Hydrological Performance of Green Roofs in Urban Areas Exposed to Extreme Rainfall Events

Abstract

How do green roofs influence stormwater runoff in urban areas exposed to increasingly extreme rainfall events? This paper evaluates hydrological performance of green roofs under changing climatic conditions characterized by more frequent short-duration, high-intensity precipitation. The study focuses on Central European urban environments, where rainfall extremes increasingly challenge conventional drainage systems. The methodological approach combines analysis of long-term precipitation time series with synthesis of theoretical knowledge and experimental data on green roof hydrological responses to different rainfall types. Results demonstrate that green roofs enhance rainfall retention and delay runoff peaks during common and moderately intense precipitation events, reducing instantaneous loads on urban drainage infrastructure. However, during extreme, rapidly occurring rainfall events, retention capacity becomes limited, revealing functional thresholds. From an urban planning and architectural perspective, these findings highlight the need for systematic implementation of green roofs as an integral component of climate adaptation strategies reducing urban vulnerability to rainfall extremes.