Non-point source pollution is widely considered the most important cause of environmental decay in aquatic ecosystems around urbanized areas. Evaluating first foul flush phenomenon is crucial in order to prevent unwanted and untreated discharges from sewer overflows. The use of numerical models for stormwater analysis is well established for research and management: however they are used in complex systems mainly to evaluate flow rates. In this study the authors want to describe the quality of stormwater in rural and peri-urban centers with SWMM. Several buildup functions were implemented with the aim of modeling the accumulation phenomena and to calibrate a qualitative model of stormwater runoff in terms of pollution. SWMM allows continuous simulations using historical rainfall series, which can be applied on a verified model in order to assess the risk of bad management practices and to design sustainable strategies in rural and suburban areas. Furthermore this kind of model will be used for evaluating stormwater discharges into infiltration ponds (very common in rural or peri-urban areas) because usually they are not supported by a correct first foul flush investigation.
