DRAINMOD is a computer model that was developed by Dr. R. W. Skaggs, Professor, North Carolina State University, Raleigh, North Carolina to simulate the performance of water table management systems.  DRAINMOD was first used as a research tool to investigate the performance of drainage and subirrigation systems and their effects on water use, crop response, land treatment of wastewater, and pollutant movement from agricultural fields (see for example, Skaggs, 1978; Ravelo et al., 1982; Massey et al., 1983; Skaggs and NassehzadehTabrizi, 1985 and Deal et al., 1986).  Some applications of the model for actual design of  drainage and subirrigation systems were made in  North Carolina in the late 1970's.

The foundation for application on a wide scale was laid in 1979 when, under the leadership of Walter J. Ochs, the USDA-SCS accepted the modeling concept and supported development of the "DRAINMOD REFERENCE REPORT"; "Methods for Design and Evaluation of Drainage-Water Management Systems for Soils with High Water Tables" (Skaggs, 1980).  DRAINMOD was installed on the USDA computer in Washington, D.C. where it was accessible from state SCS offices throughout the United States.  P. Lucas and R. Wenberg, SCS Regional  Drainage Engineers in the Midwest and South regions, respectively, had leadership rolls in developing the SCS DRAINMOD User's Manual and in conducting training sessions for the application of the model.

Dr. B. H. Nolte of The Ohio State University and a group of Cooperative State Extension Service, University, and USDA agricultural engineers in the midwest contributed to the development and application of the model via a project sponsored by the North Central Computer Institute (NCCI).  The objective of the project was to provide DRAINMOD design documentation for application in the North Central Region.  As part of the project a PC version  of the model was written.  By the end of the NCCI project in 1985, FORTRAN compilers were available for the PC and both the YIELD and standard versions of DRAINMOD were made available in FORTRAN on the PC.  The NCCI project resulted in a design document (Nolte et al., 1986) and an improved user's manual.  These documents, together with both BASIC and FORTRAN PC versions of the model were distributed, by NCCI, The Ohio State University, and North Carolina State University.

Since 1985, several PC versions of DRAINMOD have evolved with improvements to make the program more flexible and easier to use.  Input requirements and format did not differ significantly from the original mainframe versions, so those versions were distributed with the old user's manuals.

Version 4.0 incorporated several improvements developed in the water management program at N. C. State University.  It involved restructuring the program to better organize input information and to make the program easier to use.  Help screens have been developed and are easily accessible by the user.  The "YIELD" component, which was formerly in a separate version of the model has been incorporated into DRAINMOD.  The model is no longer restricted to application on slopes less than 5 percent and has the capability to simulate lateral and deep seepage from the field.  Daily potential evapotranspiration data may be directly input to the model if these data are available.  The ability to input data for several simulations and execute them in batch mode has been included in this latest version of the model.  Programming of version 4.0 was done primarily by Dr. J. E. Parsons and K. D. Konyha.  K. D. Robbins was primarily responsible for rewriting the weather data section of the model.

Version 4.6 incorporated  several more improvements to DRAINMOD.   Routines were added to facilitate analyses of wetland hydrologic criteria. Routines were also added to allow use of monthly PET values, and water management strategies that combine subirrigation and controlled drainage.  The new version was also modified to output rankings of monthly rainfall, ET, drainage rates, and average water table depths. .  Programming of version 4.6 was done primarily by Dr. J. E. Parsons and Dr. D. M. Amatya.