Estudo hidrológico em seção do canal de macrodrenagem do Riacho do Frango - Patos/PB.

Abstract

The disorderly urban growth of cities has been causing serious problems for the maintenance and management of water resources, being a determining factor for social and economic development. As the urban fabric advances and occupies spaces, there is an increase in soil impermeability and the risks of floods and inundations, resulting in significant losses for society. Thus, this study aimed to perform a hydrological analysis of the Riacho do Frango watershed in the city of Patos, PB, conducting a critical investigation into the hydraulic behavior and drainage capacity of the region, considering project precipitations with different return periods. The methodological process involved the survey of geomorphological characteristics and land use in the watershed, using geoprocessing tools. Additionally, hydrological parameters were determined based on the annual series of maximum daily rainfall obtained from the database of the National Water and Basic Sanitation Agency (ANA). From the watershed characterization, the curve number (CN) was determined to be 86, and the time of concentration for the study area was found to be 54 minutes. For the temporal distribution of rainfall, the Yen and Chow method was used, considering the occurrence of critical (or peak) precipitation for periods close to half the duration of the rainfall. Finally, a return period of 30 years and a duration of 90 minutes were chosen for estimating the design flow using the Soil Conservation Service (SCS) method, with the Microsoft Excel and HEC-HMS hydrological modeling software. The generated design hydrographs showed peak flows of 111,5 m3/s (Microsoft Excel) and 120,0 m3/s (HEC-HMS). Regarding the calculated maximum flood depths for the Frango Channel, considering standard sizing rules for rectangular channels, values were obtained as 3,8 m (Microsoft Excel) and 4,0 m (HEC-HMS).