The hydrology of a small quaking fen was investigated by measuring all components of the water budget. Water-level measurements indicated that the fen is a focus for groundwater discharge, and that there is a lateral (subsurface) flow from the fen toward surrounding areas during most of the year. The hydrology, however, is strongly influenced by man, as water tables are maintained during dry periods by pumping water into the area. This action results in a reversal of flow patterns as surface water from a ditch inf'dtrates the fen and groundwater recharge occurs.
Two approaches for calculation of groundwater and surface water terms were compared. The two procedures differ in the way that vertical and horizontal hydraulic conductivity of the soil is calculated. Hydraulic conductivity estimated from in situ tube experiments was one to two orders of magnitude lower than hydraulic conductivity estimates from numerical water budget analyses.
Four one-month periods were selected for calculations of complete water budgets. Results of calculations of water flow were compared in respect to the overall error in the water budget (calculated as percent difference between inputs and outputs). Water budgets calculated from data on hydraulic conductivity gave high residual errors (56.1°70 + 16.3°70). When hydraulic conductivity was derived from numerical analyses, the errors were very small (2.8°7o + 3.1070) and the difference between inputs and outputs over a period of 127 days was only 2.6 mm (0.45o7o).