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Dept. of Biological and Agricultural Engineering 
DrainMod

A Computer Simulation Model

About

DRAINMOD is a computer simulation model developed by Dr. Wayne Skaggs at the Department of Biological & Agricultural Engineering, North Carolina State University, Raleigh, NC in 1980. The model simulates the hydrology of poorly drained, high water table soils on an hour-by-hour, day-by-day basis for long periods of climatological record (e.g. 50 years). The model predicts the effects of drainage and associated water management practices on water table depths, the soil water regime and crop yields. Parallel DitchesIt has been used to analyze the hydrology of certain types of wetlands and to determine whether the wetland hydrologic criterion is satisfied for drained or partially drained sites. The model is also used to determine the hydraulic capacity of systems for land treatment of wastewater. The model has been successfully tested and applied in wide variety of geographical and soils conditions. In the last 20 years, the model’s capability has been extended to predict the effects of drainage and water management practices on the hydrology and water quality of agricultural and forested lands both on field and watershed scale.

The latest version, DRAINMOD 6.0 , combines the original DRAINMOD hydrology model with DRAINMOD-N (nitrogen sub-model) and DRAINMOD-S (salinity sub-model) into a Windows based program. The new version includes a graphical user interface that allows easy preparation of input data sets, running simulations as well as displaying model outputs. In addition to organizing the hydrology, nitrogen, and salinity components of DRAINMOD, the interface facilitates analyses of the effect of drainage system design on subsurface drainage, surface runoff, SEW30, crop yield, and nitrogen loss in surface and subsurface drainage by automatically editing drainage design parameters (e.g. drain spacing & drain depth) over a specified range, simulating the different designs and graphically displaying the results. The interface also calculates the runoff volume from surrounding areas that drain to a site and adds that runoff volume to a DRAINMOD water balance of the site. Version 6.0 also includes routines for soil temperature modeling and considers freezing and thawing effects on drainage processes.

Mission

To develop methods to manage poorly drained soils for the production of food and fiber while maintaining environmental quality.

Goals

  • Development of methods for managing water, fertilizers and pesticides to minimize losses of pollutants to the environment while maintaining or enhancing agricultural productivity.
  • Development of simulation models for describing effects of alternative design and management decisions on water quality and crop yields.
  • Develop methods for describing the hydrology and water quality of drained forested wetlands, and for restoring these functions to degraded wetlands.
  • Conduct experimental studies and develop models to describe in-stream processes controlling the transport and fate of pollutants, and to link them with field scale models so that cumulative impacts of land uses and management practices can be addressed on a watershed scale.