The basin of the Służewiecki Stream, hydrologically uncontrolled, is urbanised, but it has a mosaic-like character, consisting of urban and agricultural land use. This is shown by the graph of the basin and its subcatchments that takes into account the changes of the runoff coefficient in its subcatchments. The land cover changes in 1993–2002 and the forecast for the years until 2012, together with the calculated rainfall hyetograph are input elements to the rainfall-runoff model. The isochrone method with the Kirpich equation constitute the transforming function, and the runoff hyetographs are the output elements from the system. The paper presents also practical problems occurring in the implementation of the recommendations of the local spatial plan as well as consequences resulting from disregarding the recommendations.