THE INFLUENCE OF “GREEN” ROOFS ON THE QUALITY OF RAINFLOW IN THE URBAN ENVIRONMENT

Abstract

The results of research aimed at assessing the quality of runoff from ‘green’ roofs as a source of pollutants, particularly heavy metals, are presented. It is justified that the majority of scientific studies dedicated to studying the quality of stormwater from “green” roofs indicate that these systems can improve the quality of runoff by reducing the concentration of pollutants and enhancing water balance regulation in urban areas. The results of research confirming the change in pH values in stormwater from “green” roofs compared to rainwater are provided. The influence of vegetation types and substrate composition of “green” roofs on the physicochemical composition of rainwater is analyzed. It is shown that “green” roofs with a dual substrate, where a mixture of activated carbon with perlite and vermiculite can be used as an adsorption layer, are effective in absorbing organic substances, heavy metals, and all forms of nitrogen for varying intensities of rainfall. The impact of the age (duration of use) of the “green” roof on the quality of runoff is analyzed. It is mentioned that the lowest quality of runoff is observed in the early stages of “green” roof operation, but water quality generally improves over time as the substrate and vegetation stabilize within the ecosystem conditions. It is shown that the quality index of runoff from a “green-blue” roof is higher compared to a ‘green’ or traditional roof. The results of scientific research confirming the effectiveness of “green” roofs in terms of changing the concentration of organic substances (COD, BOD), heavy metals, nitrogen, phosphorus, pH, and turbidity are presented. The main factors influencing the quality of surface water runoff from “green” roofs are justified and proposed. A diagram illustrating the circulation of pollutants in the “green” roof system and the potential of different factors acting as sources or absorbers of pollutants is provided.

Keywords

• “green” roof
• runoff quality
• stormwater management
• filtration
• rainwater
• influencing factors
• roof age