ObjectiveThis study aims to explore the major factors impacting the runoff control performances of impervious area disconnection system. The results are expected to provide a data foundation and scientific reference for hydrological design and benefit assessment of impervious area disconnection system in the process of sponge city construction.

MethodIn April to October 2017, at the Jiufeng artificial rainfall laboratory of Beijing Forestry University, impervious area disconnection system was constructed by filling the soil tank (4 m long × 0.6 m width × 0.25 m height) with sandy loam soil from Beijing West Mountain. Based on the artificial rainfall experiments, the runoff control effects of impervious area disconnection system with different ratios of green space areas (25%, 50% and 75%), green space construction methods (flat and with surface depression depth of 5 cm) and initial soil moisture contents (26%−30% and 35%−38%) were quantitatively evaluated using four indices including delay in initial runoff-yielding and peak discharge generation time, runoff and peak discharge reduction rates.

ResultThe results showed that the average initial runoff-yielding and peak discharge delay time of the 9 groups of impervious area disconnection system in this experiment were respectively 18 and 8 min, and the average runoff and peak discharge reduction rates were respectively 38.9% and 28.3%. The runoff control efficiency of impervious area disconnection system increased with the ratio of pervious areas. When the ratio of pervious areas increased from 25% to 50% and 75%, the average initial runoff-yielding delay time increased from 15 min to 23 min and 24 min, respectively, and the average delay in peak discharge generation time was 5, 5 and 15 min, respectively, and the average runoff reduction rate increased from 29.4% to 35.1% and 52.2%, respectively. The runoff control efficiency was greatly influenced by the surface depression depths. Impervious area disconnection system with pervious areas surface depression depths of 0 and 5 cm could reduce runoff by 20.3% and 52.3% in average, respectively, and the average peak discharge reduction rates were 12.8% and 35.4%, respectively. The lower the initial soil moisture content of pervious areas (26%−30%) was, the longer the initial runoff-yielding delay time (17 min) was, the higher the runoff and peak discharge reduction rates (44.1% and 39.1%, respectively) were.

ConclusionImpervious area disconnection system could effectively control runoff in urban areas by slowing down runoff, delaying initial runoff-yielding and peak discharge generation time, reducing runoff and peak discharge.