Characteristics of thermal pollution from stormwater runoff from impermeable/permeable pavement surfaces via a lab-scale experiment.

Thermal pollution from stormwater runoff has been the focus of many studies in recent years due to its potential harm to aquatic microorganisms. However, there were few studies on the thermal pollution caused by stormwater runoff from various types of urban pavement surfaces. A lab-scale experiment was conducted to compare the thermal load of stormwater runoff from impermeable and permeable pavements and the influencing factors were investigated. The experimental findings demonstrated that the rainfall return period and initial temperature of various pavement surfaces significantly impacted the thermal load. The stormwater runoff absorbed more heat as the initial temperature, and rainfall return period increased. The difference of the thermal load of stormwater runoff between permeable brick pavement (PBP) and the impermeable asphalt pavement (IAP) increased from 305.26 to 436.70 kJ/m, when the initial surface temperature rose from 35 to 47 °C. The average runoff temperature decreased by 1.39-1.90 °C for PBP compared to the IAP, with an increase in surface temperature from 35 to 47 °C. Under the various initial surface temperatures, the mean temperature of the infiltration effluent from the PBP was 3.12-4.20 °C lower than the average temperature of stormwater runoff from the surface layer. Therefore, a PBP can effectively alleviate thermal pollution from stormwater runoff and safeguard the receiving waters' quality.