Factors determining range and tendencies of groundwater level changes in Kampinos National Park wetland areas

The marsh zone areas include about 2,440 km2 in Kampinos National Park, which amount nearly 30% of park and its buffer’s surface. The specific characteristic of the KNP marsh zones is presence of shallow groundwater; mean depth to groundwater table is formed from 0.16 do 2.30 m. Range and tendencies of groundwater level changes in marsh zones are related to the influence of geogenic and anthropogenic factors. Among geogenic factors, the most important sense have distribution and seasonality of precipitation, which determine the value of infiltration recharge, evapotranspiration and watercourse drainage of shallow groundwater system. The basis of the researches on defining the role of factors determining range and tendencies of groundwater level changes in KNP, has been regular monitoring observations conducted in the park since 1999. The results of correlation indicate on high diversification of relation: atmospheric precipitation – depth to groundwater level. Determination of trend on the different significance levels provides detaching areas where relation between groundwater levels and precipitation is so high that influence of other environmental factors indicating on depth to groundwater table could be skipped and areas where the relation is so low, which indicates on influence of various factors. Groundwater level in marsh areas are characterized by large dynamic of changes. Since 1999, the beginning of the observations, downward trend of groundwater table has been observed, after 2003 the character of trend has been conversed. Another decreasing trend has started in 2007 and with assumption of previous tendencies, its inversion will occur after 2011 (after extremely dry year). Geostatistical analysis of spatial difference of mean year amplitude of depth to groundwater level enabled the assessment of surface water influence on groundwater level changes. The areas of highest value of amplitudes are localized in southern part of northern marsh belt and central part of southern marsh belt. Anthropogenic factors such as: water withdrawal and improper draining system, have not changed in recent years, so their influence can be called as “steady” and acceptably to eliminate in case of elaborating of programs of wetland areas renaturalisation.