GROUND WATER -- Release of Open-File Report 91-536, A Method of Converting No-Flow Cells to Variable-Head Cells In Reply Refer To: February 21, 1992 Mail Stop 411 OFFICE OF GROUND WATER TECHNICAL MEMORANDUM NO. 92.04 Subject: GROUND WATER -- Release of Open-File Report 91-536, "A Method of Converting No-Flow Cells to Variable-Head Cells for the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model," by M.G. McDonald, A.W. Harbaugh, B.R. Orr, and D.J. Ackerman The subject report describes an addition to the U.S. Geological Survey modular model, MODFLOW, which allows dry (no flow) model cells to convert to wet (variable head). This new capability will be useful for simulating a rising water table that crosses into previously dry cells. Typical examples are the recovery of water levels after pumping has stopped and rising water levels caused by artificial recharge. The report describes how to add the new capability to MODFLOW and how to use it. The program code can be retrieved from the QVARSA Prime computer. Two files are in directory MODFLOW: BCF2.F77 -- source code for the new MODFLOW package BCF2.CALL -- Call statements for the Main MODFLOW program To retrieve these files, issue the following commands from any of our Prime computers: FTR MODFLOW>BCF2.F77 FTS_DEPOT>== -SS QVARSA FTR MODFLOW>BCF2.CALL FTS_DEPOT>== -SS QVARSA We recommend that this report be brought to the attention of technical and management personnel concerned with ground-water modeling studies. Additional copies of the report are available from the Office of Ground Water. Joseph S. Rosenshein Acting Chief, Office of Ground Water Distribution: A and B (memo only) S, FO, and PO (memo and report)