We used the finite difference code MODFLOW-SURFACT ( HydroGeoLogic, 2011) to obtain numerical solutions to Eq. (1) for the study area. The numerical model encompasses an area of 6.77 ha. Boundary segments are shown in Fig. 1. The segments to the north (inflow) and southeast

(outflow) were treated using head-dependent flux boundaries (General Head Boundary cells in MODFLOW-SURFACT). For the northern inflow boundary, external heads were specified using data from piezometer 45 (Fig. 1). No wells or piezometers were available to the south of the model domain. Therefore, external heads for the outflow boundary were estimated using the interpreted hydraulic gradient in the southeastern PF-562271 manufacturer part of the meadow (Fig. 1). During transient simulations the external boundary heads were varied using available time-series data, which allowed for realistic seasonal variations in the simulated boundary flows. Constant-head cells were used along the southwestern boundary to simulate inflow from the west arm springs. The remainder of the model boundary

was specified as no-flow, following the bedrock outcrop around the meadow. The total modeled Epigenetics inhibitor aquifer thickness is 27.7 m, which is the depth of permeable material determined by packer testing at the Crane Flat pumping well (Section 2). The horizontal grid spacing in most of the model domain is 2 m × 2 m.

Near springs in the southwestern part of the meadow we used larger grid cells. This part of the domain is more than 100 m from the main meadow area and detailed simulation of heads and flow directions was not necessary. The model column spacing was increased gradually from 2 to 10 m in this southwestern area. The aquifer thickness was discretized using seven finite-difference layers. Tacrolimus (FK506) Surveyed ground elevations were used to develop a TIN representation of the land surface. This surface provided a starting point to define the model layers. The top model layer has a uniform thickness of 1 m and is used to locally represent the peat body, which has distinct hydraulic properties, in the fen. Layer 2 is 1.5 m thick, and extends from 1.0 to 2.5 m below the ground surface. The layer spacing was systematically increased and the deepest model layer, 7, has a thickness of 8.3 m. There are 101,389 active grid cells in the model. Given the presence of relatively thin layers near the land surface, some model cells are in the unsaturated zone during flow simulations. In certain areas, the water table drops below the base of a model layer during the summer dry season and may subsequently rise into the layer during periods of higher recharge.