HYDRAULIC EFFICENCY OF SELECTED INTENSIVE GREEN ROOF SUBSTRATES

The rapid urbanization resulting in increased area of sealed surfaces distorts the natural water balance of urbanized ecosystems. Thus, the natural infiltration of surface water is reduced and the significant increase in volume surface runoff is being commonly observed. Water of surface runoff is usually collected and redirected by the stormwater systems to the natural surface water reservoirs, including also rivers and lakes, commonly without any treatment. So, a significant environmental threat to water quality posed by surface runoff from urbanized areas is obvious. This paper contains the attempt of numerical assessment of efficiency of six different commercially available substrates for intensive green roof. The numerical modeling of green roof efficiency was performed by the means of the finite elements modeling software FEFLOW, Wasy-DHI. The developed model reflected the cross section of the tested green roof. The required input data for modeling covered the saturated hydraulic conductivity and water retention characteristics and were based on information available in the technical descriptions of the tested substrates. The obtained results showed the diversified performance, due to different volume of retained water under the same boundary conditions, directly related to the properties of green roof filling substrates.