Reviewing Design Criteria for Flood Control Reservoir: A Case Study of Pirajucara River in the City of Sao Paulo

Design criteria for flood control infrastructures is based on intensity duration and frequency equations (IDF), considering future scenarios of urbanization. In some situations, flood control systems do not work properly due to the lack of urban drainage planning and management. Sao Paulo City is an example. Its population growth was not accompanied by the urban infrastructure in the last century. As a result, there has been many damages from intense rainy events. Floods areas are increasing every year, in this situation it is very important to improve the flood control measures in the city. Sao Paulo metropolitan region is provided with more than fifty flood protection reservoirs that are being implemented since the 90s. For the majority of those reservoirs the inlet structure is a fixed weir and their efficiency is directly linked to the design criteria applied to design it. Recent evaluations with historic data identified that multiple systems of reservoirs are being either super or underutilized. This study proposes a method to improve the design of these structures coping with future urbanization scenarios. The case study is located in the Pirajucara Basin. This basin has a system of six flood control reservoirs, one of them is called Sharp reservoir. This paper presents the analysis of Sharp efficiency based on five recent rainfall events and suggests hydraulic improvements in its hydraulic control.