Cumulative effect of the disconnection of impervious areas within residential lots on runoff generation and temporal patterns in a small urban area

This study sought to evaluate the cumulative effect of the implementation of green space depressions to promote disconnection of impervious areas within residential lots on runoff generation and temporal patterns in a small urban area characterized by high imperviousness. Three hypothetical scenarios were proposed with variations in the disconnection rate (α) within the lot, the soil infiltration conditions, and the rainfall patterns. Simulations were performed using the Storm Water Management Model (SWMM) with the implementation of a high spatial resolution model which allowed the explicit representation of the routing runoff between distinct surfaces. The results revealed a linear relationship trend between the total amount of rainfall (P) and total runoff (q), with identification of a possible precipitation threshold above the point at which a more critical condition of runoff generation is established. The value of this threshold was shown to be dependent on the degree of efficiency of the receptor permeable areas, which is associated with the disconnection rate and infiltrability of the soil. The results also showed that for a very high disconnection rate and lower infiltrability, runoff can increase substantially, with significant changes in the hydrographs simulated for longer storm events.