zonebudget(1) U.S. Geological Survey (wrdapp) zonebudget(1) NAME zonebudget - Program for computing subregional water budgets for MODFLOW ground-water flow models ABSTRACT Zonebudget (ZONBUD) is a computer program that computes subregional water budgets using results from the MODFLOW ground- water flow model. The user designates the subregions by specifying zone numbers. A separate budget is computed for each zone. The budget for a zone includes a component of flow between each adjacent zone. METHOD ZONBUD reads a file of budget data that MODFLOW can write. This file must contain values for each flow component at every model cell. ZONBUD then accumulates each flow component for all the cells in each specified zone. HISTORY Version 3.01 12/18/2009 -- updated to fix a problem in the csv2 output file when a simulation has both transient and steady-state stress periods. In this situation, the STORAGE column label was absent if the first stress period is steady state; however, the storage values were written for the transient time steps. The updated code always includes a storage column label, and the storage value is 0 for the steady-state time steps. Also reduced the time needed to determine that a budget file is double precision. Version 3.0 9/19/2008 -- updated to automatically read single precision and double precision cell-by-cell budget files. The ability to write data into a comma-delimited file for use by a spreadsheet program was added also. The input for the zone file has been updated to allow free format. Version 2.1 2000/04/18 - updated to allow specifiers for opening unformatted files to be easily modified. The personal computer version of the code is being distributed using unstructured unformatted files. Version 2.0 2000/04/24 - updated to read compact budget files that MODFLOW-96 and MODFLOW-2000 can optionally write. Compact budget files use less disk space. They also include additional information that allows multiple budget values of the same type at the same cell (for eample, river seepage) to be differentiated. In such situations, ZONBUD did not tabulate the budget in the same manner as MODFLOW (see USGS OFR 90-392, p. 3). By using the Compact budget files and version 2.0 of ZONBUD, the budget will always be tabulated in the same manner by MODFLOW and ZONBUD. Note further that when the CHTOCH option is used in MODFLOW-2000, which is used when simulating contaminant transport, then ZONBUD will produce incorrect results in some situations unless the COMPACT budget option is used. (The incorrect results can occur if there is flow between adjacent constant-head cells.) For the above reasons, it is recommended that the MODFLOW Compact budget option be used whenever ZONBUD will be used to analyze the budget file. This assures correct and consistent results, and minimizes the amount of disk space. Version 1.0 1996/12/20 - version published in USGS OFR 90-392. Note that this version will not work with cell-by-cell budget files that are written using the optional compact format available in MODFLOW-96. That is, to use ZONBUD version 1.0 with MODFLOW-96, the compact cell-by-cell budget option must NOT be used. DATA REQUIREMENTS In order to use ZONBUD, all cell-by-cell budget terms for a MODFLOW simulation must be saved in a file when MODFLOW is executed. As described above in the HISTORY section, it is best to save the cell-by-cell budget data using the COMPACT format, which is an option that was added to MODFLOW-96 and further enhanced in MODFLOW-2000. Depending on the specific zones that are desired, a zone file must also be prepared. OUTPUT OPTIONS The output is a listing file that contains a flow budget for each zone. SYSTEM REQUIREMENTS ZONBUD is written in Fortran 90. Generally, the program is easily installed on most computer systems. The code has been used on UNIX-based and Microsoft Windows based computers. DOCUMENTATION Harbaugh, A.W., 1990, A computer program for calculating subregional water budgets using results from the U.S. Geological Survey modular three-dimensional ground-water flow model: U.S. Geological Survey Open-File Report 90-392, 46 p. Documentation about changes to the version 3 code changes are contained in file zonbud3.pdf, which is distributed with the Zonebudget Version 3 code. RELATED DOCUMENTATION Harbaugh, A.W., 2005, MODFLOW-2005, the U.S. Geological Survey modular ground-water model -- the Ground-Water Flow Process: U.S. Geological Survey Techniques and Methods 6-A16, variously p. McDonald, M.G., and Harbaugh, A.W., 1988, A modular three- dimensional finite-difference ground-water flow model: U.S. Geological Survey Techniques of Water-Resources Investigations, book 6, chap. A1, 586 p. Harbaugh, A.W., and McDonald, M.G., 1996, User's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 96-485, 56 p. Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 1996, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- user guide to modularization concepts and the ground-water flow process: U.S. Geological Survey Open-File Report 00-92. CONTACTS Operation: U.S. Geological Survey Office of Ground Water Arlen Harbaugh 411 National Center Reston, VA 20192 harbaugh@usgs.gov