In modern urban drainage systems, stormwater detention facilities are important tools to reduce flood effects and discharges of uncontrolled pollutants into water receivers. For their design, simplified methods and continuous simulations of observed data are generally used. One of the main targets is to limit the frequency and the entity of overflows. In this article, a probabilistic approach for the derivation of the distribution functions of spilled volumes to evaluate the efficiency of a stormwater detention facility is proposed. The possibility of pre-filling of the storage capacity from a previous rainfall event, which can increase the probability of overflows from the stormwater detention facility, has been considered. The effects of the simplified assumptions have been deeply investigated and discussed. Final expressions have been applied to a case study, and results have been compared to those obtained from the continuous simulation.
pre-filling, probabilistic approach, spills, stormwater detention facilities
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