PERFORMANCE ANALYSIS OF OUTPUT DEVICES FOR DETENTION RESERVOIRS IN URBAN FLOOD CONTROL IN FORTALEZA

Abstract

Hydrological and hydraulic studies are required to understand the dynamics of floods and to control their impacts, in order to better target effective alternatives, mainly in urban areas that are most often achieved by the harmful effects of excess runoff. In general, these studies are based on the estimate of the maximum flows that are reached in critical points of the hydrographic basin, in order to choose the hydraulic devices that transfer or mitigate their effects. In this perspective, it is necessary to simulate alternatives for inference of performance for the purpose of effective control of floods. This work focuses on evaluating the performance of various combinations of outlet devices, notably orifices and spillways of various sizes, applicable to detention reservoir, a compensatory technique based on the temporary storage of the excess flow, with two basic objectives: to reduce the peak flow rate and to delay peak time. In the development of the work, the empirical IDF (intensity-duration-frequency) relationship of Fortaleza (CE) is used to obtain the project hietograph and SCS model (Soil Conservation Service) is used to elaborate the inflow hydrograph to the reservoir. The Puls method is employed to generate the flow propagation. The methodological process is oriented towards decision in the choice of the device to be adopted in the executive project of the facility. The results show different levels of reservoir performance, according to the selection and dimensioning criteria of the hydraulic elements promoting the effluent hydrograph.