk in a tropical basin. The novelty consists of using two dynamics variables represented by the precipitation and the land use and land cover (LULC) to obtain the effective rainfall and its exceedance probability. The flood risk is determined by using deterministic depending on the exceedance probability of effective rainfall. Two time series of precipitation were involved. The first precipitation time series was used to prove the method corresponding to the months of the rainy season obtained from 58 gauging stations during the period 1980–2000. The second precipitation time series was applied for the validation stage of method corresponding to the period 2015–2018. In the validation stage, it has been found that there is a slight difference between the principal component N° 1 in the first time series with respect to the second time series. The method represents a contribution to determine the spatio-temporal distribution of flood risk that allows to take decisions to achieve preventive measures that contributes to the protection of human being and goods.