ABSTRACT Flood events are one of the major causes of economic loss and the loss of life worldwide. Unfortunately, their occurrence has become increasingly more frequent and of greater magnitude. In order to minimize the population’s exposure to danger, it is necessary to invest in tools that aid in the decision-making process related to urban drainage management. The present work proposes a methodology for the construction of a Flood Hazard Chart for urban watersheds. The Storm Water Management Model (SWMM) was applied to the Cachoeirinha Watershed (Belo Horizonte, Brazil). The model was calibrated and validated using precipitation data and water levels recorded in monitoring stations located in the study area. The Nash-Sutcliffe Coefficients for the calibration and validation were 0.72 and 0.70, respectively. The performance of the model was satisfactory, although the model was not able to represent the more intense rain events that led to emergency and overflow warnings. Modeling results allowed the construction of the hazard chart, which defined hazard ranges or warning levels of hazard as a function of accumulated rainfall and duration. The constructed graph was assessed from real precipitation events and proved to be valid, since most events corresponded with the defined warning levels in the chart. The Flood Hazard Chart proposed in this research is a valuable tool for flood risk management as it has the potential to reduce exposure to flood disasters.

ABSTRACT Flood events are one of the major causes of economic loss and the loss of life worldwide. Unfortunately, their occurrence has become increasingly more frequent and of greater magnitude. In order to minimize the population’s exposure to danger, it is necessary to invest in tools that aid in the decision-making process related to urban drainage management. The present work proposes a methodology for the construction of a Flood Hazard Chart for urban watersheds. The Storm Water Management Model (SWMM) was applied to the Cachoeirinha Watershed (Belo Horizonte, Brazil). The model was calibrated and validated using precipitation data and water levels recorded in monitoring stations located in the study area. The Nash-Sutcliffe Coefficients for the calibration and validation were 0.72 and 0.70, respectively. The performance of the model was satisfactory, although the model was not able to represent the more intense rain events that led to emergency and overflow warnings. Modeling results allowed the construction of the hazard chart, which defined hazard ranges or warning levels of hazard as a function of accumulated rainfall and duration. The constructed graph was assessed from real precipitation events and proved to be valid, since most events corresponded with the defined warning levels in the chart. The Flood Hazard Chart proposed in this research is a valuable tool for flood risk management as it has the potential to reduce exposure to flood disasters.

ABSTRACT On-site stormwater detention – OSD has been constructed in big Brazilian cities, as a way to reduce the impact of urbanization on the drainage system. However, there are a few studies about its efficiency in real scale. This article aims to compare the monitoring data of an OSD built in a hospital in Belo Horizonte and the results determined by theoretical methods, commonly used in the design of this structure. Inside the OSD was installed a level sensor to monitor water level during rain events. The data was recorded on a data logger every 30 seconds during the period April 2015 to March 2017. It was analyzed the OSD filling during the occurrence of 48 precipitation events. In the maximum heights of water level comparison, it was found that the monitored values were higher than theoretical values and the results using Rational Method were closer to monitoring data than the results with SCS-HU Method. It was also found that the peak and recession time calculated with Rational Method represented better the water levels monitored.

ABSTRACT On-site stormwater detention – OSD has been constructed in big Brazilian cities, as a way to reduce the impact of urbanization on the drainage system. However, there are a few studies about its efficiency in real scale. This article aims to compare the monitoring data of an OSD built in a hospital in Belo Horizonte and the results determined by theoretical methods, commonly used in the design of this structure. Inside the OSD was installed a level sensor to monitor water level during rain events. The data was recorded on a data logger every 30 seconds during the period April 2015 to March 2017. It was analyzed the OSD filling during the occurrence of 48 precipitation events. In the maximum heights of water level comparison, it was found that the monitored values were higher than theoretical values and the results using Rational Method were closer to monitoring data than the results with SCS-HU Method. It was also found that the peak and recession time calculated with Rational Method represented better the water levels monitored.