Avaliação hidrológica e estimativa de vazão de projeto para macrodrenagem urbana.

Abstract

The urbanization procedure generates major changes in the natural environment, particularly modifying land use and worsening the problems of urban floods, in a cycle of cause and effect that accumulates important economic and social losses. This research aimed to carry out hydrological assessments and estimates of intense rainfall and project flow through the Santa Bárbara and GRADEX models and dimension a macro-drainage channel in the peri-urban basin of the Frango stream, tributary of the Espinharo river, in the city of Patos- PB. The methodology used was subdivided into two parts, one referring to the use of geoprocessing to characterize the chicken stream basin, and the other concerning the hydrological and hydraulic analyzes and estimates. With the application of geoprocessing, geomorphological information of the basin was obtained using GIS software. In the analysis and hydrological estimates, daily rainfall data obtained from the ANA (National Water Agency) and the State Water Management Executive Agency (AESA) database were used to create the maximum daily rainfall historical series and model the equation from the rain. The number of the curve of the CN basin equal to 79 and the average concentration time of the basin equal to 60 minutes were obtained. The use of the Huff method indicated that the rains in the first quartile are more intense at the beginning of the event and when the return period is longer, the rain peak with the same duration increases. It was found that for a critical rainfall of 60 minutes and a return period of 50 years, using the flow rates of the GRADEX and Santa Bárbara methods, the channel of the chicken stream would be subject to failures with overflow. The use of the GRADEX method resulted in consistent estimates of design flow rates, where lower concentration times overestimate flow values. However, it presents itself as an important tool for hydrological and hydrological planning in the dimensioning of macro-drainage projects aimed at controlling and preventing floods.