Bidimensional modeling for the hydraulic verification of the channeling of a stretch of the fragoso river in olinda (Pernambuco, brazil)

Abstract

The densification process in cities causes the loss of natural environments, consequently reducing the permeable areas, increasing the phenomena of urban floods. Mitigation measures generally involve high costs and are not always reliable, due to uncertainties in the design and natural variables that are difficult to control and quantify, mainly related to climate change. In this scenario, the Fragoso River basin, located mostly in the coastal city of Olinda, recently registered floods that affected extensive areas, causing the government to carry out canalization and widening the river channel. Thus, this work aims to evaluate the reliability of structural measures implemented in coastal and low elevation urban environments, subject to tidal variations. For this, the following softwares were used: HEC-GeoHMS for processing geospatial topography data, with high resolution data; HEC-HMS 4.2.1 for hydrological modeling; and HEC-RAS 5.0.3 for two-dimensional hydraulic modeling, with representation of flood spots through the RAS Mapper tool. The rainy event of May 30, 2016 was simulated for two scenarios: the current one, in the natural conditions of the river; and the future, with the enlargement and channeling work designed. The results showed that the intervention would be hydraulically satisfactory, would allow the flow of flows, would reduce about 42.32% of the flooded urban areas, but would not prevent the flooding of marginal areas that are naturally very low.