Use of hydrologic and hydraulic modeling for optimizing an existing detention pond

Abstract

In Brasilia the local regulations limit the maximum flow rate per unit area discharged in rivers by drainage systems. The purpose of this work is to analyze the possibility of optimizing the use of an existing detention pond, known to be oversized, by directing to it the stormwaters of adjacent areas not attended by any urban drainage system. SWMM, a hydrologic and hydraulic model, was used to design a new urban drainage system and to analyze it with the detention pond at the outlet. As a result, the new system designed complies with all local regulations including maximum flood peak for the design critical rainfall. However, the original drainage system for the area needs improvements considering that there were flooded manholes for all rainfall events tested. The flooding is clearly seen with the 2D modelling. It is shown that the existing detention pond can attend the studied area by adapting part of its area. This study showed the importance of hydrological and hydraulic modelling in urban drainage to manage this system and to propose sustainable measures – such as ponds.