Flood analysis in the Canoas, Sertão, and Mampituba rivers in the South of Brazil through hydrological and hydrodynamic modeling

Abstract

Floods that occur in hydrographic basins with high slopes are more susceptible to natural hazards due to the occurrence of high intensity hydrological events and the type of sloping relief. These two associated factors contribute to an increase in the destructive potential of these regions, causing economic damage and loss of life for people and animals. This study sought to assess the floodplain areas in the Canoas, Sertão, and Mampituba Rivers that contribute to the Mampituba River basin in southern Brazil, to support emergency procedures for dealing with floods and contribute to the territorial management of these spaces. From the hydrological data of the Mampituba River basin, a hydrological model was used, which generated flows that were inserted as input to a hydrodynamic model, resulting in flood patches in the plains of the modeled rivers. The calibration and integration studies of the models were carried out on a computational platform that employs the hydrometeorological knowledge represented by the models of the basin under study. The hydrodynamic modeling represented in the maps indicated that the flooding patches occur within the river channels and in the plains occupied by agriculture, with a predominance of irrigated rice paddies, pasture fields, forestry, urbanized areas, and native vegetation. In the urban region along the floodplains of the Praia Grande and Mampituba Cities, there are inns, restaurants, and residences which can suffer structural damage and expose people to the danger of a flood event of this magnitude. The results achieved allow us to infer that the integrated modeling system proved to be capable of performing efficient hydrological and hydrodynamic simulations. The methods used can be replicated in other basins and the results can support public managers for greater assertiveness in decision-making when facing the dangers of extreme weather events.