User's guide of Proceessing Modflow 5.0

254 Processing Modflow
no recharge was allowed for the following 180 days. The distribution of the recharge over time
is shown in Fig. 6.27.
Fig. 6.26 Configuration of the model and the location of the observation well
Modeling Approach and Simulation Results
The aquifer is simulated using one model layer. Specification of the elevations of layer top and
bottom are not necessary, because the layer is confined and transmissivity and confined storage
coefficient are specified directly (as defined in the Layer Options dialog box). The sinusoidal
distribution of the recharge rate was divided into 15-day intervals for the model simulation and
the rate for the middle of each interval was used as a constant. The distribution used in the
simulation is also shown in Fig. 6.27. A total of six 360-day infiltration periods (144 stress
periods, each with a length of 15 days) were used in the simulation. The first five 360-day
infiltration periods were computed to allow the model to reach a stable yearly cycle because the
starting water level for each model cell was not known. Results of the model simulation from
the sixth infiltration period are compared to the results from the analytical solution for an
observation well 2,000 ft from the river (Fig. 6.28). The coordinates of the observation well is
given in the Boreholes and Observations dialog box. The Streamflow-Routing package is not
really needed to simulate this condition, as the river could have been represented using fixed-
6.2.6 Simulation of an Aquifer System with irregular Recharge and a Stream