Análise do refluxo da rede de drenagem pluvial com base em modelo altimétrico durante períodos de cheias no município de Itaqui – RS

Abstract

The city of Itaqui, west border of the state of Rio Grande do Sul, located next to the Uruguay river banks is often hit by river floods, causing damages to the population and the local government. In addition to all problems caused by flooding, in times of floods occurs counterflow in the Rainwater network causing flooding in non floods zones, as was observed during na in site visit in the last flood. Within the presented context the main objective of this work is to realiza an analysis of the counterflow of the drainage network of the city of Itaqui during the floods in urban areas. After defining the area of study through the analysis of the data of the drainage network of the city and visits to the affected area during the flood period, were determined the orthometric altitudes of points of interest linked to the SGB through GNSS altimetry using the static relative method and also were accomplishment the quota tie to the SGB, so that the data is in an unique reference. From this information, and the Digital Elevation Model of the study area, it was identified that the points with counterflow occurrence have orthometric altitude linked to the SGB varying between 54,620m and 55,920m, the highest quota of floods in the city is 57,144m in the year 1983. Thus, with the drowning of the section of the gallery closed by the increase of the level of the river, the rainwater drainage system that connects the mouths of the wolf to the river, directs the flow of the waters of the river to the urban perimeter of the municipality seeking the balance of pressures in the system and causing flooding. The presented methodology proved efficiency for counterflow analysis in the drainage network of the city of Itaqui. The determination of MDE altitudes, of river and channel in a single reference allowed to analyze sites with occurrence of counterflow and floods.