An analysis was conducted of the activity of individual homogeneous Hydrological Response Units (HRUs) and their impact on the components of the spatially distributed water balance based on the example of two urbanised catchments of the city of Poznań (Western Poland). Water balance was developed using the WetSpass model and GIS spatial data, based on hydrometeorological data from the reference period of 1961–2000 including projected land usage changes and precipitation changes expected by 2025 in the city. The catchments were parameterised with reference to land usage, soil permeability, terrain declivities and the level of groundwater waters in summer and winter. The dependence between HRUs and their impact on components of the water balance was determined. Water balance forecasts have shown two-way changes in the components of approximately 12% of the catchments. A significant increase of surface runoff (an increase of 20–30 mm/HRU) at the expense of effective infiltration reduction (by 15–20 mm/HRU) was determined for arable land intended for development. An increase of infiltration and evapotranspiration at the expense of the surface runoff reduction is forecast for areas designed for urban afforestation. The tendency of increase of atmospheric precipitation within the city until 2025 was indicated by changes in the water balance components. Changes in the landscape resulting from urban expansion may lead to detrimental hydrological effects: accumulation of surface runoffs and occurrence of local flash flooding, as confirmed by the simulations carried out using the WetSpass model. The results may contribute to a more accurate understanding of the impact of urban landscape modification patterns on the water balance at the regional and local scale.

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The aim of the study was the analysis of the integration of a flood risk management and water protection system in a selected section of the Warta Valley with taking into consideration the guidelines of the Water Framework Directive and the Floods Directive. The structure of the valley is comprised within a distance of 201.1 km by stretches of: an urstromtal, between the towns of Konin and Śrem, and the Warta gorge stretch between Śrem and Oborniki. High environmental values of the valley are shown, related to the presence of conservation areas and, on the other hand, a high flood hazard risk, resulting e.g. from advancing land development in the valley and its low retention capacity. The Integrated Water Resources Management guidelines conception was used in the analysis, inlcuding pointing out the directions of relations between minimizing flood risk and protection of natural values of the Warta River and its valley. Spatial distribution of the flood hazard and risk in the Warta Valley was also analyzed. A detailed analysis covered activities of a technical and non-technical character intended to stop the growth of flood risk. In the field of water conservation, the considered objectives included: achieving and maintaining a good ecological potential of waters or the risk of failing to achieve it, which is determined by a high urbanisation ratio, draining of an open-pit lignite mine, extensive morphological change in the river bed and pollution discharged into the waters from land used for agriculture. The results proved that one PRACE GEOGRAFICZNE