Ocena gospodarowania wodą na wybranych obszarach dolinowych Wielkopolski

The paper presents an assessment of changes in water resources in the areas of two polders – Nielęgowo and Zagórów – located in the Wielkopolska region. Changes in water relations of the surveyed valley areas were analyzed on the basis of the position of groundwater table and water supplies in the top layer of soil. Detailed analysis of the results of measurements carried out in two in terms of wet, dry, and growing seasons of 2008 and 2012 showed a difference of stocks in the upper layers of soil moisture of valley areas. Changes of water backup and groundwater levels were associated with the course and distribution of precipitation in the analyzed periods of vegetation. In Zagórów polder the amount of precipitation in the winter half-year, preceding the analyzed vegetation period of 2012, has also affected the size of the water supply and the state of groundwater. Positions located in the upper parts of Zagórów polder were characterized by the greatest amplitude of fluctuations in water table levels. However, in the positions located in the lowest points, the amplitude of the fluctuations in water level amounted to 0.9 m on average. There were also differences in the stocks of water in the upper layers of soil. The largest reserves of water were found in the lowest-lying parts of the polder, where the maximum water supplies ranged from 305 mm to 364 mm. On the basis of statistical analysis, the purpose of which was to determine the relationship between the supply of water in the top layer of soil and groundwater conditions in valley areas found that from 81% to 90% of the total variability in the water supply was dependent on the level of fluctuations in the groundwater table.