River Package (RIV1)

Please Register

Last modified on Wednesday, January 31, 1996 - 6:52:01 PM

Skip forward to Input instructions for the River Package.

The original instructions for the River Package (RIV1) are on pages 6-14 to 6-15 of McDonald and Harbaugh (1988).

Introduction: The River Package is used to simulate groundwater flow to or from a river. If you wish the model to determine when the river, or parts of it, dry out during the simulation or you wish to track the volume of flow in the river, you need to use the Streamflow-Routing Package. There is a separate program which links MODFLOW to a 1-dimensional stream model. The Drain Package is similar to the River package, however, the aquifer is not recharged from drains.

Both this package and the Streamflow-Routing and Drain packages can be coded in ways that make no physical sense. For example, river reaches can be discontinuous and may not be in the uppermost active layer and in the Streamflow-Routing package, streams can flow uphill. It is up to the user to ensure that the model input is meaningful.

When the head in the aquifer is lower than the elevation of the base of the riverbed material, recharge of the aquifer by the river is assumed to be constant. At all higher heads, there is a linear relationship between head and groundwater flow. The shift from recharge of the aquifer to discharge to the river occurs at the point where the head in the aquifer equals the head in the river.

Go back to Contents

Input instructions

• Line 1
  • Spaces 1-10, MXRIVR, Integer, Maximum number of river reaches active at one time
  • Spaces 11-20, IRIVCB, Integer, (You must also set ICBCFL in the Output Control option to print or save cell-by-cell flow terms.)
    • if IRIVCB > 0, IRIVCB is the unit number for cell-by-cell flow terms;
    • if IRIVCB = 0, cell-by-cell flow terms will not be printed or saved;
    • if IRIVCB< 0, River leakage will be printed on the main output file.
• Lines 2+, One copy of Lines 2+ followed by 0 or ITMP copies of Lines 3+ are read for each stress period.
  • Spaces 1-10, ITMP, Integer
    • If < 0, river data from the last stress period will be reused
    • If >= 0, ITMP is the number of active reaches during the current stress period.
• Lines 3+, The number of copies of Lines 3+ depends on ITMP in Lines 2+
  • Spaces 1-10, Layer, Integer, The layer number of the cell containing the river reach
  • Spaces 11-20, Row, Integer, The row number of the cell containing the the river reach
  • Spaces 21-30, Column, Integer, The column number of the cell containing the river reach
  • Spaces 31-40, Stage, the head in the river
  • Spaces 41-50, Cond, riverbed hydraulic conductance
  • Spaces 51-60, Rbot, the elevation of the bottom of the river bed.

Line 1, Spaces 1-10, Variable = MXRIVR, Integer

Go back to Input instructions for the River Package

Line 1, Spaces 11-20, Variable = IRIVCB, Integer

• if IRIVCB > 0, unit number for cell-by-cell flow terms;
• if IRIVCB = 0, cell-by-cell flow terms will not be printed or saved;
• if IRIVCB < 0, River leakage will be printed in the main output file.

Lines 2+, Spaces 1-10, Variable = ITMP, Integer

• If ITMP < 0, river data from the last stress period will be used. There will be 0 copies of Lines 3+ immediately following this copy of Line 2.
• If ITMP >= 0, ITMP is the number of active reaches during the current stress period. There will be ITMP copies of Lines 3+ immediately following this copy of Line 2.

Go back to Input instructions for the River Package

Lines 3+, Spaces 1-10, Variable = Layer, Integer

Go back to Input instructions for the River Package

Lines 3+, Spaces 11-20, Variable = Row, Integer

Go back to Input instructions for the River Package

Lines 3+, Spaces 21-30, Variable = Column, Integer

Go back to Input instructions for the River Package

Lines 3+, Spaces 31-40, Variable = Stage

Go back to Input instructions for the River Package

Lines 3+, Spaces 41-50, Variable = Cond

• K = the hydraulic conductivity of the riverbed material,
• L = the length of the reach,
• W = the width of the River, and
• M = the thickness of the riverbed material.

Go back to Input instructions for the River Package

Lines 3+, Spaces 51-60, Variable = Rbot

Go back to Input instructions for the River Package
Go back to Contents