Hydraulic Planning in Insular Urban Territories: The Case of Madeira Island—Ribeira Brava

Sérgio Lousada,José Manuel Naranjo Gómez,José Cabezas,Rui Alexandre Castanho

doi:10.3390/w13212951

Abstract

The main objective of this study was to analyze the flood propensity of the main watercourse of Ribeira Brava drainage basin and, if necessary, to suggest two methodologies to mitigate the impacts, i.e., detention basin sizing and riverbed roughness coefficient adjustment. For the flood propensity assessment, geomorphological data obtained from the watershed characterization process was used through the SIG ArcGIS software and then used for the calculation of the expected peak flow rate for a return period of 100 years using the Gumbel Distribution. Finally, the drainage capacity of the river mouth was verified via the Manning-Strickler equation, with the purpose of establishing whether the river mouth of the watershed has the capacity to drain the entire volume of rainwater in an extreme flood event. In summary, the results indicate that the river mouth of the Ribeira Brava watershed does not have the capacity to drain the rain flow for the pre-established return period; therefore, the detention basin was sized using the Dutch Method and the Simplified Triangular Hydrograph Method, and the roughness coefficient was adjusted in order to ensure the increase in the river mouth’s drainage capacity.

Highlights

Despite the economic and technological development after the Industrial Revolution, the Earth has constantly suffered from the effects of anthropogenic actions
To evaluate the morphometric characteristics of the main watercourse of Ribeira Brava, an individual analysis of each of the parameters listed in Table 1 was undertaken, correlating them with reference values suggested in several bibliographies
Because the primary objective of this research was to verify the need to implement simplified measures to mitigate the impacts of floods in the Ribeira Brava watershed, the use of the detention basin proved to be effective in controlling the flow at the river mouth, which can be characterized as a structural measure [32]

Summary

Introduction

Despite the economic and technological development after the Industrial Revolution, the Earth has constantly suffered from the effects of anthropogenic actions. Extreme climatic phenomena have become one of the main problems faced by humanity, and floods are the most frequent of these events in regions with high urbanization [1,2,3,4]. Living with flood events has become increasingly intolerable over time, increasing the risk to human and economic loss [5]. Must be highlighted that this non-absorption of precipitation by the soil can occur both by the saturation process and by the waterproofing of the land [10]. In this context, due to the increase in the urban network in regions that were previously floodplains, there is an increase in the magnitude of the negative consequences in a densely urbanized region [11]

Objectives

Methods

Results

Discussion

Conclusion