Hydrogeological Assessment of Urban Springs in Warsaw and Their Role in Green Space Management

Springs located in urban historic areas are important for groundwater management, the protection of green spaces, and the preservation of park functions and urban structure. This article presents the results of a study of selected Warsaw springs in the city center under conservation protection, focusing on their hydrogeological characteristics, hydrogeochemical analysis, and pressures associated with urban development. Field and laboratory analyses, as well as hydrodynamic modeling, made it possible to assess the quantity and quality of water from the springs. Hydrodynamic studies showed that the area of the spring recharge zone of 13.77 ha is characterized by an average time of water exchange of approx. 26 years and a low infiltration recharge, an average of 18 mm/year. Hydrogeochemical analyses showed that spring water has a complex, multi-ion hydrogeochemical type: Cl-SO 4 -HCO 3 -Ca-Na, Cl-HCO 3 -SO 4 -Ca-Na, Cl-HCO 3 -Na-Ca, and NO 3 -Cl-HCO 3 -Ca-Na, including the occurrence of hazardous substances such as PAH and BTEX, PCBs, non-ionic detergents, and heavy metals. The results indicate that urbanization significantly affects groundwater levels and spring recharge areas, which can limit the availability of water in green and recreational areas. The results of the study indicate the need for action to increase groundwater resources through managed aquifer recharge for rainwater management in densely built-up areas. In terms of water quality measures, due to the unsatisfactory chemical water status, the use of spring water for irrigation of urban vegetation or its incorporation into the active recreational infrastructure of the park currently appears to be fraught with considerable risk, hence the need to take protective action in the spring recharge zone through the regular monitoring of groundwater quality, the legal designation of protection zones, and the implementation of policies that support urban water retention. It is necessary to implement pre-treatment solutions (aeration, desalination) or introduce appropriately resistant vegetation. Any type of activity that allows the use of water after treatment will certainly contribute to making the park more attractive as a place of recreation and leisure for residents. Findings from the research can support decisions on protecting green spaces and adapting cities to climate change.