User's guide of Proceessing Modflow 5.0

Processing Modflow 241
6.2.2 Use of the General-Head Boundary Condition
Folder: \pm5\examples\basic\basic2\
Overview of the Problem
This simple example demonstrates the use of the general-head boundary package of
MODFLOW. A confined, homogeneous and isotropic aquifer is shown in Fig. 6.18. The aquifer
is bounded by a no-flow zones to the north and south. The hydraulic heads at the west and east
2
boundaries are 12m and 10m, respectively. The transmissivity of the aquifer is T = 0.01 m /s.
The aquifer has a constant thickness of 10 m.
Your task is to calculate the head contours for the case that only the west part of the aquifer
is modelled. The east boundary of the modelled part should be approached by using the general-
head boundary.
Fig. 6.18 Plan view of the model area
Modeling Approach and simulation results
The aquifer is simulated using a grid containing 1 layer, 10 rows and 16 columns. A regualar
grid space of 100 m is used for each column and row. The layer type is 0: cofined and the
Transmissity flag in the Layer Options dialog box is User-specified. The initial hydraulic
head is 12 m everywhere. While the west model boundary is simulated by the fixed-head
boundary condition (IBOUND=-1) with the initial head at 12 m, the east boundary is simulated
by the general-head boundary (GHB) condition with the head h = 10 m. Analogous to the
6.2.2 Use of the General-Head Boundary Condition