What is Insular Territories

This study aims to examine the flood propensity of the main watercourse of Porto da Cruz drainage basin and, if relevant, to propose two methodologies to alleviate the impacts (i.e., detention basin sizing and riverbed roughness coefficient adjustment). Geomorphological data were obtained from the watershed characterization process and used through the SIG ArcGIS software for the flood propensity assessment and then for the calculation of the expected peak flow rate for a return period of 100 years through the Gumbel Distribution. Subsequently, the drainage capacity of the river mouth was verified using the Manning‐Strickler equation in order to establish whether the river mouth of the watershed has the capacity to drain the entire volume of rainwater in a severe flood event. In conclusion, the results demonstrate that the river mouth of the Porto da Cruz watershed does not have the capacity to drain the rain flow for the predetermined return period; thus, the detention basin was sized through the Dutch method and the simplified triangular hydrograph method.