Conclusion
In this study, the physical process of three major rainfall derived
infiltration and inflow (RDII) sources: roof downspout, sump pump, and
leaky lateral, were investigated using physics-based models. These three
sources represent three different flow patterns through: a direct
connection of runoff catchments, course porous media, and compacted
soil, respectively. The typical flow response of each RDII source was
expressed as impulse response functions (IRFs) that indicate the flow
responses to a representative rainfall. Three IRFs were superposed to
produce the total RDII flows and the weighting factors of each IRF were
calculated using the actual sewer flow data in a few neighborhoods in
Illinois based on a genetic algorithm (GA) technique. The results can
shed light on identifying the contributions of different RDII sources in
a sewershed that enables decision makers to better understand the local
RDII issues which in turn facilitates a more effective management of the
sewer system.