| Abstract: | Detailed modelling of the hydrological setting of fen meadows appears to be possible provided that detailed information on geomorphology, hydrochemistry and piezometric heads is available for a number of years. In the Laegieskamp, a small wetland reserve located in the central part of The Netherlands, a piezometric monitoring network was sampled for water quality analysis and piezometric heads between 1986 and 1992. Average yearly discharge and recharge periods were used for FLOWNET calculations. First, the models were used to determine, with the help of information on water quality, the hydrological systems in the study area. Secondly, they were used to define the present and past hydrological setting of a fen meadow in the reserve. The hydrological systems and water quality in the study area have changed considerably over the past 65 years. At present the fen meadow is mainly fed by precipitation. The mineral-rich conditions favouring the fen meadow vegetation are thought to be maintained thanks to a clayey peat layer and an oscillating shallow water body that prevents rapid leaching of minerals. The sulphate content in the fen exhibits a pattern of temporal variation, which is related to the severity of the annual drought. Our study showed that groundwater flow is mainly lateral, instead of the assumed vertical infiltration of groundwater in previous regional studies. This led us to the conclusion that conservation and restoration perspectives are much better than previously expected. The polluted middle, deep groundwater is not a major threat to this fen at the moment. © 1997 John Wiley & Sons, Ltd. |
