Impacts and sensitivity analysis of imperviousness area and connectivity on surface runoff under a plot‐scale rainfall simulation experiment

Abstract

AbstractUrbanization has had a major impact on runoff process, which is not fully understood. In this study, a plot‐scale rainfall‐runoff simulation experiment was conducted in an experimental field to evaluate the effects of imperviousness and its connectivity on surface runoff. A total of 11 underlying surface scenarios with different impervious area and two imperviousness connectivity conditions were designed. For each scenario, two rainfall intensities and two initial soil moistures were applied. The results show that the relationship between the surface runoff coefficient and the impervious area under fixed imperviousness connectivity, rainfall intensity, and initial soil moisture represents a strong linear trend. With high antecedent soil moisture, imperviousness arranging in disconnected pattern can lead to initially lower but later higher outflow rate compared to imperviousness arranging in connected pattern. The sensitivity of the runoff coefficient to impervious area, which represents increased runoff coefficient per unit impervious area, is negatively related to the rainfall intensity as well as the initial soil moisture but positively related to the imperviousness connectivity. These results indicate that the impacts of the impervious surface on runoff are not only related to its connectivity, but also the original soil condition before sealing: the higher infiltration capacity of the original soil, the greater hydrological impacts caused by soil sealing.