The paper presents the characteristics of shallow groundwaters of the Polesie National Park – one of five national parks in Poland, where main subjects of protection are water-peatland ecosystems. Its functioning depends on the state of water resources. Data from field mapping at the turn of July and August 2013 used for the analysis show untypically high location of groundwaters in the summer period. Such a situation was caused by abundant atmospheric alimentation that occurred in spring and early summer of the analysed year.
The paper discusses the water resources of the Krężniczanka River catchment. The catchment with an area of 224.9 km2 is located south-west of Lublin. The characteristics of the groundwaters and runoff were determined based on hydrological and hydrogeological materials of the Department of Hydrology of the Maria Curie-Skłodowska University (UMCS). Mean runoff in the period from 2010 to 2016 amounted to 125.7 mm, precipitation 629.4 mm, and evapotranspi-ration 503.7 mm. A strong relationship was determined between the rhythm of runoff and ground-water level fluctuations. The contribution of groundwater supply in total runoff equalled 81.5%.