Hydro-pedotransfer functions were derived for partly sealed areas from lysimeter studies and inner-city percolation experiments.The annual percolation rate of urban sites (Du) considers boththe percolation rate from sealed areas (Ds) and unsealed areas (Da):Du=α Ds + (1-α) Da (1) The percolation rate of unsealed areas can be calculated easily using recently developed hydrotransfer equations of Wessolek et al.2007.They use easily available data such as winter and summer precipitation,plant available water and potential evapotranspiration.For sealed areas a sealing index α (=percent sealed areas/100) must firstly be predicted by using either mapping methods or remote sensing data.In the next step we suggest using β-infiltration coefficients to express both (i) the runoff leaving the sealed surface and (ii) the amount of rainfall that infiltratesinto the seam material or through fissures in the soil.