User's guide of Proceessing Modflow 5.0

Processing Modflow 233
Effective Porosity
The effective porosity is used in PMPATH, which we will use later to define the capture zone
of the pumping wells.
< To specify the effective porosity
1. Select Parameters < Effective Porosity
2. Use Value < Reset Matrix... to enter the following data for each layer
Layer 1 0.2
Layer 2 0.25
Layer 3 0.25
3. Leave the Data Editor by File < Leave Editor < Yes
River
The River data is a little difficult to set up. MODFLOW requires that the river stage (ie. head),
river bottom elevation and riverbed conductance be specified. The riverbed conductance is
defined as:
CRIV '
where,
K @ L @ W
M
2
CRIV = hydraulic conductance of the riverbed [L /T]
K = hydraulic conductivity of the riverbed sediment [L/T]
L = length of the river within a cell [L]
W = width of the river within a cell [L]
M = thickness of the riverbed [L]
In our case the riverbed has the following properties:
K = 2 m/day
L = 250 or 125 m depending on the length of the river with the cell
W = 100 m
M = 1 m
< To specify the river data
1. Select Models < MODFLOW < River
2. You will notice that the river meanders across the model domain and rarely is contained
within a single cell. First, you need to decide the river data for each cell using the equation
6.1.2 Tutorial 2 - Confined and Unconfined Aquifer System with River