PUBLICATIONS--Release of two new reports documenting computer programs WGS-Mail Stop 411 December 5, 1989 OFFICE OF GROUND WATER TECHNICAL MEMORANDUM NO. 90.02 Subject: PUBLICATIONS--Release of two new reports documenting computer programs The two subject reports are: Leake, S.A., and Prudic, D.E., 1988, Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 88-482, 80 p. Prudic, David E., 1989, Documentation of a computer program to simulate stream-aquifer relations using a modular, finite- difference, ground-water flow model: U.S. Geological Survey Open-File Report 88-729, 113 p. The report by Leake and Prudic (1988) documents a new program, the Interbed-Storage Package, that simulates changes in ground-water storage caused by compressible interbeds in an aquifer system. This package has been incorporated into the modular computer program of McDonald and Harbaugh (1988, TWRI, Book 6, Chapter A1). In addition to accounting for changes in storage, the package also calculates permanent (inelastic) compaction as well as recoverable (elastic) compaction of sediments. The report also describes the Time-Variant Specified Head Package which was developed to allow constant head nodes to take on different values for each time step. The authors have sent copies of the report to each District Office, Regional Ground-Water Specialist, and RASA project chief. Additional copies of the report are available from Stan Leake (WRD, Tucson, Arizona). The report by Prudic (1989) documents a new program, the Streamflow-Routing Package, that can be used to simulate interaction between surface streams and ground water. This package is not a true surface-water flow model but rather is an accounting program that tracks the flow in one or more streams in addition to computing leakage between the streams and the aquifer system. The stage in each reach can be computed using the Manning formula. This package has been incorporated into the modular computer program of McDonald and Harbaugh (1988, TWRI, Book 6, Chapter A1). A copy of this report is attached and is being distributed to District, State, Regional, and some subdistrict offices of the Division. Water Resources Division employees may obtain the computer programs described in these reports from the Software Exchange System (SOFTEX) on the QVARSA Prime computer. The SOFTEX entry for the Interbed-Storage Package is AZSAL 00003. The SOFTEX entry for the Streamflow-Routing Package is NVSAW00001. We recommend that this information be brought to the attention of technical and management personnel concerned with ground-water studies. Eugene P. Patten Chief, Office of Ground Water Attachment WRD Distribution: A & B (memo only), S, FO, & PO (memo w/attachment).