Evaluation of groundwater recharge in Poland using the infiltration coefficient method

Variable methods and results are reported on groundwater recharge in Poland. The evaluation of recharge on a small scale requires the use of a single method. In order to evaluate these outcomes and their distribution, the authors have decided to verify different approaches and select the infiltration coefficient by comparison. The article is an extension of the studies on groundwater recharge conducted by the authors. The main goal is to verify previously designed values of the infiltration coefficient based on groundwater runoff from additional river basins in Poland. Total groundwater recharge from precipitation in Poland was calculated at 34,118 km3 per year, which equals 109.3 mm of water column. The obtained value is close to the average multi-year value of the groundwater runoff. Recharge constituted 18.6% of average precipitation in Poland, which was calculated at 588.5 mm. The estimated groundwater recharge value was verified referring to groundwater runoff from 37 river basins with known discharge rates in the years 1976–2005. Differences in mean groundwater runoff for the entire area (37 river basins) obtained by the infiltration coefficient method and by the use of Wundt’s method amounts to only 0.7%. Despite the simplified calculation methods, the results obtained on a small scale are more accurate than other calculations, which are based on data pertaining to precipitation, soil type, land use, topography of the area, and depth to the groundwater.