Evaluation of Permeable Brick Pavement on the Reduction of Stormwater Runoff Using a Coupled Hydrological Model

Performance synergism of pervious pavement on stormwater management and urban heat island mitigation: A review of its benefits, key parameters, and co-benefits approach

Pervious pavement system (PPS) is a suitable alternative technique for mitigating urban flooding and urban heat island (UHI) simultaneously. However, existing literature has revealed that PPSs cannot achieve the expected permeability and evaporation. To overcome this gap, this study presents an elaborate review of problems associated with PPSs and highlights its benefits to stormwater management and UHI mitigation. We determined key parameters of PPSs that could influence urban flooding and UHI mitigation, including hydrological properties, thermal physical properties, structure design, and clogging resistance. We identified the co-benefits approach of PPS towards performance synergism on stormwater management and UHI mitigation from quality controlled design and fabrication, periodic maintenance, and effective evaluation system based on practice environments. The results indicate that existing studies of PPSs primarily focus on permeability, while little emphasis is given to the evaporative cooling performance, leading to a biased development with a loss of test standards and regulations that cannot control the cooling potential of the system. The performance synergism of permeability and evaporative cooling in PPS should be studied further, while considering quality control of the materials and in-situ practice design. Parameter controls (with commonly used standards) during fabrication, periodic maintenance (during operation), and pre- and post-evaluation processes of PPSs should work collectively to achieve optimal benefits and reduced costs.

Community Scale Assessment of the Effectiveness of Designed Discharge Routes from Building Roofs for Stormwater Reduction

Urban flooding is increasing due to climate change and the expansion of impervious land surfaces. Green roofs have recently been identified as effective solutions for mitigating urban stormwater. However, discharge routes that involve receiving catchments of stormwater runoff from roofs to mitigate high flows have been limited. Thus, a hydrological model was constructed to investigate the effects of changing discharge routes on stormwater flow. Three hypothetical scenarios were assessed using various combinations of discharge routes and roof types. The reduction effects on outflow and overflow were identified and evaluated across six return periods of designed rainstorms in the Tai Hung Tulip House community in Beijing. The results showed that green roofs, together with the discharge routes connecting to pervious catchments, were effective in reducing peak flow (13.9–17.3%), outflow volume (16.3–27.3%), drainage overflow frequency, and flood duration. Although mitigation can be improved by considering discharge routes, it is limited compared to that achieved by the effects of green roofs. However, integrating green roofs and discharge routes can improve community resilience to rainstorms with longer return periods. These results provide useful information for effective design of future stormwater mitigation and management strategies in small-scale urban areas.

Assessment of Sponge City Flood Control Capacity according to Rainfall Pattern Using a Numerical Model after Muti-Source Validation

Urban floods are a common urban disaster that threaten the economy and development of cities. Sponge cities can improve flood resistance ability and reduce floods by setting low-impact development measures (LID). Evaluating flood reduction benefits is the basic link in the construction of sponge cities. Therefore, it is of great significance to evaluate the benefits of sponge cities from the perspective of different rain patterns. In this study, we investigated the urban runoff of various rainfall patterns in Mianyang city using the Strom Water Management Model (SWMM). We employed 2–100-year return periods and three different temporal rainfall downscaling methods to evaluate rain patterns and simulate urban runoff in Mianyang, with and without the implementation of sponge city measures. After calibration, model performance was validated using multi-source data concerning flood peaks and inter-annual variations in flood magnitude. Notably, the effects of peak rainfall patterns on historical floods were generally greater than the effects of synthetic rainfalls generated by temporal downscaling. Compared to the rainfall patterns of historical flood events, the flood protection capacities of sponge cities can be easily overestimated when using the synthetic rainfall patterns generated by temporal downscaling. Overall, an earlier flood peak was associated with better flood sponge city protection capacity. In this context, the results obtained in this study provide useful reference information about the impact of rainfall pattern on urban flood control by LID, and can be used for sponge city design in other part of China.